Dic/ Usages/ I'll say, I would say

I'll say.

  - I agree. (based on the full form 'I will say the same thing')

  - Absolutely. I strongly agree. (Synonym: you can say that again.)

• "Did you enjoy the film?" "I'll Say."

I'll say! used to show that you agree very strongly with what has been said.

• "Does he eat a lot?" "I'll say!" 

'I would say' and 'I guess' have the same meaning?

 - I would say he is not coming.
 - I guess he is not coming.

A participant says:

They have only very approximately the same meaning, in that both imply some degree of uncertainty and leave room for others or for facts-on-the-ground to contradict what follows.

• I would say characterizes what follows as a personal opinion or judgment: ex) From what I know of him I would say he is coming.
• I guess characterizes what follows as a conjecture or inference: ex) Well, if he were coming he'd be here by now, so I guess he's not coming.

But there's obviously room for some overlap: an opinion may be based on inference, and a conjecture may be based on opinion.

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