How much computer storage space needed for iPhone backup?

Trying to backup my iphone but it keeps stopping because there's not enough space. There was 18GB free space on computer. My iphone is a 64GB which was mostly used up. So do i need 64GB of space for my backup?

Yes you will need more than 64GB of space on the computer. FYI You really don't want to leave less than 10GB of space on any computer since it will start to function incorrectly or crash if you do that.

You need 65 gigs