| nmnTaa | nmn | Khoisan | | 4,200 | 6b · Threatened |
| mkyTababahasa Taba | mky | Austronesian | | 20,000 | 6b · Threatened |
| tbyTabarubahasa Tabaru | tby | West Papuan | | 15,000 | 5 · Developing |
| tabTabasaran | tab | Northeast Caucasian | | 75,079 | 5 · Developing |
| nhcTabasco Nahuatl | nhc | Uto-Aztecan | | | 8b · Nearly Extinct |
| tnmTablabahasa Jakari | tnm | Sentani | | | 8a · Moribund |
| tzxTabriak | tzx | Ramu–Lower Sepik | | | 6a · Vigorous |
| tapTabwa | tap | Niger–Congo | | 382,000 | 5 · Developing |
| xttTacahua Mixtec | xtt | Central American Indian languages | | | 6b · Threatened |
| tnaTacana | tna | Pano-Tacanan | | 1,800 | 7 · Shifting |
| dsqTadaksahak | dsq | Nilo-Saharan | | 100,000 | 6a · Vigorous |
| tdyTadyawan | tdy | Austronesian | | | 6a · Vigorous |
| robTae’bahasa Tae' | rob | Austronesian | | | 5 · Developing |
| tcdTafi | tcd | Niger–Congo | | | 6a · Vigorous |
| bgsTagabawa | bgs | — | | 43,000 | 4 · Educational |
| klgTagakaulo | klg | — | | | 4 · Educational |
| mvvTagal Murutbahasa Tagal Murut | mvv | Austronesian | | | 6b · Threatened |
| tgzTagalaka | tgz | Australian Aboriginal languages | | | 10 · Extinct |
| tglTagalogwikang Tagalog | tgl | Austronesian | | 68.6 m | 3 · Wider Communication |
| tbmTagbo | tbm | Niger–Congo | | | 6a · Vigorous |
| tgjTagin | tgj | Sino-Tibetan | | | 6a · Vigorous |
| tgxTagish | tgx | Na-Dene | | | 9 · Dormant |
| tagTagoi | tag | Niger–Congo | | | 6b · Threatened |
| tgwTagwana | tgw | Niger–Congo | | | 6a · Vigorous |
| tahTahitianreo tahiti | tah | Austronesian | | 68,000 | 1 · National |
| thtTahltan | tht | Na-Dene | | | 8a · Moribund |
| ttqTahouaⵜⴰⵎⴰⵌⵈ | ttq | Afroasiatic | | 640,000 | 6a · Vigorous |
| tawTai | taw | Trans–New Guinea | | | 5 · Developing |
| tyrTai Daeng | tyr | Kra–Dai | | 650,000 | 6a · Vigorous |
| bltTai Dam | blt | Kra–Dai | +1 | 760,000 | 5 · Developing |
| tyjTai Do | tyj | Kra–Dai | | | 6b · Threatened |
| twhTai Dón | twh | — | | 280,000 | 6a · Vigorous |
| tnuTai Khang | tnu | Kra–Dai | | | 6b · Threatened |
| tjlTai Laing | tjl | Kra–Dai | | 100,000 | 6b · Threatened |
| tlqTai Loi | tlq | Austroasiatic | | | 6a · Vigorous |
| khbTai Lü | khb | Kra–Dai | | 700,000 | 2 · Provincial |
| tmpTai Mène | tmp | Kra–Dai | | | |
| tddTai Nüa | tdd | Kra–Dai | +1 | 650,000 | 4 · Educational |
| tpoTai Pao | tpo | Kra–Dai | | | 6b · Threatened |
| phkTai Phake | phk | Kra–Dai | | | 4 · Educational |
| gpnTaiap | gpn | — | | | 8a · Moribund |
| aosTaikatbahasa Arso | aos | Border | | | 6b · Threatened |
| tnqTaíno | tnq | Ta-Arawakan | +1 | | 9 · Dormant |
| davTaita | dav | Niger–Congo | | | 5 · Developing |
| tvxTaivoan | tvx | Austronesian | | | 9 · Dormant |
| tssTaiwanese Sign Language台灣手語 | tss | — | | | 6b · Threatened |
| acqTaʽizzi-Adeni Arabic | acq | Afroasiatic | | 10.5 m | 6a · Vigorous |
| peeTajebahasa Petapa | pee | Austronesian | | | 8b · Nearly Extinct |
| tgkTajikзабони тоҷикӣ | tgk | — | +2 | 14 m | 1 · National |
