とも

とも after a number and counter means "all" or "both": every one of that many, with none left out. りょうほうとも両方とも and どちらとも work the same way.

With a negative verb, the whole group is negated: "neither", "none of".

It goes with a small number you could count off. A vague amount cannot take it; use みんな or ぜんぶ全部 instead: ×たくさんとも.

"Even if", "no matter"

After a volitional verb, or an い-adjective in its く-form, とも means "even if". It is written and formal; the everyday form is ても.

The verb takes the volitional form, not the dictionary form: ×たとえ失敗するとも, but たとえ失敗しようとも. A noun or な-adjective takes であろうとも.

だれ誰, なん何 or どこ with the volitional give "no matter who / what / where": だれ誰がはんたい反対しようとも. 誰とも on its own is a different thing, と plus も: だれ誰ともはなしたくない話したくない, "I don't want to talk to anyone".

Usage notes

These go beyond counting and "even if".

Sentence-final とも

At the end of a sentence, after a plain form, とも means "of course", "certainly". It sounds old-fashioned or hearty.

Set phrases

すくなく少なくとも, "at least", and おそく遅くとも, "at the latest", are the く-form plus とも fixed as adverbs.