Tha Khantho (Thai: ท่าคันโท, pronounced [tʰâː kʰān.tʰōː]) is the northwesternmost district (amphoe) of Kalasin province, northeastern Thailand.
Neighboring districts are (from the south clockwise): Nong Kung Si of Kalasin Province; Kranuan of Khon Kaen province; Kumphawapi, Si That, and Wang Sam Mo of Udon Thani province.
The minor district (king amphoe) Tha Khantho was established on 1 October 1962, when the two tambons Tha Khantho and Khok Khruea were split off from Sahatsakhan district.
Khok Khruea was later reassigned to Nong Kung Si District.
The district is divided into six sub-districts (tambons), which are further subdivided into 59 villages (mubans).