Horse racing Win: arbitrage calculator
- Market
- 6-way
- Typical overround
- 10%–25%
- Sample arbitrage return
- -1.70%
- Profit on every outcome
- -1.70
- Total stake
- 100.00
- Sum of implied probabilities
- 101.73%
| Leg | Odds used | Effective odds | Stake |
|---|---|---|---|
| Back Runner 1 | 3.200 | 3.200 | 30.72 |
| Back Runner 2 | 4.200 | 4.200 | 23.41 |
| Back Runner 3 | 5.000 | 5.000 | 19.66 |
| Back Runner 4 | 7.500 | 7.500 | 13.11 |
| Back Runner 5 | 12.000 | 12.000 | 8.19 |
| Back Runner 6 | 20.000 | 20.000 | 4.92 |
| If this wins | Legs that pay | Gross return | Commission | Net profit |
|---|---|---|---|---|
| Runner 1 | Runner 1 | 98.30 | 0.00 | -1.70 |
| Runner 2 | Runner 2 | 98.30 | 0.00 | -1.70 |
| Runner 3 | Runner 3 | 98.30 | 0.00 | -1.70 |
| Runner 4 | Runner 4 | 98.30 | 0.00 | -1.70 |
| Runner 5 | Runner 5 | 98.30 | 0.00 | -1.70 |
| Runner 6 | Runner 6 | 98.30 | 0.00 | -1.70 |
No arbitrage: -1.70% return
Win markets in horse racing have overrounds that grow with the number of runners. Non-runners trigger deductions under Rule 4, which change every remaining price after the fact and can undo an arbitrage.
Market structure
Horse racing Win has 6 outcomes (
Runner 1, Runner 2, Runner 3, Runner 4, Runner 5, Runner 6). Bookmakers typically price it with an overround between 10% and
25%, more for fields with many runners. For an arbitrage you need prices from at least two books whose implied probabilities, taken at the best price per outcome, add up to less than 100%.
Worked example
Two books quote 3.00 / 4.00 / 5.00 / 7.00 / 12.00 / 20.00 and 3.20 / 4.20 / 5.00 / 7.50 / 11.00 / 18.00. Taking the best price for each outcome (3.20 / 4.20 / 5.00 / 7.50 / 12.00 / 20.00) gives an implied sum of 101.73%. Arbitrage: no, return -1.70%. The calculator above is pre-filled with those best prices; the stakes for 100 in total are 30.72 / 23.41 / 19.66 / 13.11 / 8.19 / 4.92.
| Outcome | Book A | Book B | Best | Stake of 100 |
|---|---|---|---|---|
| Runner 1 | 3.00 | 3.20 | 3.20 | 30.72 |
| Runner 2 | 4.00 | 4.20 | 4.20 | 23.41 |
| Runner 3 | 5.00 | 5.00 | 5.00 | 19.66 |
| Runner 4 | 7.00 | 7.50 | 7.50 | 13.11 |
| Runner 5 | 12.00 | 11.00 | 12.00 | 8.19 |
| Runner 6 | 20.00 | 18.00 | 20.00 | 4.92 |
Multi-way specifics
Outright and win markets have many runners, and the arbitrage usually spans several books. Dead-heat rules and each-way terms differ by book, so read the settlement terms before assuming a price is what it appears.
Frequently asked questions
How many legs does a Horse racing Win arbitrage need?
One per outcome: 6 legs covering Runner 1, Runner 2, Runner 3, Runner 4, Runner 5, Runner 6. Every outcome must be backed for the position to profit whatever happens.
How large is the overround in Horse racing Win?
Typically 10% to 25% at a single book. An arbitrage needs the best prices across books to sum below 100%, so the gap between books has to exceed the margin.
Is the worked example on this page a real arbitrage?
The sample prices give an implied sum of 101.73% at the best price per outcome (arbitrage: no). They are illustrative; live prices change constantly.
What can go wrong with an arbitrage across 6 outcomes?
A leg not being available at the assumed price, a void or push on one leg, different settlement rules between books, and stake limits that stop you placing the full amount.