Risk of Ruin Calculation

[jkpickett]

I've been scouring the internet and this site for a way to calculate RoR in regards to betting sports. I keep find the poker calculators, but does anyone know where I can find one for sports? I want to be able to put in 1-3% units, total BR, different winrates, etc. to get a % RoR.
Also I know this site advocates a 1-2% unit, but how great does a 3% unit affect the RoR? My friend uses 3% units and has never been bust in 4 years, but I feel like I'm not near as skilled at picking games as I have lost every handicapping contest I've been in with him. Thanks guys.