# Arbitrage calculator (2 and 3 way)

> Independent. Not affiliated with, endorsed by or sponsored by Novig.

Canonical: https://novigapi.com/arbitrage-calculator
Method checked: 2026-11-12
Interactive tool: https://novigapi.com/arbitrage-calculator (prefill with ?a=&b=)

An arbitrage exists when the implied probabilities of all outcomes at the best prices add up to less than 100%. +105 and +102 sum to 98.29%, so $1,000 split $495.66 / $504.34 returns $1,017.38 either way. On Novig, add the live taker fee of 0.06 x P x (1 - P) per $1 (Novig docs, checked 12 Nov 2026).

## Worked example

Worked examples, $1,000 total stake

| Market | Implied sum | Stakes | Returns | Profit |
| --- | --- | --- | --- | --- |
| +105 / +102 | 98.29% | $496.31 / $503.69 | $1017.44 | $17.44 |
| 3.20 / 3.60 / 3.40 | 88.44% | $353.35 / $314.09 / $332.56 | $1130.72 | $130.72 |

```
implied sum = 1/D1 + 1/D2 (+ 1/D3)
stake_i = total x (1/D_i) / implied sum
return = total / implied sum
```

Stakes are split in proportion to each outcome's implied probability, so every result returns the same amount. When the implied sum is under 100%, that amount is more than the total staked.

## Arbitrage with an exchange leg

An exchange price is often the best price on one side, because it carries no vig. On Novig, a pregame fill on a game market pays no fee, but a live taker fill pays 0.06 x P x (1 - P) per $1 of payout. Tick the Novig box on that leg and the tool uses the fee-adjusted price. A thin arb can vanish once the fee is in.

> Books limit accounts that arb often, and a price can move before both legs fill. Place the leg most likely to move first.

## How to use it

1. Pick 2 way or 3 way.
2. Enter the best price for each outcome and tick any leg that is a live Novig taker fill.
3. Enter the total stake to see each stake, the return and the profit.

## Questions

### How do you calculate arbitrage betting?

Add 1 / decimal odds for every outcome. If the sum is below 1, stake each outcome at total x (1 / its odds) / the sum.

### Is arbitrage betting legal?

In the US it is legal to bet both sides at different books, but books can limit or close accounts that arb.

### Do fees kill arbs on Novig?

Pregame fills on game markets carry no fee. Live taker fills do, and that can remove a margin of 1-2%.

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