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Open the calculatorFREE · NO ACCOUNT · FREE TO EMBEDBankroll
Bankroll
Calculator.
Bankroll Calculator: How large does my bankroll need to be to survive a session of this length? Enter five figures and this page returns bankroll the session needs, with every line of the arithmetic printed rather than hidden. The worked example below answers 352.10 for the figures it states. Free to embed. Checked 2026-08-23.
Run it on your numbers352.10
01Run it on
Run it on
your numbers.
The fields open holding the worked example below, and the answer changes as you change them. Every line of the arithmetic is printed under the result, and the formula under that — so the answer can be checked rather than trusted.
Bankroll the session needs352.10The arithmetic,
The arithmetic,
line by line.
| Step | Value |
|---|---|
| Expected loss at 96.00% over 1,000 rounds | 40.00 |
| Swing buffer — z 1.6449 × SD 6.0 × √1,000 | 312.10 |
| Bankroll that lasts 95% of sessions | 352.10 |
| As a multiple of one round's stake | 352× |
expected loss = stake × rounds × (100 − RTP) ÷ 100 swing buffer = z × SD × stake × √rounds bankroll = expected loss + swing buffer
02The worked example,
The worked example,
in plain HTML.
| Input | Value | What it is |
|---|---|---|
| Stake per round | 1 | Any currency or coin. The bankroll comes back in the same unit. |
| Rounds in the session | 1000 | The single input people underestimate most. Autoplay reaches a thousand rounds in well under an hour. |
| Published RTP | 96% | Sets the expected loss the bankroll has to absorb before any swing is added. |
| Standard deviation per round | 6 | Your assumption, not our measurement. Studios publish volatility as a word rather than a number. Roughly: 1–2 for even-money table bets, 3–6 for low and medium slots, 10–20 for high-volatility slots and buy features. |
| Survive | 95% of sessions | How often the bankroll should be enough. It is never all of them: no finite bankroll survives every session. |
| Bankroll the session needs | 352.10 | Computed by the same function the calculator above runs. The build refuses to publish this page if the two disagree. |
A thousand rounds at 1 per round on a 96% game loses 40 on average, and the swing around that average is the part no folk rule contains: at an assumed standard deviation of 6 per round, ninety-five sessions in a hundred stay inside about 312 of it. The bankroll that survives the session is the two added together — around 352, or 352 times the stake that felt like the risk. Halve the volatility assumption and the buffer halves; quadruple the session length and it only doubles.
WHAT THIS CANNOT TELL YOUWhere the answer
Where the answer
stops being one.
Every calculator on this site ends here, because the number at the top is only as good as what it leaves out — and what it leaves out is never nothing.
| Limit | What it means |
|---|---|
| What this cannot see | The buffer is a normal approximation, and slot returns are not normally distributed — they are heavily skewed by rare large wins, which makes the real distribution worse than this in the middle and better than this in the tail. Treat the answer as a floor rather than a ceiling. The standard deviation is also yours: it is the input this calculator cannot supply, because studios publish volatility as a word. Nothing here is advice on how much to gamble, and no bankroll figure makes a negative-expectation session positive. |
| What it is not | Arithmetic, not advice. Nothing on this page recommends gambling, gambling more, or taking any particular bet, and no calculator turns a negative expectation into a positive one. |
03Put this on
Put this on
your own site.
Free, no account, no charge and no script of ours on your page. The snippet loads the calculator on its own in an inert frame, and keeps an attribution link outside it in your markup.
05Questions about
Questions about
this calculator.
How large does my bankroll need to be to survive a session of this length?
A thousand rounds at 1 per round on a 96% game loses 40 on average, and the swing around that average is the part no folk rule contains: at an assumed standard deviation of 6 per round, ninety-five sessions in a hundred stay inside about 312 of it. The bankroll that survives the session is the two added together — around 352, or 352 times the stake that felt like the risk. Halve the volatility assumption and the buffer halves; quadruple the session length and it only doubles.
What can the bankroll calculator not tell me?
The buffer is a normal approximation, and slot returns are not normally distributed — they are heavily skewed by rare large wins, which makes the real distribution worse than this in the middle and better than this in the tail. Treat the answer as a floor rather than a ceiling. The standard deviation is also yours: it is the input this calculator cannot supply, because studios publish volatility as a word. Nothing here is advice on how much to gamble, and no bankroll figure makes a negative-expectation session positive.
Is the bankroll calculator free to use and embed?
Yes. There is no account, no sign-up and no charge, the page works with JavaScript switched off, and the embed snippet on this page may be pasted into any site. The only thing asked in return is that the attribution link outside the frame is left in place.
Where this arithmetic comes from, and what it is worth.
The formula is printed in full on this page so it can be checked rather than taken. Solaspins asserts no figure of its own here: every number is either one you typed or one derived from it, and the worked example is generated by the same function the form runs. Last checked 2026-08-23. This is arithmetic — not financial, legal or gambling advice.