The headline on a bonus is a pound figure. The offer is the six or seven lines underneath it, and those lines interact — a multiple that looks reasonable becomes punishing once game weighting is applied, and a maximum bet clause quietly decides whether any winnings survive at all. This tool takes the terms as written and produces the two numbers that matter: what the playthrough is expected to cost, and whether the stake you intend to use is permitted.
Nothing is sent anywhere. Read the numbers off the promotion's terms and type them in.
The arithmetic, so you can check it
wagering to clear = base amount × multiple
money staked = wagering to clear ÷ game contribution
expected loss = money staked × (1 − RTP)
rough value = bonus − expected loss
Work the default by hand. A £25 bonus at 40× applied to the bonus alone requires £1,000 of wagering. On a game contributing 100%, that is £1,000 actually staked. At 96% RTP the house edge is 4%, so £1,000 of turnover is expected to cost £40. The bonus is £25. The playthrough is expected to cost £15 more than the bonus is worth, and takes about 2,000 spins at 50p.
Switch the basis to deposit plus bonus and the base becomes £50, the wagering £2,000, the expected cost £80 against the same £25. One line of terms, three times the bill.
Why "expected loss" is the right unit
People compare bonuses by multiple — 30× versus 40× — which is comparing turnover requirements without pricing them. Turnover is not free. It is charged at the house edge, so the same 40× costs half as much on a 98% game as on a 92% one, and the multiple alone cannot tell you that.
There is a break-even point and it is easy to find. Ignoring contribution weighting, a bonus-only requirement is worth taking on average when:
multiple × (1 − RTP) is less than 1
At 96% RTP that puts the threshold at a multiple of 25. At 94% it falls to about 16.7. At 92%, to 12.5. Most published requirements sit well above those lines, which is not a scandal so much as a pricing decision: an offer that came out positive for the average player would not be offered.
That does not make bonuses worthless. It makes them a discount on play you were going to do anyway rather than a source of income. If the bonus is the reason you are staking £1,000, it has cost you money to obtain.
Game contribution does more damage than the multiple
Contribution is the percentage of each pound staked that counts toward the requirement, and it varies by game category. Slots commonly count in full. Table games, video poker and live dealer games frequently count at a small fraction or not at all.
| Contribution | £1,000 requirement means staking | Expected cost at 96% RTP |
|---|---|---|
| 100% | £1,000 | £40 |
| 50% | £2,000 | £80 |
| 20% | £5,000 | £200 |
| 10% | £10,000 | £400 |
The pattern is not accidental. The games excluded or heavily discounted from wagering are, as a rule, the low-house-edge ones — which is to say the games where the operator would recover least from the turnover it is requiring. Contribution is the mechanism that stops a bonus being cleared cheaply.
Six terms, and the order they bite in
| Term | What to look for | Why it moves the answer |
|---|---|---|
| Wagering multiple | Usually 20× to 50× | Sets the turnover directly |
| Applied to | Bonus only, or deposit + bonus | Doubles turnover on a 100% match |
| Game contribution | Slots often 100%; tables far less | A 10% weighting means ten times the staking |
| Max bet while active | Frequently a few pounds a spin | Breaching it is the usual grounds for voiding |
| Maximum conversion | A cap on what can be withdrawn | Removes the upside, not the downside |
| Expiry | Often days rather than weeks | Forces a pace, which forces volume |
The calculator deliberately ignores maximum conversion, which means the figure it gives you is the optimistic one. A cap that limits withdrawals from bonus play to a few multiples of the bonus does not reduce your expected loss by a penny — the edge is charged on every spin regardless — but it deletes the rare large outcome that was propping the average up. The terms that void winnings goes through the clauses in the order they tend to cause trouble.
18+. No bonus alters the house edge and no wagering requirement gets cheaper by playing longer. Free, confidential support is available from the National Gambling Helpline on 0808 8020 133.