Casino bonus math: what wagering really costs (with 100,000 simulations)
A 100% bonus with 35x wagering sounds like free money. The math says otherwise. Formulas, simulations, charts and a calculator you can run yourself.
The short answer
Every wagering requirement can be turned into two numbers:
- How much you must bet: wagering × the amount it applies to.
- What that costs on average: the amount you must bet × the house edge (1 − RTP).
Take a common offer: deposit $100, get a 100% bonus ($100), 35x wagering on the bonus. You must bet $3,500 before you can withdraw. On a slot with 96% RTP, the house keeps 4% of everything you bet on average, so those bets cost about $140. The bonus gives you $100. On average, you are $40 worse off than if you had taken no bonus.
Bonus is worth it on average if bonus > required bets × (1 − RTP)
For wagering on the bonus only, the break-even point is 1 ÷ (1 − RTP): 25x at 96% RTP, 33x at 97%, 20x at 95%.
What 50,000 players per offer would see
Averages hide what actually happens to one person. So we simulated it: for each wagering level from 0x to 60x, we played the same $100 + $100 offer 50,000 times on a slot with 96% RTP and $1 spins, stopping when the wagering was done (withdraw everything) or the money ran out.
- Low volatility
- Medium volatility
- High volatility
- Simple formula (no bust)
Average result = what you withdraw minus your $100 deposit. Above $0 the bonus made money on average.
Up to about 10x, the bonus is clearly worth it: on medium volatility, the average player ends $60 up and 99.8% finish the wagering. Around 25x it breaks even, as the formula predicts. At 35x the average is −$26, and only 64.1% of sessions get to withdraw anything.
- Low volatility
- Medium volatility
- High volatility
Why volatile slots look better on average, and usually aren't
The dashed line in the first chart is the simple formula. At high wagering the simulated averages sit above it, most of all for high-volatility games. That's because you can't lose more than your balance: once it hits zero, you stop paying the house edge.
Volatile games use this most. At 40x, a high-volatility slot averages $2, while a low-volatility one averages −$49. But look at the typical player: the median result on the high-volatility slot is −$100. Most sessions lose everything; a few big wins carry the average. Only 35.6% finish the wagering.
| Wagering | You must bet | Finish wagering | End in profit | Average | Median |
|---|---|---|---|---|---|
| 0x | $0 | 100% | 100% | $100 | $100 |
| 1x | $100 | 100% | 100% | $96 | $96 |
| 5x | $500 | 100% | 98.5% | $80 | $80 |
| 10x | $1,000 | 99.8% | 87.4% | $60 | $60 |
| 15x | $1,500 | 97.5% | 73.2% | $40 | $40 |
| 20x | $2,000 | 92.2% | 60.6% | $21 | $20 |
| 25x | $2,500 | 83.4% | 49.5% | $3 | −$1 |
| 30x | $3,000 | 73.9% | 40.9% | −$12 | −$21 |
| 35x | $3,500 | 64.1% | 34.1% | −$26 | −$42 |
| 40x | $4,000 | 55% | 28.2% | −$38 | −$68 |
| 50x | $5,000 | 39.1% | 19.4% | −$56 | −$100 |
| 60x | $6,000 | 27.5% | 13.3% | −$70 | −$100 |
The “bonus + deposit” trap
Some casinos apply wagering to the bonus and your deposit. With a 100% bonus, that doubles the bets you need. The same 35x goes from $3,500 to $7,000, the share of players who finish drops from 64.1% to 19.3%, and the average result falls from −$26 to −$79.
This is the part most people miss. In a 2023 UK experiment with 4,012 adults who gamble, the Behavioural Insights Team found that 7 in 10 could not work out how much they needed to bet, rising to almost 9 in 10 when wagering applied to bonus + deposit. Most underestimated it.
Max cashout: the cap on your upside
Many bonuses cap what you can withdraw, for example 5x your deposit. That cap only bites on big wins, so it hurts most where big wins carry the average: on high volatility at 35x, a 5x cap lowers the average from $10 to $6. On medium volatility it barely matters (−$25 with or without it), because few sessions reach $500.
Game weighting and other fine print
- Game weighting: slots usually count 100%, table games often 10–20% or nothing. At 10% weighting, every $1 on blackjack counts as $0.10, so the bets you need grow tenfold.
- Max bet while wagering: often $5 or 10% of the bonus. Breaking it can void winnings.
- Time limits: 7 to 30 days is common. Unfinished wagering is usually forfeited.
- Sticky vs non-sticky: with a non-sticky bonus you play your own money first and can withdraw it before the bonus kicks in. It's usually the better deal.
What regulators decided
In Great Britain, the Gambling Commission capped wagering on bonuses at 10x from 19 January 2026, saying it lowers the risk of harm and makes offers easier to understand. Before that, some operators used requirements of up to 60x. The Behavioural Insights Team's experiment fed into that decision; it recommended going further, to 1x on the bonus only, and banning “bonus + deposit” wagering.
Crypto casinos licensed elsewhere, such as Curaçao or Anjouan, aren't bound by the UK cap, which is why 30x to 60x offers are still common. Use the calculator below before you opt in.
Run your own numbers
Enter the offer you're looking at. The calculator plays it 100,000 times in your browser.
You must bet $3,500 before you can withdraw. At 96.0% RTP, that costs about $140 on average, against a $100 bonus. Above 25.0x this bonus loses money on average.
Before you take a bonus
- Work out the bets you need: wagering × bonus (or × bonus + deposit).
- Multiply by the house edge of the games you'll play. If that's more than the bonus, skip it.
- Check max cashout, max bet, game weighting and the time limit.
- Prefer non-sticky bonuses and low wagering. A small bonus at 5x beats a big one at 40x.
- Never deposit more to “unlock” a bonus than you'd happily spend on entertainment.
How we simulated it
Each spin wins with a fixed chance (45% low, 25% medium, 5% high volatility) and pays enough to give the stated RTP; otherwise it loses the stake. To run 100,000 sessions quickly, spins are grouped into blocks whose total follows a normal distribution. The session ends when the wagering is met (you withdraw the balance, capped if a max cashout applies) or when the balance can't cover a spin. Real slots have more complex pay tables, bonus rounds and jackpots, so treat the figures as a guide to the shape of the risk, not a forecast. Study data generated on 2026-10-31 with a fixed random seed.
Questions
How do I calculate a wagering requirement?
Multiply the wagering number by the amount it applies to. A $100 bonus with 35x wagering on the bonus means $3,500 in bets. If it applies to bonus + deposit, a $100 deposit and $100 bonus need $7,000.
At what wagering does a bonus stop being worth it?
On average, a bonus loses value when the expected cost of the required bets is larger than the bonus. For wagering on the bonus only, that point is 1 ÷ (1 − RTP): 25x at 96% RTP, 33x at 97%, 20x at 95%.
Does game volatility change the result?
Yes. Volatile games make you more likely to lose the whole balance before you finish wagering, but the few sessions that hit a big win pull the average up. The typical player still loses more often.
Sources
- Behavioural Insights Team (April 2024), Should wagering requirements on gambling bonus offers be capped? Results deck. Online randomised trial, 4,012 UK adults, December 2023.
- Gambling Commission (26 March 2025, updated 24 July 2025), Gambling promotions to be safer and simpler.
- Gambling Commission, LCCP Social Responsibility Code 5.1.1.
Related: Wagering requirements explained · 9 signs a casino won't pay · Responsible gambling