Roulette bet calculator

Click the layout to place chips — numbers, splits, corners, dozens or colours in any mix. The calculator adds up your stake, counts how many of the 37 numbers return something, shows the result on every number, your average loss per spin and your chance of being ahead after 10, 100 or 1,000 spins.

Payouts, bet spots and table limits come straight from the rules of our game. The calculator accepts exactly the 157 bets the Rotunda of Shai does and warns you when a set would break a table limit.

• Total stake — everything on the cloth for one spin.
• Numbers covered — on how many of the 37 numbers at least one of your bets wins. More is not better in itself: the more you cover, the smaller each win.
• Something comes back and you finish the spin ahead are different things. Red with a chip on the first four covers 20 numbers, but on two of them only part of the stake returns.
• Average result per spin is always −2.70% of your stake, whatever you build. That is the house edge at work; the calculator works it out number by number, so you do not have to take our word for it.
• What every number does to you groups the 37 pockets by result. The layout shows the same with coloured strips: turquoise where you finish ahead, amber where part of the stake comes back.
• After a series of spins — your chance of being ahead, exactly even or behind after 10, 100 or 1,000 spins with the same bets. Where we can, we compute it exactly (a binomial distribution or a spin-by-spin convolution); otherwise your browser plays out 20,000 series.

A popular way to “insure” red against zero is 1,000 on red and 100 on the corner 0–1–2–3. Stake: 1,100.

Something comes back on 20 numbers (54.1%), yet you finish ahead on only 18 (48.6%) — exactly as with red alone. The corner turns a 1,000 loss into a 200 loss on zero and on 2 and costs 100 on every other spin. The average is −29.73 per spin: 2.70% of 1,100.

Put 200 on the corner instead and zero becomes a small win (+600), but the black numbers now cost 1,200. Over 100 spins the first set is ahead 38.6% of the time and the second 38.0%. The insurance moves results around; it does not improve them.

1,000 on the first dozen and 1,000 on the second cover 1 to 24. Any of those 24 numbers returns 3,000 for your 2,000 (+1,000); the other 13 — 25 to 36 and zero — cost 2,000. You win almost two spins in three (64.9%).

That feels safe, and over a short evening it often is: after 10 spins you are ahead 51.0% of the time. But every loss wipes out two wins, and the average of −54 per spin keeps working. After 100 spins your chance of being ahead is 37.0%; after 1,000 it is 11.8%.

A combination with a famous name: 1,400 on 19–36, 500 on the line 13–18 and 100 on zero — 2,000 in all, within the Scribes’ Table limits. It covers 25 numbers and wins on every one of them: +800 on 19–36, +1,000 on 13–18, +1,600 on zero. Only 1 to 12 lose, and they cost the full 2,000.

You finish ahead on 67.6% of spins, more often than with any single bet on the table. Yet the average is −54 per spin, as for any 2,000 on the cloth, and one loss wipes out two or three wins. After 10 spins you are ahead 43.4% of the time, after 100 spins 34.7%, after 1,000 spins 10.3%. Press “James Bond” above the layout and check it yourself.

Put a single 100 chip on 17 and set the series to 100 spins. You are ahead in 50.9% of series — more often than with 1,000 on red (35.5%). There is no trick: three hits in 100 spins already bring you to +800, and with a 1 in 37 chance per spin, three or more hits happen in about half of all series.

The average, though, is the same −2.70%: −270 over 100 spins of 100. The difference is in the shape. Red gives you lots of small results drifting slowly downwards; a single number gives you long losing runs broken by rare big wins. Neither changes the maths, which is why the calculator always shows both your chance and your average.

Switch between the Scribes’, Priests’ and Pharaoh’s tables and the calculator converts your bets into that table’s chips — the tables differ exactly tenfold. If a set would not be accepted in the game (more than 1,000 on one number at the Scribes’ Table, more than 5,000 on an outside bet, more than 10,000 per spin), you see a warning, just as you would at the table.