1. Off the top of my head
Example : Off the top of my head, this phone would be worth £300.
2. Knowing him, he will……
Example : Knowing Bryan, he will probably take the train, he hates driving.
3. If I had to take a guess, I’d say……
Example : If I had to take a guess, I’d say he was over 40 years old.
4. It’s difficult to say, but I think……
Example : It’s difficult to say, but I think anyone can won this match now.
5. I wouldn’t be surprised if……
Example : I wouldn’t be surprised if he leaves his job, he is too stressed for the kind of work he does.
6. I bet……
Example : I bet he’s gonna ask me out tonight, he just can’t stop staring.
7. It’s somewhere in the ballpark of……
Example : She gets paid somewhere in the ballpark of 10 million dollars to host that show.
8. Your guess is as good as mine.
Example : When someone says to you ..”Don’t even know if Mary will show up for the wedding..” and you have no idea , you just say..”well, Your guess is as good as mine”