| abhTajiki Arabic | abh | Afroasiatic | | | 6b · Threatened |
| tdjTajiobahasa Adijo | tdj | Austronesian | | | 7 · Shifting |
| tksTakestani | tks | Indo-European | | | 7 · Shifting |
| tbcTakia | tbc | Austronesian | | | 5 · Developing |
| nhoTakuu | nho | Austronesian | | | 5 · Developing |
| takTala | tak | Afroasiatic | | 1,000 | 6b · Threatened |
| tlvTaliabubahasa Taliabo | tlv | Austronesian | | 1,500 | 6a · Vigorous |
| tljTalinga | tlj | Niger–Congo | | | 5 · Developing |
| tlrTalise | tlr | Austronesian | | | 6a · Vigorous |
| tloTalodi | tlo | Niger–Congo | | | 8b · Nearly Extinct |
| tlkTalokibahasa Taloki | tlk | Austronesian | | | 7 · Shifting |
| tlnTalondo’bahasa Talondo’ | tln | Austronesian | | | 6a · Vigorous |
| tzlTalossan | tzl | — | | | |
| ytaTalu | yta | Sino-Tibetan | | | Vulnerable |
| tlyTalyshTolyšə zyvon | tly | Indo-European | | 764,400 | 4 · Educational |
| tenTama | ten | Tucanoan | | | 10 · Extinct |
| tmaTama | tma | — | | | 6a · Vigorous |
| tcgTamagario | tcg | — | | | 6a · Vigorous |
| thvTamahaq | thv | Afroasiatic | | 112,900 | 6b · Threatened |
| mlaTamambo | mla | Austronesian | | | 5 · Developing |
| tclTaman | tcl | Sino-Tibetan | | | 9 · Dormant |
| tmnTaman | tmn | — | | | 6a · Vigorous |
| tmzTamanaku | tmz | — | | | 10 · Extinct |
| taqTamasheqⵜⵎⴰⵂⵈ | taq | Afroasiatic | +1 | 500,000 | 5 · Developing |
| tdkTambas | tdk | Afroasiatic | | | 6b · Threatened |
| xxtTambora | xxt | West Papuan | | | |
| tlsTambotalo | tls | Austronesian | | | 6b · Threatened |
| tmyTami | tmy | Austronesian | | | 5 · Developing |
| tamTamilதமிழ் | tam | Dravidian | +5 | 83 m | 2 · Provincial |
| taxTamki | tax | Afroasiatic | | | 6b · Threatened |
| tbzTammari | tbz | Niger–Congo | | | 5 · Developing |
| lowTampias Lobu | low | Austronesian | | | 6b · Threatened |
| tpuTampuan | tpu | Austroasiatic | | | 6a · Vigorous |
| tcbTanacross | tcb | Na-Dene | | | 8a · Moribund |
| tpvTanapagTalaabwogh | tpv | Austronesian | | 10 | 7 · Shifting |
| tnvTanchangya | tnv | Indo-European | | | 6a · Vigorous |
| ygmTandɨ | ygm | Trans–New Guinea | | | 6b · Threatened |
| tgnTandaganon | tgn | Austronesian | | | 6a · Vigorous |
| tniTandia | tni | Austronesian | | | 9 · Dormant |
| tdxTandroy | tdx | Austronesian | | | 6a · Vigorous |
| tnxTanema | tnx | Austronesian | | 4 | 8b · Nearly Extinct |
| tanTangale | tan | Afroasiatic | | 130,000 | 6b · Threatened |
| tguTanggu | tgu | Ramu–Lower Sepik | | | 5 · Developing |
| nmfTangkhul | nmf | — | | | 4 · Educational |
| tkxTangko | tkx | Trans–New Guinea | | | 6b · Threatened |
| tgpTangoa | tgp | Austronesian | | | 5 · Developing |
| nstTangsa | nst | Sino-Tibetan | | | 5 · Developing |
| tbsTanguat | tbs | Ramu–Lower Sepik | | | 6a · Vigorous |
| txgTangut𗼇𗟲 | txg | Sino-Tibetan | | | |
| tbeTanimbili | tbe | Austronesian | | | 8b · Nearly Extinct |
| tncTanimuca-Retuarã | tnc | Tucanoan | | 300 | 6b · Threatened |
