Tools
Casino Bonus Calculator
Enter any bonus details to instantly calculate its real expected value, break-even probability, and effective return on your deposit.
Cash credited, not match %. 100% on £100 = £100 bonus.
Smaller bets = lower variance per session.
Most casinos count slots at 100% toward wagering. Blackjack/roulette often count at 10% or are excluded - check T&Cs and adjust the contribution field below.
e.g. 10% if blackjack counts at 10x multiplied wagering.
UKGC casinos: deposit always withdrawable.
Many bonuses cap winnings - check the T&Cs. Leaving blank assumes no cap.
Monte Carlo Simulation 50,000 sessions
Calculating...
Simulates 50,000 sessions using CLT with per-game variance. Results vary slightly each run. Enter a max cashout for the most accurate picture - uncapped high-volatility bonuses have very wide upside.
Advantage play tip
If your goal is clearing wagering and withdrawing - not entertainment - set game volume to 0 and switch your screen to greyscale (iOS: Settings > Accessibility > Display & Text Size > Colour Filters; Android: Developer Options > Simulate colour space). Sounds and colours are engineered to trigger engagement. Remove them and treat it as a maths problem.
Why bet size matters
Bet size directly controls variance. A £1 bet through £3,500 wagering = 3,500 spins. A £10 bet = 350 spins. More spins means outcomes cluster tighter around the EV. Fewer spins means wild swings - higher chance of both a big profit and a big loss.
Bonus type explained
Bonus only (UKGC standard): Your deposit sits in a separate wallet and is always withdrawable. Only the bonus balance is at risk. Worst case: the bonus runs to zero, you withdraw your deposit and walk away flat.
Deposit + Bonus locked: Both must clear wagering before anything is withdrawable. Your deposit can be lost. More common offshore. EV is substantially worse - avoid if possible.
High volatility vs low volatility
Blackjack and high-vol slots can have identical EV for a given bonus. But high-vol slots give a higher probability of profiting because the wide distribution shifts more sessions into positive territory. The trade-off is the downside is also wider. For a -EV bonus, high variance maximises your profit probability - at the cost of busting more often.
Game contribution %
Many casinos only count slots at 100% toward wagering. Blackjack might count at 10%, meaning you need to wager 10x more to clear the requirement. Enter the actual contribution rate from your T&Cs - it dramatically changes the true EV calculation.