- Maths reviewed by Josh Miller
- Tested by Diana Westfield
£10 rolled over five times at evens turns into £320. That’s the screenshot that gets shared. The CasinoCalcs compound betting calculator above shows the rest: at a realistic 48% win rate, all five win about 2.5% of the time, and the expected value of the whole chain is £8.15. It’s a free calculator built to show what compounding does to your bank, not to sell you a plan.
Compound betting calculator: the rollover
A rollover is just an accumulator placed one bet at a time. The maths is the same:
| Steps at evens | If all win | Chance (48% each) | Expected value of £10 |
|---|---|---|---|
| 3 | £80 | 11.1% (1 in 9) | £8.85 |
| 5 | £320 | 2.5% (1 in 39) | £8.15 |
| 10 | £10,240 | 0.065% (1 in 1,540) | £6.65 |
Every step at 48% knocks 4% off the expected value. Ten steps lose a third of it. The prize grows, but the price of the dream grows faster.
Percentage staking: the slower version
The other kind of compounding stakes a set share of the bank, say 5%, so stakes grow when you win. Switch the calculator to this mode and it shows two numbers. The average bank after 100 evens bets at 48% is £818 from £1,000. The typical bank is lower, £722, because a few lucky runs pull the average up. Most punters end up nearer the median.
With a real edge, percentage staking is the sensible way to grow a bank, and the Kelly criterion calculator finds the best stake size. Without one, it just loses more slowly than a rollover.
Find your real win rate first
Everything here depends on the win rate box. At evens you need more than 50% to break even, and with the bookmaker’s margin most people sit below it. If you’ve kept records, the betting ROI calculator and the luck vs skill calculator tell you whether your edge is real before you compound it.
Chasing a big number with a rollover is how small stakes turn into big losses. BeGambleAware.org is free and confidential if it stops being fun.