| txyTanosy Malagasy | txy | Austronesian | | | 6a · Vigorous |
| kmlTanudan Kalinga | kml | Austronesian | | | 5 · Developing |
| tzaTanzanian Sign Language | tza | — | | 278,000 | 5 · Developing |
| afpTapei | afp | Arafundi | | | 6a · Vigorous |
| tpjTapieté | tpj | Tupian | | | 6b · Threatened |
| tafTapirapé | taf | Tupian | | | 6a · Vigorous |
| kcmTar Gula | kcm | Nilo-Saharan | | | 6a · Vigorous |
| troTarao | tro | Sino-Tibetan | | | 6a · Vigorous |
| wneTareeno | wne | Indo-European | | | 6a · Vigorous |
| taeTariana | tae | Upper Amazon Arawakan | | 100 | 8a · Moribund |
| rifTarifit | rif | Afroasiatic | | 4.4 m | 5 · Developing |
| txjTarjumo | txj | Nilo-Saharan | | | 9 · Second language only |
| yerTarok | yer | Niger–Congo | | | 5 · Developing |
| tpfTarpia | tpf | Austronesian | | | 8a · Moribund |
| tdmTaruma | tdm | — | | | 8b · Nearly Extinct |
| trtTarunggare | trt | — | | | 6b · Threatened |
| twqTasawaq | twq | Nilo-Saharan | | | 6a · Vigorous |
| shiTashelhitTaclḥit | shi | Afroasiatic | | 8 m | 5 · Developing |
| xtzTasmanian | xtz | Australian Aboriginal languages | | | |
| tmtTasmate | tmt | Austronesian | | | 6b · Threatened |
| tttTat | ttt | Indo-European | +1 | | 6b · Threatened |
| ctaTataltepec Chatino | cta | Central American Indian languages | | | 6b · Threatened |
| tatTatarтатар теле | tat | Turkic | | 5.4 m | 2 · Provincial |
| tavTatuyo | tav | Tucanoan | | 400 | 6a · Vigorous |
| ttdTauade | ttd | Binanderean–Goilalan | | | 5 · Developing |
| tuhTaulil | tuh | — | | | 6a · Vigorous |
| tpaTaupota | tpa | Austronesian | | | 6a · Vigorous |
| tadTausebahasa Darha | tad | Lakes Plain | | | 6a · Vigorous |
| trrTaushiro | trr | — | | 1 | 8b · Nearly Extinct |
| tsgTausugbahasa Sūg | tsg | Austronesian | | 1.1 m | 3 · Wider Communication |
| tvsTaveta | tvs | Niger–Congo | | | 5 · Developing |
| tvnTavoyan | tvn | Sino-Tibetan | | | 6a · Vigorous |
| rmuTavringer Romani | rmu | Indo-European | | | 9 · Dormant |
| xtwTawandê | xtw | Nambikwaran | | | 8b · Nearly Extinct |
| twmTawang Monpa | twm | Bodish | | | 6a · Vigorous |
| twlTawara | twl | Niger–Congo | | | 6a · Vigorous |
| tbpTawortabahasa Bok | tbp | Lakes Plain | | 140 | 6b · Threatened |
| twyTawoyanbahasa Taboyan | twy | Austronesian | | | 5 · Developing |
| tyzTày | tyz | Kra–Dai | | 1.5 m | 6b · Threatened |
| tytTày Tac | tyt | — | | | 6a · Vigorous |
| cksTayo | cks | French-based creole languages | | | 7 · Shifting |
| grrTaznatit | grr | Afroasiatic | | | 6b · Threatened |
| tblTboli | tbl | Austronesian | | 95,000 | 4 · Educational |
| tckTchitchege | tck | Niger–Congo | | | 7 · Shifting |
| bqaTchumbuli | bqa | Niger–Congo | | | 8b · Nearly Extinct |
| tveTe'unbahasa Te’un | tve | Austronesian | | | 10 · Extinct |
| tkwTeanu | tkw | Austronesian | | 800 | 7 · Shifting |
| dmuTebi | dmu | Pauwasi | | | 8a · Moribund |
| dtuTebul Dogon | dtu | Niger–Congo | | | 6a · Vigorous |
| tsyTebul Sign Language | tsy | — | | 500 | 6a · Vigorous |
