How to calculate how much concrete I need??

Hi

I'm working on a project and I'm up to the concreting but I don't know how much to buy. I know how to calculate the volume of a square but this one's a really odd shape (a sort of weird circular shape) & I don't know how to work it out. Any ideas??

I usually use an app (I use it on Android, not sure about other systems like iPhones) which helps make it easy to calc the volume of shapes for concrete
https://play.google.com/store/apps/deta ... ult#?t=W10.

If you don't use a smartphone maybe you can find something similar online to help?

approximation!!!! Try to make other shapes out of it. Maybe an over dimensioned triangle.

Don't try to be too exact. You'll end up running short. If it's a concave arc just calculate the areas you can and then halve that arced area. Then add 10-20% to the total