Charge : 0.01BTC
Service: Will calculate how much BTC should be deposited into the ponzi to get back your payout accurately.
Fee will be taken into account. Balance on the wallet will be taken into account. It will be calculated directly from your deposit (including it.)
Usefulness: For risk assessment. This is subjective and I will not provide any opinion. Just the math part.
Disclaimer: Experimental service.
Disclosure: I have nothing to do with all these ponzis.
Don't the ponzi sites already offer this telling how much is required for the next payout ?
"The next payout" meaning the next person in line to be paid. OP will calculate how much is required for you to deposit, as in you're just about to get in that line to be paid.