| maaTecóatl Mazatec | maa | — | | 18,900 | 6a · Vigorous |
| tcwTecpatlán Totonac | tcw | Totonacan | | | 6b · Threatened |
| tuqTeda | tuq | Nilo-Saharan | +1 | 42,500 | 6a · Vigorous |
| tkqTee | tkq | Niger–Congo | | | 6a · Vigorous |
| tfoTefarobahasa Demba | tfo | Geelvink Bay | | | 6b · Threatened |
| rasTegali | ras | Niger–Congo | | | 6b · Threatened |
| kpsTehit | kps | West Papuan | | | 6b · Threatened |
| tehTehuelche | teh | Chonan | | | 9 · Dormant |
| zttTejalapan Zapotec | ztt | Central American Indian languages | | | 8a · Moribund |
| nzuTeke-Nzikou | nzu | Niger–Congo | | | 6b · Threatened |
| tyxTeke-Tyee | tyx | Niger–Congo | | | 6a · Vigorous |
| ttcTektitek | ttc | Central American Indian languages | | | 6b · Threatened |
| tvmTela’a | tvm | Austronesian | | | 6a · Vigorous |
| tlfTelefol | tlf | Trans–New Guinea | | | 5 · Developing |
| telTeluguతెలుగు | tel | Dravidian | | 50 m | 2 · Provincial |
| tltTeluti | tlt | Austronesian | | | 6a · Vigorous |
| kdhTem | kdh | Niger–Congo | | | 3 · Wider Communication |
| nhvTemascaltepec Nahuatl | nhv | Uto-Aztecan | | 310 | 7 · Shifting |
| tqbTembé | tqb | Tupian | | | 8a · Moribund |
| tmvTembo | tmv | Niger–Congo | | | 6a · Vigorous |
| tbtTembo (Kitembo) | tbt | Niger–Congo | | | 5 · Developing |
| teqTemein | teq | Nilo-Saharan | | | 6b · Threatened |
| teaTemiar | tea | Austroasiatic | | | 3 · Wider Communication |
| temTemneKʌThemnɛ | tem | Niger–Congo | | | 2 · Provincial |
| tmoTemoq | tmo | Austroasiatic | | | 8b · Nearly Extinct |
| tmwTemuan | tmw | Austronesian | | 28,000 | 6b · Threatened |
| tnzTen'edn | tnz | Austroasiatic | | | 6a · Vigorous |
| vktTenggarong | vkt | Austronesian | | | 6a · Vigorous |
| tesTengger | tes | Austronesian | | | 6a · Vigorous |
| pahTenharim | pah | Tupian | | | 6b · Threatened |
| tqnTenino | tqn | Plateau Penutian | | | 8a · Moribund |
| tnsTenis | tns | Austronesian | | | 8b · Nearly Extinct |
| texTennet | tex | Nilo-Saharan | | | 5 · Developing |
| tioTeop | tio | Austronesian | | | 5 · Developing |
| tevTeor | tev | Austronesian | | | 6b · Threatened |
| tepTepecano | tep | Uto-Aztecan | | | 10 · Extinct |
| cuxTepeuxila Cuicatec | cux | Central American Indian languages | | | 6a · Vigorous |
| ashTequiraca | ash | — | | | 10 · Extinct |
| sjtTer Samisām’e kīll | sjt | Uralic | | 2 | 8b · Nearly Extinct |
| ttrTera | ttr | Afroasiatic | | | 6a · Vigorous |
| trbTerebu | trb | Austronesian | | | 6b · Threatened |
| terTerêna | ter | — | | 16,000 | 7 · Shifting |
| tefTeressa | tef | Austroasiatic | | | 6b · Threatened |
| twgTerewengbahasa Tereweng | twg | Trans–New Guinea | | | 6b · Threatened |
| tfrTeribe | tfr | Chibchan | | 3,000 | 5 · Developing |
| tecTerik | tec | Nilo-Saharan | | | 6a · Vigorous |
| twuTermanubahasa Termanu | twu | Austronesian | | | 6a · Vigorous |
| tftTernatebahasa Ternate | tft | West Papuan | | 42,000 | 6b · Threatened |
| tmgTernateñobahasa Ternateño | tmg | — | | | 10 · Extinct |
