How do i measure?

Im having a spot of trouble trying to figure this out. I have 7" pots, potting soil and perlite, i was told to mix 70% soil with 30% perlite, how do i work this out so i have the right amount of each?

Thanks.

use a pint glass to mix it up and do it in 10s.... so 7 pints soil 3 pints perlite

thats how I would do it if i were mixing it

Cheers, ill give that a go.

I just use a small dixie cup. Just use the same size thing and get 7 scoops of whatever and three of whatever and mix it up good..