Roulette Martingale Calculator
Next bet and risk after losses with American odds.
What it does
Martingale doubles after each loss to recover with one win. Three $5 losses risk $35 and demand $40 next. The math grows fast while odds of long streaks fall slowly.
The tool above takes base bet and consecutive losses and returns next bet, total lost, and streak chance. The defaults 5 and 3 match the worked example, so the page opens showing $40.00.
Next is base times 2 to losses. Lost sums base times (2 to losses minus 1). Streak chance is (20/38) to losses for American red/black with two greens. Here (20/38)^3 is 14.58 percent, far from rare.
Use this to size bankrolls and table limits before starting. Caps stop the chain: ten losses need 1024x base, which tops most limits and stomachs.
This page shows the formulas, one full hand checked example at $5 with 3 losses, a reference table, and practice checks that run through the tool.
How to use
- Type base bet in dollars.
- Type consecutive losses 0 to 10.
- Read Next bet as base times 2^losses.
- Read Lost so far as base times (2^losses minus 1).
- Read Streak chance on American wheels.
- Check table limit covers next bet.
Formula
- base
- Starting bet dollars.
- k
- Consecutive losses, whole 0-10.
- 20/38
- Loss prob per American red/black spin.
Caps at 10 losses here (1024x). European single zero uses 19/37 per spin instead.
Worked example
Example: $5 base, 3 losses
Three straight losses on $5 red bets. Find next and risk.
- Power: 2^3 = 8.
- Next: 5 x 8 = $40.00.
- Lost: 5 x (8 minus 1) = 5 x 7 = $35.00.
- Prob: (20/38)^3 = 0.1458 = 14.58 %.
- Check: 35 + 40 = 75 to recover plus 5 profit on win.
- Table limit must allow $40.
Reference table
| Losses | Next | Lost |
|---|---|---|
| 0 | $5.00 | $0.00 |
| 3 | $40.00 | $35.00 |
| 5 | $160.00 | $155.00 |
Limits
- American red/black odds here (20/38 loss).
- Losses 0 to 10 capped.
- No table limits modeled. Check max bet.
- Expectation stays negative. Math, not an edge.
Common mistakes
- Thinking doubling overcomes house edge.
- Forgetting total risked tops next bet near double.
- Using European 19/37 with American 20/38.
- Chasing past table max.
- Reading streak chance as win chance.
Try it yourself
Quick checks. Answers sit tucked under each question.
Base $10, 0 losses?
Next $10.00, lost $0.00, chance 100.00 %.
Base $5, 5 losses?
Next $160.00, lost $155.00, chance 4.04 %.
Questions
$5 after 3?
Bet $40 next, $35 lost.
Streak odds?
(20/38)^k. Here 14.58 %.
Profit on win?
Base profit if bankroll holds.
Table max?
Check before starting. Caps kill chains.
European?
Uses 19/37. Not here.
Edge?
No. Negative expectation remains.