Casino Bonus Calculator — Work Out Real Welcome Offer Value (2026)

↻ Last updated 18 April 2026 · Reviewed by our UK editorial team

Casino welcome bonuses look better than they often are. This calculator lets you enter a bonus offer’s key terms and work out your realistic expected value — the amount you’d expect to keep after wagering requirements, stake caps and eligibility restrictions. Use it before claiming any offer.

How to Use This Calculator

1. Find the offer you’re considering. On the operator’s promotions page or terms page, locate the deposit match percentage, free spins count, spin value and wagering requirement.
2. Enter your planned deposit amount. Enter what you realistically plan to deposit, not the maximum bonus cap.
3. Set the match percentage. For a "100% up to £100 match" enter 100; for "100 free spins on signup" without a match, enter 0.
4. Add free spins details. Enter the number of spins and the value per spin (usually printed in the T&Cs, typically 10p or 20p).
5. Enter the wagering requirement. Since January 2026, the UKGC caps this at 10x for UK operators — but always read the T&Cs.
6. Enter the RTP of the game. Slots vary from 88% to 99%. Rainbow Riches original is 95%. See our RTP page for franchise figures.
7. Read the Expected Keep. If it's higher than your deposit, the offer is positive EV on paper. If it's lower, the offer has negative expected value and you’re playing for entertainment.

What Affects Your Real Return

Wagering Requirement

The most important factor. A 10x requirement means you must wager your bonus (and sometimes your deposit) ten times before winnings are withdrawable. At 95% RTP slots, 10x wagering erodes about half the bonus’s value to house edge over the playthrough. Higher wagering requirements compound this rapidly — which is why the 2026 UKGC 10x cap is a significant player-protection measure.

Game Restrictions

Most UK operators only count slot play at 100% toward wagering. Live casino, table games and progressive jackpots often count at 10-25%, or not at all. If the offer requires you to play games that contribute less than 100%, your real wagering commitment is much higher than the headline number. Rainbow Riches generally contributes 100% to slot-based wagering at every UKGC-licensed casino.

Maximum Bet Caps

While a bonus is active, most operators cap per-spin stakes at £5 or less. Exceeding the cap voids the bonus and any winnings. This is usually invisible to casual players — if your normal stake is under £5, it doesn’t affect you.

Maximum Cashout from Bonus

Some offers cap the amount you can withdraw from bonus winnings — regardless of how much you win. A "100 free spins" offer with a £100 maximum cashout means any wins above £100 are forfeited. The calculator doesn’t account for this; read the T&Cs.

Time Limit

Bonuses expire, usually within 30 days. If you can’t complete the wagering within the window, the bonus and any associated winnings are removed. Shorter time windows (7 days, 14 days) materially harm expected value because they force accelerated play.

When Bonuses Are Actually Good Value

The genuinely good offers share common features:

• Wagering requirement at or below 10x (ideally 5x or lower)
• No maximum cashout cap on bonus winnings
• 30-day minimum completion window
• Eligible games include high-RTP slots (Rainbow Riches sequels are good for this)
• 100% slot contribution to wagering
• Reasonable minimum deposit (£10 typical)

Notably, PlayOJO’s zero-wagering welcome offer clears all these hurdles by having no wagering requirement at all. Wins from the welcome spins are paid as real cash, immediately withdrawable. This is why PlayOJO scores highly in our review methodology despite a lower headline offer value.

When Bonuses Are Worse Than They Look

Red flags:

• Wagering requirements above 10x (automatically disqualified under UK 2026 rules anyway)
• "Bonus and deposit" wagering structure (wager of both, not just bonus) — effectively doubles the hurdle
• Maximum cashout below the notional bonus value (e.g. £100 bonus capped at £50 withdrawal)
• Narrow game eligibility (only specific slots count)
• Under 14-day completion window
• Hidden stake caps (e.g. £1 maximum while bonus is active)

Limitations of This Calculator

This calculator gives a first-order mathematical estimate. It doesn’t account for:

• Variance — actual session outcomes vary enormously from the expected average
• Game contribution percentages (assumes 100% slot)
• Maximum cashout caps
• Minimum stake restrictions during bonus play
• Payment-method exclusions (e-wallet deposits often disqualified)
• Country / account-verification eligibility rules

For an honest assessment of any specific operator’s welcome offer, our individual reviews of the top 10 UK casinos include detailed wagering terms analysis.

Responsible Gambling

Positive expected value on paper does not mean you will win. Slots are designed to entertain with net losses on average — even bonus-adjusted EV is usually negative once real-world restrictions apply. Play only with money you can afford to lose, treat bonuses as entertainment subsidies rather than investment opportunities, and use UKGC-mandated deposit limits to stay in control. GamCare 0808 8020 133 for free confidential support.

18+ only. BeGambleAware.org. Full T&Cs apply. New players only. One bonus offer per player. Minimum deposit £10. Bonus spins on selected games only and must be used within 72 hours. Bonus funds must be used within 30 days otherwise any unused bonus shall be removed. Under UK Gambling Commission rules effective 19 January 2026, wagering requirements on casino bonuses are capped at 10x. Please gamble responsibly.