EV CALCULATOR
For multi-game "same game multi" style promos: work out the expected value of a bonus-back bet across several legs.
| Outcome | You win | Probability |
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How to use this calculator
Choose 3 or 4 legs, then enter your wager, the bonus you'll receive back if one leg loses, and your expected bonus retention (how much of a bonus bet you typically keep). For each leg, enter the back odds and the lay odds.
The calculator works out the three ways the bet can go — all legs win, exactly one leg loses (triggering the bonus), or two-plus legs lose — and combines them into an overall expected value. A positive EV means the promo is worth doing repeatedly.
A worked example
Classic Aussie promo on a multi. Bet on 4 legs, if only 1 misses, they'll refund you a bonus bet.
EV - expected value - is the number that tells you whether this bet is mathematically worth taking over the long run.
A positive EV means the maths is in your favour across many bets; a negative EV means it's against you.
This calculator takes the odds of each leg and any bonus, and works out whether the multi comes out positive or negative once you account for everything.
Feed in your legs and the promo above, and it'll tell you if the boost is actually enough to make the bet worth considering - or whether the bookmaker's margin still has you beat.
When putting in your lay odds, it's most accurate to get them from Betfair right before the event. However, a good estimate is usually 1.1x to 1.2x the back odds, depending on how conservative you want to be. The calculator defaults to 1.1x
What most people get wrong about multis
Here's what bookmakers would rather you didn't dwell on: the vast majority of multis are strongly negative EV. Every leg you add stacks the bookmaker's margin on top of itself, so a big multi is one of the worst-value bets on the board. That's exactly why bookies push them so hard and dangle boosts to make them look tempting.
The only time a multi flips to positive EV is when a promo is generous enough to overcome all that stacked margin - which is what this calculator is really for: checking whether the promo is genuinely worth it, or just dressed up to look that way.
And even when a bet is positive EV, that doesn't mean you'll win it. Positive EV means the odds favour you over many, many bets - any single multi can still lose, and the swings are wild. It's a long-run edge, not a prediction. Treat it as maths, keep your stakes sensible, and never bet money you can't afford to lose.
This calculator and page are general information only and not financial advice. Everyone's circumstances will vary - always do your own research and consult your own financial professionals before making decisions.
Remember - this tool is specifically for matched betting. Matched betting is NOT gambling, and I do not endorse gambling in any way. If gambling is affecting you, in Australia call Gambling Help on 1800 858 858 or visit gamblinghelponline.org.au.