Estimate concrete for round driveway 

I think I almost understand it, at last! Thank you very much for the video. I appreciate how much work goes into a “simple” pour!

For the mathematically challenged, just get a large roll of string. Lay out the string all around the future concrete perimeter making sure you are dead on (or slightly outside - but definitely not inside the future concrete area). When done, gather up the string and measure its length. Divide the string length by 4 to effectively turn the "curved" or "any random area" into a simple "square". Multiply side one (1/4 the string) by side 2 (1/4 the string) to get "area" of the "square". Multiply that number by the concrete thickness (example: .33 for 4 inch slab or .5 for 6 inch slab or ?/12 for any other depth) and divide that number by 27 (3 ft x 3 ft x 3 ft = 27 for a cubic yard) to get the cubic yards of concrete needed. To check this method out, lets say the string measures 12 foot and you're pouring a 3 foot (OMG) slab. 12/4 = 3. ; 3*3=9 ; 9*3=27 ; 27/27=1 ; 1 Cubic Yard of concrete would be needed.

your videos help so much is there any way you can to a video showing us how to do it in lineal feet i would like to learn

I think I need to study chemistry and algebra to do my driveway.

Is the 20' the radius of just the Inner Circle? or is that the Center of the entire circle?