How to check how much space is free in the current working directory?

How to check how much space is free in the current working directory on a Linux system?

I have a filesize file which contains 1073741824 which is the amount of disk space in bytes that is needed.

I need something to check in a script that in the folder are contents-of-filesize * 1,25 bytes free. How to do that?

pwd can print the path of the current folder, but how to combine that with df?