| tkgTesaka Malagasy | tkg | Austronesian | | | 6a · Vigorous |
| kegTese | keg | — | | | 6b · Threatened |
| teoTeso | teo | Nilo-Saharan | | | 5 · Developing |
| tllTetela | tll | Niger–Congo | | | 6a · Vigorous |
| nhgTetelcingo Nahuatl | nhg | Uto-Aztecan | | 3,500 | 6b · Threatened |
| tebTeteté | teb | Tucanoan | | | 10 · Extinct |
| tezTetserret | tez | Afroasiatic | | 2,000 | 6b · Threatened |
| tetTetumLia-tetun | tet | Austronesian | +1 | 463,500 | 5 · Developing |
| tdtTetun Dili | tdt | Austronesian | | | 1 · National |
| cutTeutila Cuicatec | cut | Central American Indian languages | | | 6b · Threatened |
| tweTewabahasa Tewa | twe | — | | | 6a · Vigorous |
| tewTewa | tew | Tanoan | | | 6b · Threatened |
| twxTewe | twx | Niger–Congo | | | 6a · Vigorous |
| poqTexistepec Popoluca | poq | Mixe–Zoque | | | 8b · Nearly Extinct |
| mxbTezoatlán Mixtec | mxb | Central American Indian languages | | | 5 · Developing |
| thyTha | thy | Niger–Congo | | | 6b · Threatened |
| thnThachanadan | thn | Dravidian | | | 6b · Threatened |
| tczThadou | tcz | Sino-Tibetan | | | 4 · Educational |
| thaThaiภาษาไทย | tha | Kra–Dai | +1 | 60.7 m | 1 · National |
| tsqThai Sign Language | tsq | — | | | 5 · Developing |
| soaThai Song | soa | Kra–Dai | | | 6b · Threatened |
| thsThakali | ths | Bodish | | | 6b · Threatened |
| thfThangmi | thf | Sino-Tibetan | | | 6b · Threatened |
| ssfThao | ssf | Austronesian | | | 9 · Dormant |
| thkTharaka | thk | Niger–Congo | | 176,000 | 5 · Developing |
| tbhTharawal | tbh | Australian Aboriginal languages | | | 9 · Dormant |
| thmThavung | thm | Austroasiatic | | | 6b · Threatened |
| xtvThawa | xtv | Australian Aboriginal languages | | | 10 · Extinct |
| tctThen | tct | Kra–Dai | | | 6b · Threatened |
| iinThiin | iin | Australian Aboriginal languages | | | 10 · Extinct |
| touTho | tou | Austroasiatic | | | 6a · Vigorous |
| ytlTholo | ytl | Sino-Tibetan | | | 6b · Threatened |
| thpThompson | thp | Salishan | | 440 | 8a · Moribund |
| txhThracian | txh | Indo-European | | | |
| tylThu Lao | tyl | Kra–Dai | | | 6b · Threatened |
| thwThudam | thw | — | | | 6a · Vigorous |
| tdhThulung | tdh | Sino-Tibetan | | | 5 · Developing |
| lthThur | lth | Nilo-Saharan | | | 5 · Developing |
| thuThuri | thu | — | | | 7 · Shifting |
| tbjTiang | tbj | Austronesian | | | 6a · Vigorous |
| ngyTibea | ngy | — | | | 6b · Threatened |
| bodTibetanབོད་ཡིག | bod | — | | 1.2 m | 2 · Provincial |
| lsnTibetan Sign Language | lsn | — | | 500 | 7 · Shifting |
| byjTiBin | byj | Niger–Congo | | | 6a · Vigorous |
| tcnTichurong | tcn | — | | | 6a · Vigorous |
| tcaTicunaDuüxügu | tca | — | | 61,000 | 5 · Developing |
| mtxTidaá Mixtec | mtx | Central American Indian languages | | | 6b · Threatened |
| tiaTidikelt | tia | Afroasiatic | | 1,000 | 8a · Moribund |
| tvoTidorebahasa Tidore | tvo | West Papuan | | | 6a · Vigorous |
| tidTidung | tid | Austronesian | | | |
| booTiemacewe Bozo | boo | Niger–Congo | | | 6a · Vigorous |
