Slot Budget Calculator Decide What You'll Spend First, Then Pick the Stake to Match

How the recommended stake is worked out

The calculation is straightforward. Your session length and spin rate give the number of spins — 60 minutes at 10 spins a minute is 600 spins. The RTP gives the house edge: a 96% slot keeps 4% of everything staked. So the stake that spends exactly your budget over that session is budget ÷ (spins × house edge). For £50 over 600 spins at 4%, that's £50 ÷ 24 = £2.08, which the calculator rounds down to £2.00 so it lands on a stake you can actually set.

Rounding is always down, never to the nearest value, so the suggested stake never expects to spend more than the budget you entered. Below 50p it rounds to the nearest penny, below £2 to the nearest 5p, and above that to the nearest 10p.

What this figure does and doesn't promise

It is an average, and this is the part worth reading twice. A stake tuned so that the expected loss equals your budget means that, across many sessions, you'd spend roughly your budget each time. It does not mean your money will reliably last the full hour. In any single session it might vanish in twenty minutes, or you might finish ahead. Roughly half of real sessions will run out before the time is up, and on a high-volatility game considerably more than half.

That's volatility, and no budgeting formula can remove it. If your priority is genuinely playing for the full session rather than spending a set amount, use a smaller stake than the one suggested — halving it roughly doubles your cushion against a bad run. The calculator shows you that cushion figure directly in the note under the results.

To see the variance rather than just read about it, run the same numbers through our bankroll simulator. It plays out a session spin by spin and graphs the balance, so you can watch how differently two sessions on the identical stake and RTP can go. Setting it to high volatility is the quickest way to understand why the average is a poor guide to any individual evening.

Why the RTP input matters here

The house edge is the entire denominator of this calculation, so the RTP of the game you pick changes the answer more than anything else. At 96% you can stake £2.00 a spin on a £50 hour. Drop to a 94% build of the same game and the edge rises by half, so the same budget over the same hour supports only £1.35 a spin. Put the other way round: if you kept staking £2.00 on the 94% build, your £50 would be expected to last about 42 minutes rather than the full hour.

That's a real and avoidable cost, because the same slot is frequently offered at several different RTPs and the operator chooses which one to run. Check the slot database for the game you intend to play and find a casino running the higher build before you start. Our RTP calculator shows what a given percentage costs over any stake and spin count.