Understand how arbitrage betting works, why guaranteed profits are mathematically possible, and how to calculate stakes step by step — with real examples.
New to this? Start with:No-Vig Odds Guide
You check FanDuel and see Chiefs at -110 (1.909 decimal). Then you open DraftKings and see Bills at +120 (2.200 decimal). You like both sides for different reasons — but what if you could bet both and guarantee a profit no matter who wins?
That is arbitrage betting. And it works when the math adds up to less than 100%.
Ready to run the numbers? Use the arbitrage calculator to enter odds from two or more outcomes across sportsbooks and instantly see your stake split and guaranteed profit.
An arbitrage (or "arb") exists when two sportsbooks price the same event differently enough that the combined implied probabilities drop below 100%. The gap between the total and 100% is your guaranteed profit.
Let's check our example:
| Sportsbook | Outcome | American Odds | Decimal | Implied Probability |
|---|---|---|---|---|
| FanDuel | Chiefs win | -110 | 1.909 | 52.38% |
| DraftKings | Bills win | +120 | 2.200 | 45.45% |
Total implied probability: 52.38% + 45.45% = 97.83%
Since 97.83% < 100%, this is an arb. Your guaranteed profit = 100% - 97.83% = 2.17% of your total stake.
If your odds are in American format:
For each leg: 1 / decimal odds
52.38% + 45.45% = 97.83%
Below 100% = arb opportunity. Above 100% = no opportunity (the house has an edge on both sides).
With a $1,000 total stake:
Not a massive return, but it is risk-free. That is the trade-off with arbs — low return, zero risk.
You cannot just split your stake 50/50. Each leg needs a specific amount so you profit the same regardless of which outcome wins.
Formula: Stake_i = Total Stake × (1 / d_i) / arb_sum
Where arb_sum = sum of (1 / d_i) for all legs.
With $1,000 total:
| Leg | Decimal | 1/d | Stake | Payout if Wins |
|---|---|---|---|---|
| Chiefs (FanDuel) | 1.909 | 0.5238 | $1,000 × 0.5238 / 0.9783 = $535.43 | $535.43 × 1.909 = $1,022.17 |
| Bills (DraftKings) | 2.200 | 0.4545 | $1,000 × 0.4545 / 0.9783 = $464.57 | $464.57 × 2.200 = $1,022.05 |
Either way, you get back about $1,022 on a $1,000 investment. Profit: ~$22, guaranteed.
Tip: Use the Arbitrage Calculator instead of doing this math by hand. Enter the odds and your total stake, and it shows the exact amount to place on each leg.
Arbitrage is theoretically risk-free, but execution is not:
Account restrictions. Sportsbooks monitor for arb patterns and may limit your stakes or close your account. This is the biggest practical barrier.
Odds movement. Lines change fast. By the time you place both bets, one side may have shifted. A 2% arb can disappear in seconds.
Maximum bet limits. Books often cap stakes on sharp lines, preventing you from placing your calculated amount.
Capital requirements. Arbing ties up money across multiple sportsbooks. A 2% return on $1,000 is $20 — you need significant volume or capital to make meaningful income.
Rounding and fees. Small arb margins can be wiped out by withdrawal fees or rounding errors in your stakes.
Tip: Treat arb betting as one tool in your overall strategy, not a standalone income source. The real value of arb awareness is that it sharpens your sense of when markets are mispriced — and that skill transfers directly to +EV betting.
Arbitrage betting (arb betting) means placing bets on all outcomes of an event across different sportsbooks. When the combined implied probabilities total less than 100%, you guarantee a profit regardless of the result.
Add the inverse of each outcome's decimal odds (1 / decimal odds). If the sum is less than 1 (arb percentage below 100%), an opportunity exists.
Each leg stake is proportional to its share of the total implied probability. The formula is: Stake_i = Total Stake x (1/d_i) / (arb%). Our calculator shows the exact amount per leg.
Yes, arbitrage betting is legal in most jurisdictions. However, sportsbooks may limit or close accounts of known arb bettors. Always check local regulations and the terms of each sportsbook.
The arb percentage is the sum of implied probabilities across all legs. A value below 100% means guaranteed profit is available. A 97% arb means a 3% guaranteed return.