| tifTifal | tif | Trans–New Guinea | | | 5 · Developing |
| tgcTigak | tgc | Austronesian | | | 5 · Developing |
| nzaTigon | nza | Niger–Congo | | | 5 · Developing |
| tigTigreትግሬ | tig | Afroasiatic | | 800,000 | 4 · Educational |
| tirTigrinyaትግርኛ | tir | Afroasiatic | | 5.8 m | 2 · Provincial |
| txqTiibahasa Tii | txq | Austronesian | | | 6a · Vigorous |
| tikTikar | tik | Niger–Congo | | | 5 · Developing |
| tkpTikopia | tkp | Austronesian | | 3,324 | 5 · Developing |
| otlTilapa Otomi | otl | Central American Indian languages | | | 8a · Moribund |
| tilTillamook | til | Salishan | | | 10 · Extinct |
| tijTilung | tij | Sino-Tibetan | | | 7 · Shifting |
| tmsTima | tms | — | | | 8a · Moribund |
| parTimbisha | par | Uto-Aztecan | | | 8a · Moribund |
| tihTimugon | tih | — | | | 6b · Threatened |
| lbfTinani | lbf | Bodish | | | 6b · Threatened |
| tinTindi | tin | Northeast Caucasian | | 6,693 | 6b · Threatened |
| tieTingal | tie | Niger–Congo | | | Definitely endangered |
| titTinigua | tit | — | | 1 | 8b · Nearly Extinct |
| tpzTinputz | tpz | Austronesian | | | 5 · Developing |
| traTirahi | tra | — | | | 8b · Nearly Extinct |
| cirTîrî | cir | — | | | 7 · Shifting |
| triTiriyó | tri | Cariban | | 2,100 | 5 · Developing |
| tiyTiruray | tiy | — | | 50,000 | 5 · Developing |
| ttvTitan | ttv | Austronesian | | | 6a · Vigorous |
| tivTiv | tiv | Niger–Congo | | | 3 · Wider Communication |
| laxTiwa | lax | Sino-Tibetan | | | 6a · Vigorous |
| tiwTiwi | tiw | Australian Aboriginal languages | | 2,040 | 5 · Developing |
| tjpTjupany | tjp | Australian Aboriginal languages | | | 8b · Nearly Extinct |
| tptTlachichilco Tepehua | tpt | Totonacan | | | 6b · Threatened |
| tplTlacoapa Me'phaa | tpl | Central American Indian languages | | | 5 · Developing |
| ocuTlahuica | ocu | Central American Indian languages | | | 8a · Moribund |
| mxpTlahuitoltepec Mixe | mxp | Mixe–Zoque | | | 6a · Vigorous |
| tliTlingitLingít | tli | Na-Dene | | 500 | 8a · Moribund |
| tozTo | toz | Niger–Congo | | | 9 · Second language only |
| mluTo’abaita | mlu | Austronesian | | | 6a · Vigorous |
| tqoToaripi | tqo | — | | | 5 · Developing |
| bbcToba BatakHata Batak | bbc | Austronesian | | 2 m | 6b · Threatened |
| tobToba Qom | tob | Guaicuruan | | 40,000 | 6b · Threatened |
| ttiTobatibahasa Enggros | tti | Austronesian | | | 8b · Nearly Extinct |
| tlbTobelobahasa Tobelo | tlb | West Papuan | | 27,720 | 5 · Developing |
| toxTobianramari Hatohobei | tox | Austronesian | | | 6b · Threatened |
| tgbTobilung | tgb | Austronesian | | | 6b · Threatened |
| tbvTobo | tbv | Trans–New Guinea | | | 4 · Educational |
| asuTocantins Asurini | asu | Tupian | | | 7 · Shifting |
| xtoTocharian A | xto | Indo-European | | | |
| txbTocharian B | txb | Indo-European | | | |
| tazTocho | taz | Niger–Congo | | | 6b · Threatened |
| tkdTocodede | tkd | Austronesian | | | 6a · Vigorous |
| tcxToda | tcx | — | | | 6a · Vigorous |
