LARO77 Sports Arbitrage: The Sure Bet Formula and Its Limits
Sports arbitrage backs every outcome of a market at different books so the implied probabilities sum to under 100%.
Key facts and contents
- LARO77 DNB Meaning
- DNB means draw no bet: a two-way bet on a three-way game in which your stake is returned if the match is drawn.
- LARO77 ATS Meaning
- ATS means against the spread: a team's record counted by whether it covered the handicap, not whether it won.
- LARO77 First Blood
- First blood is an e-sports market on which team scores the first kill of a map.
- LARO77 Level Ball
- Level ball is an Asian handicap of 0, also written 0.0 or pick.
- LARO77 NBA Spread
- An NBA spread gives the favourite a minus number and the underdog the same number as a plus.
- LARO77 Win Rate
- Divide 1 by the decimal price to get the win rate you need to break even: 1.91 needs 52.4%, 2.00 needs 50% and 3.00 needs 33.3%.
- LARO77 Walkover
- A walkover is a tennis match that never starts because one player withdraws; a retirement is a match that starts and is not finished.
Sports arbitrage is the idea of backing every outcome of one market at different bookmakers so the implied probabilities add up to under 100%, which on paper locks in a profit whichever side wins.
This page works the formula with labelled example prices, then explains why it rarely survives contact with real bookmakers. It does not recommend the method and makes no promise of profit. It sits inside this site’s sports betting markets pillar. 21+ only.
Sports arbitrage: the formula
Convert each best price to an implied probability, 1 ÷ price, and add them. A normal bookmaker market adds to more than 100% because of the margin. If the best prices across two books add to under 100%, the gap is an arbitrage. The same margin idea is explained in the house edge definition.
Stakes are split in proportion to each implied probability, so every outcome returns the same amount. For total outlay T, stake on outcome i = T × (1 ÷ price i) ÷ (sum of all 1 ÷ price).
A sure bet worked example
A sure bet is the trade-name for an arbitrage in which every outcome is covered. Take a two-way market with example prices from two different books: 2.10 on one side at Book A, 2.05 on the other at Book B.
| Step | Side at 2.10 | Side at 2.05 | Total |
|---|---|---|---|
| Implied probability (1 ÷ price) | 0.4762 | 0.4878 | 0.964 |
| Share of outlay | 0.4762 ÷ 0.964 = 49.4% | 0.4878 ÷ 0.964 = 50.6% | 100% |
| Stake on ₱1,000 outlay | ₱494 | ₱506 | ₱1,000 |
| Return if this side wins | 494 × 2.10 = ₱1,037 | 506 × 2.05 = ₱1,037 | n/a |
Either way the return is about ₱1,037 on ₱1,000 out, a profit of about ₱37, which is 3.7% of the outlay (1 ÷ 0.964 − 1 = 0.037). A market with a third outcome, such as a 1X2 with a draw, needs a third stake. Everything about it is paper arithmetic: the profit exists only if both bets are accepted at exactly these prices and settle the way you assume.
Why the sure bet rarely survives
Each line below is a problem you can meet and what to do about it, which in most cases is to stop.
The price moves between your two bets
Place the first bet and the second price shortens, say from 2.05 to 1.95. The sum becomes 1/2.10 + 1/1.95 = 0.989, and the gap shrinks to 1.1%, then closes. If it flips above 100%, you hold one side with no cover. Do not chase the second leg at a worse price.
Stake limits cap the leg you want
A sportsbook can cap the stake it accepts on a market. If one leg accepts ₱300 when the arithmetic needs ₱494, the proportions break and one outcome pays far more than the other. Read the limits on the screen before the first leg.
One bet is voided or re-priced
Obvious-error and palpable-error rules let a sportsbook void or re-price a bet placed at a mistaken price. A voided leg leaves the other side naked. Read the sportsbook’s rules page for error handling.
The same market settles differently
One book counts overtime and the other does not. One refunds a level result and the other loses it. Compare the two rules pages line by line; the general convention differs by sport, as for a tennis walkover or a half-point NBA spread.
Offers and withdrawals carry conditions
Money held under a promotion can carry turnover conditions that the arbitrage stakes do not satisfy. Read the withdrawal conditions on the deposit and withdrawal screens before you rely on any return.
The account gets restricted
Bookmakers can limit or close accounts, and a limited account takes smaller stakes at worse prices. The profit per round is small, 3.7% in the example, so a few restricted rounds cost more than they earn.
What to take from the arithmetic
Treat the 3.7% as an illustration of how thin the gap is, not as an opportunity. A margin of 104% across both books is the normal case, and the useful skill is reading it: if the implied probabilities sum to over 100%, the market costs you the difference on average.
Before any bet, set a stake limit and stop at it. If betting is costing more than you planned, the responsible play page lists tools to limit your own play.
FAQ
What is sports arbitrage?
It is backing every outcome of one market, usually at different bookmakers, when the best prices imply probabilities that sum to under 100%. The stakes are split in proportion so each outcome returns about the same.
Is an arbitrage bet really risk free?
Only on paper. A price can move between your two bets, a stake can be capped, a bet can be voided or re-priced, and the two books may settle the same market differently. Any of these can leave you with a loss.
Does this site recommend sports arbitrage?
No. This page explains the arithmetic and why it rarely holds up. It makes no promise of profit, and nothing here is a tip. Stake only what you can afford to lose, and 21+ only.