Which one is ok? Or what would you say?
If I tell you, it's not a surprise.
If I tell you, it won't be a surprise.ant this;
If I tell you, It'll ruin the surprise.

Question

Which one is ok?  Or what would you say?
If I tell you, it's not a surprise.
If I tell you, it won't be a surprise.ant this;
If I tell you, It'll ruin the surprise.

Answer

Yes, those are good.

Answer

The second and third are best but the first one would be understood even if it's not perfect.

Answer

They're all fine.

Answer

The third one sounds the most casual. They all seem correct though. But the first one sounds a little bit funny. You can also say, "If I tell you, I'll ruin the surprise".