| tdrTodrah | tdr | — | | 6,000 | 6a · Vigorous |
| kimTofaТоъфа дыл | kim | Turkic | | 93 | 8a · Moribund |
| tlgTofanma | tlg | — | | | 6a · Vigorous |
| tfiTofin | tfi | Niger–Congo | | | 6a · Vigorous |
| tgyTogoyo | tgy | Niger–Congo | | | 10 · Extinct |
| tojTojolab'al | toj | Central American Indian languages | | | 5 · Developing |
| tpiTok PisinTok pisin | tpi | — | | 4.1 m | 1 · National |
| zuhTokano | zuh | — | | | 5 · Developing |
| tklTokelauanTokelau | tkl | Austronesian | | 3,300 | 6b · Threatened |
| tknTokunoshima | tkn | Japonic | | | 7 · Shifting |
| jicTol | jic | Central American Indian languages | | 500 | 7 · Shifting |
| ksdTolai | ksd | Austronesian | | 81,000 | 3 · Wider Communication |
| lbwTolakibahasa Laki | lbw | Austronesian | | | 6b · Threatened |
| tlmTolomako | tlm | Austronesian | | | 6b · Threatened |
| tolTolowa | tol | Na-Dene | | | 9 · Reawakening |
| todToma | tod | Niger–Congo | | | 5 · Developing |
| tdiTomadinobahasa Tomadino | tdi | Austronesian | | | 8a · Moribund |
| tomTombulu | tom | Austronesian | | | 7 · Shifting |
| txmTomini | txm | Austronesian | | | 6b · Threatened |
| dtoTommo So Dogon | dto | Niger–Congo | | | 6a · Vigorous |
| tqpTomoip | tqp | Austronesian | | | 6a · Vigorous |
| tdnTondanobahasa Tolou | tdn | Austronesian | | | 7 · Shifting |
| toiTonga | toi | Niger–Congo | | 1.3 m | 2 · Provincial |
| togTonga | tog | Niger–Congo | | | 5 · Developing |
| tohTonga | toh | Niger–Congo | | | 5 · Developing |
| tonTonganLea fakatonga | ton | Austronesian | +5 | 186,010 | 1 · National |
| xgfTongva | xgf | Uto-Aztecan | | | |
| tnyTongwe | tny | Niger–Congo | | 31,600 | 6b · Threatened |
| tjnTonjon | tjn | Niger–Congo | | | 10 · Extinct |
| tqwTonkawa | tqw | — | | | 9 · Dormant |
| tnwTonsawangbahasa Tonsawang | tnw | Austronesian | | | 7 · Shifting |
| txsTonseabahasa Tonsea | txs | Austronesian | | | 6b · Threatened |
| tntTontemboan | tnt | Austronesian | | | 6b · Threatened |
| ttjTooro | ttj | Niger–Congo | | | 5 · Developing |
| toyTopoiyobahasa Topoiyo | toy | — | | | 8a · Moribund |
| toqToposa | toq | Nilo-Saharan | | | 5 · Developing |
| trzTorá | trz | Chapacuran | | | 9 · Dormant |
| sdaToraja-Sa’danbahasa Sa'dan | sda | Austronesian | | 500,000 | 5 · Developing |
| trjToram | trj | Afroasiatic | | | 8a · Moribund |
| ttuTorau | ttu | Austronesian | | | 6b · Threatened |
| tnoToromono | tno | Pano-Tacanan | | 200 | 9 · Dormant |
| tcsTorres Strait Creole | tcs | — | | 7,800 | 3 · Wider Communication |
| teiTorricelli | tei | Torricelli | | | 6a · Vigorous |
| trwTorwaliتوروالی | trw | — | | 90,000 | 6a · Vigorous |
| alsTosk AlbanianToskë | als | — | | 3 m | 1 · National |
| txoToto | txo | Sino-Tibetan | | | 6b · Threatened |
| txeTotolibahasa Gage | txe | Austronesian | | | 7 · Shifting |
| mtoTotontepec Mixe | mto | Mixe–Zoque | | 5,500 | 5 · Developing |
| ttkTotoro | ttk | Barbacoan | | | 9 · Dormant |
| tquTouo | tqu | — | | | 6a · Vigorous |
