Where do I find how much social security tax I owe for my deferred payments? (self-employed)

I am self-employed and I selected that I want to defer some of my social security taxes and pay half of that amount at the end of this year and the other half next year. When I filled it out, it showed me how much I will owe but now that I filed my tax return, I can't find it anywhere. How do I find out how much I owe? Thanks!