RTP Calculator: What Slot Returns Actually Cost You
This calculator shows you the expected cost of playing a slot at any given RTP over any number of spins. Enter your stake per spin, the number of spins, and the deployed RTP at your casino. The calculator returns your expected loss — the amount the house edge will cost you on average over that many spins.
The key word is "expected." Individual sessions will vary due to volatility. But over hundreds or thousands of spins, actual results converge toward these numbers. Use this to compare the cost of playing the same game at different casinos — if one deploys Book of Dead at 96.21% and another at 87.25%, this calculator shows you exactly what that gap costs in pounds.
How much you wager on each spin
Return to Player percentage — check your slot's in-game info screen
How many spins you plan to play
Expected Loss
£20.00
Total Wagered
£500.00
Total amount wagered over the session
Expected Return
£480.00
Average amount returned (statistical expectation)
House Edge
4.00%
The casino's mathematical margin on each spin
RTP Comparison at £500.00 Wagered
| RTP | House Edge | Expected Loss | Extra Cost vs Your RTP |
|---|---|---|---|
| 99.00% | 1.00% | £5.00 | -£15.00 |
| 97.00% | 3.00% | £15.00 | -£5.00 |
| 96.00% | 4.00% | £20.00 | Your RTP |
| 95.00% | 5.00% | £25.00 | +£5.00 |
| 94.00% | 6.00% | £30.00 | +£10.00 |
| 92.00% | 8.00% | £40.00 | +£20.00 |
| 90.00% | 10.00% | £50.00 | +£30.00 |
RTP does not guarantee wins. Return to Player percentages reflect long-term mathematical averages across millions of spins. Individual sessions can and will produce results that differ significantly from theoretical RTP. Slot outcomes are determined by certified random number generators. Play responsibly.
These calculations use mathematical expectation. Your actual results will vary — volatility means individual sessions can be better or worse than the expected value. The expected loss represents the average outcome across thousands of identical scenarios. It is the most reliable predictor of long-term cost available to players.
How This Calculator Works
The RTP calculator uses the standard mathematical definition of Return to Player. Over sufficient wagering volume, a slot returns a percentage of total wagers to players equal to the RTP. The remaining percentage is the house edge — the casino's mathematical margin. Expected loss is calculated as total wagered multiplied by the house edge percentage. Expected return is total wagered multiplied by the RTP percentage. These expectations apply to the long-term mathematical average — individual sessions vary due to variance.
What the Numbers Actually Mean
The expected loss figure shown is the statistical average of what you would lose if you played this stake and spin count on this RTP configuration across thousands of similar sessions. Any individual session can produce outcomes ranging from zero loss (session with big wins) to total loss of session budget (cold variance session). The expected loss is the central tendency, not the specific outcome.
For short sessions (500 spins or fewer), actual outcomes often deviate substantially from expected values due to variance. The RTP calculation becomes more reliable as a predictor of outcomes over very large spin volumes — typically tens of thousands of spins.
Why RTP Differences Matter
A 2 percentage point RTP difference (96% vs 94%) doubles the house edge (4% vs 6%). Over £500 wagered, the 2pp RTP reduction increases expected loss by £10 — from £20 to £30. Over £10,000 wagered (achievable over several years of moderate play), the same 2pp difference increases expected loss by £200.
Over long-term play, RTP differences compound into substantial money. The calculator's comparison table shows how a single session's expected cost varies across RTP levels. Extending these differences over years of play produces the cumulative impact RTP-conscious players use to guide casino and slot selection.
UK 2026 Context
The April 2026 UK Remote Gaming Duty increase from 21% to 40% drove many UKGC-licensed casinos to deploy slots at reduced RTP tiers. A slot you previously played at 96% at a UK casino may now run at 94% or lower at that same casino without notification. Use the calculator to quantify the cost impact of these reductions on your personal wagering patterns — the cumulative effect is often larger than players expect.