| donToura | don | Austronesian | | | 5 · Developing |
| ttnTowei | ttn | Pauwasi | | | 8a · Moribund |
| rmdTraveller Danish | rmd | Indo-European | | | 10 · Extinct |
| trmTregami | trm | Indo-European | | 1,000 | 6a · Vigorous |
| stgTrieng | stg | Austroasiatic | | | 6a · Vigorous |
| tipTrimuris | tip | Tor-Kwerba | | 300 | 6a · Vigorous |
| trxTringgus | trx | Austronesian | | | 6b · Threatened |
| trfTrinidadian Creole | trf | — | | | 6a · Vigorous |
| lstTrinidadian Sign Language | lst | — | | | 6a · Vigorous |
| tpyTrumaiho kod ke | tpy | — | | 120 | 8a · Moribund |
| tslTs'ün-Lao | tsl | Kra–Dai | | | 6a · Vigorous |
| cofTsachila | cof | Barbacoan | | 2,300 | 6b · Threatened |
| tkrTsakhurцӀаӀхна миз | tkr | Northeast Caucasian | | 23,000 | 6b · Threatened |
| tsdTsakonian | tsd | Indo-European | | 2,000 | 8a · Moribund |
| tsbTsamai | tsb | Afroasiatic | | | 5 · Developing |
| huqTsat | huq | Austronesian | | 3,800 | 6b · Threatened |
| kvzTsaukambobahasa Tsaukambo | kvz | — | | | 6b · Threatened |
| txcTsetsaut | txc | Na-Dene | | | Extinct |
| ddoTsez | ddo | Northeast Caucasian | | 12,467 | 6b · Threatened |
| tsjTshangla | tsj | Bodish | | 175,000 | 4 · Educational |
| hioTshwa | hio | Khoisan | | | 7 · Shifting |
| clcTsilhqotʹinTŝinlhqut’in | clc | Na-Dene | | 860 | 7 · Shifting |
| tsiTsimshian | tsi | Tsimshianic | | | 8a · Moribund |
| tswTsishingini | tsw | Niger–Congo | | | 5 · Developing |
| tsvTsogo | tsv | Niger–Congo | | | 6a · Vigorous |
| tsoTsonga | tso | Niger–Congo | +1 | 4 m | 1 · National |
| flyTsotsitaal | fly | — | | 500,000 | 9 · Second language only |
| tsuTsou | tsu | Austronesian | | 2,100 | 6b · Threatened |
| cbqTsucuba | cbq | Niger–Congo | | | 6b · Threatened |
| ttzTsum | ttz | — | | | 6a · Vigorous |
| srsTsuutʼina | srs | Na-Dene | | | 8a · Moribund |
| tshTsuvan | tsh | Afroasiatic | | | 6b · Threatened |
| tscTswa | tsc | Niger–Congo | | 1.2 m | 5 · Developing |
| tsnTswanaseTswana | tsn | Niger–Congo | +1 | 4.5 m | 1 · National |
| twoTswapong | two | Niger–Congo | | | 6a · Vigorous |
| pmtTuamotuan | pmt | Austronesian | | 15,000 | 6b · Threatened |
| tmhTuareg | tmh | Afroasiatic | +2 | 1.2 m | Vulnerable |
| tbuTubar | tbu | Uto-Aztecan | | | 10 · Extinct |
| tubTübatulabal | tub | Uto-Aztecan | | | 9 · Dormant |
| tuoTucanoDahseyé | tuo | Tucanoan | | | 5 · Developing |
| tuyTugen | tuy | Nilo-Saharan | | | 6a · Vigorous |
| tznTugun | tzn | Austronesian | | | 6a · Vigorous |
| tjoTugurt | tjo | Afroasiatic | | 8,100 | 7 · Shifting |
| tujTugutilbahasa Tugutil | tuj | West Papuan | | | 6b · Threatened |
| bagTuki | bag | Niger–Congo | | | 6a · Vigorous |
| tpqTukpa | tpq | — | | | 6b · Threatened |
| tulTula | tul | — | | 30,000 | 6a · Vigorous |
| tluTulehu | tlu | Austronesian | | | 7 · Shifting |
| teyTulishi | tey | Niger–Congo | | | 6b · Threatened |
| tcyTuluತುಳು | tcy | Dravidian | | 2 m | 5 · Developing |
| rakTulu-Bohuai | rak | Austronesian | | | 6a · Vigorous |