BetMGM vs BetOnline: where their odds disagree
Over the last 30 days, BetMGM and BetOnline quoted the same line at prices that summed to less than 100% on 6 game-markets — a cross-book arbitrage — with an average net edge of 8.18% and a peak of 12.73%. On plain vig, BetOnline is the cheaper book of the two. Last disagreement: Sep 19, 2026.
Vig: BetMGM vs BetOnline
| BetMGM | BetOnline | |
|---|---|---|
| Overall overround | 4.96% | 4.44% |
| Moneyline | 4.45% | 3.06% |
| Spreads | 4.65% | 4.77% |
| Totals | 5.58% | 4.91% |
| NFL | 4.38% | 4.45% |
| MLB | 4.81% | 3.57% |
| NBA | 4.61% | 4.72% |
| NHL | 4.56% | 3.35% |
| MLS | 8.72% | 5.96% |
Disagreements by sport
| Sport | Game-markets | Avg net edge | Max net edge |
|---|---|---|---|
| MLB | 6 | 8.18% | 12.73% |
How big the edges were
Share of detections by net edge bucket. Most cross-book edges are small; the tail is where the money and the execution risk both live.
Recent examples
Best detection per game-market, most recent first. These windows have closed.
| Game | Market | Legs | Net edge | Detected |
|---|---|---|---|---|
| Toronto Blue Jays @ Texas Rangers · MLB | moneyline | Texas Rangers @ BetOnline + Toronto Blue Jays @ BetMGM | 10.66% | Sep 19, 7:18 PM ET |
| Miami Marlins @ Arizona Diamondbacks · MLB | moneyline | Arizona Diamondbacks @ BetMGM + Miami Marlins @ BetOnline | 6.58% | Sep 16, 9:45 PM ET |
| Philadelphia Phillies @ Atlanta Braves · MLB | moneyline | Atlanta Braves @ BetOnline + Philadelphia Phillies @ BetMGM | 7.19% | Sep 13, 1:46 PM ET |
| Tampa Bay Rays @ Texas Rangers · MLB | moneyline | Tampa Bay Rays @ BetOnline + Texas Rangers @ BetMGM | 9.09% | Sep 5, 7:15 PM ET |
| Seattle Mariners @ Boston Red Sox · MLB | moneyline | Boston Red Sox @ BetMGM + Seattle Mariners @ BetOnline | 12.73% | Aug 31, 6:51 PM ET |
| Atlanta Braves @ Milwaukee Brewers · MLB | moneyline | Atlanta Braves @ BetMGM + Milwaukee Brewers @ BetOnline | 2.80% | Aug 23, 7:14 PM ET |
Frequently asked questions
How often do BetMGM and BetOnline disagree?
In the last 30 days our scanner recorded 6 game-markets where BetMGM and BetOnline quoted the same line at prices whose implied probabilities summed to less than 100% — a cross-book arbitrage — across 6 scans. The average net edge was 8.18% and the largest 12.73%.
Which has lower vig, BetMGM or BetOnline?
BetOnline — BetMGM measures 4.96% overall and BetOnline measures 4.44% over 30 days of live lines. The per-market and per-sport breakdown is in the table above.
Does this mean I can make money betting both?
Not automatically. These are measurements of past disagreements at the moment they were detected. Lines move within minutes, displayed prices may not be available at your stake, both books must be accessible in your state, and neither book has to honor a stale price. ArbMonster shows the math; the execution and the risk are yours.
Which sports do BetMGM and BetOnline disagree on most?
MLB (6 game-markets, avg 8.18%).
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