Hold Percentage on MLB Props: How Much the UK Books Are Taking

The Bet I Could Not Stop Losing on Even With a Real Edge

I had a stretch a few years back where I was confident I had found genuine edge on a hits prop market. The model said the over was a 56 per cent winner. The price said the over was implied at 53 per cent. On paper that was a 3-point probability edge – a clean +EV bet by any honest measure. I bet it for two months. I lost. Not by a lot, not by a little, but consistently below break-even. The model was right. The probability work was right. What I had missed was the hold. The book was running roughly 12 per cent overround on that specific market, and the 3-point edge I thought I had was being eaten alive by the structure of the price itself.

That experience permanently changed how I read MLB prop prices. The headline odds are not the bet you are making. The bet you are making is the price net of the hold the book is taking. Two markets at the same nominal price can carry very different effective costs to the punter, and the punter who does not know how to spot the difference is paying a tax they did not plan for.

What Hold Actually Means

Hold percentage – also called overround, vig, or juice – is the share of every pound staked that the bookmaker keeps on average if betting volume is balanced across both sides of a market. It is the structural cost of being a bookmaker’s customer. On a perfectly priced two-way market with no overround, the two implied probabilities sum to 100 per cent. On a real market the two implied probabilities sum to more than 100 per cent, and the excess is the hold.

The maths is mechanical. For a strikeout over priced at 1.83 and an under priced at 1.91, the implied probabilities are 1/1.83 = 54.6 per cent and 1/1.91 = 52.4 per cent. Their sum is 107 per cent. The 7 per cent excess is the overround. The “hold” the book theoretically keeps is that 7 per cent on every balanced pound of action, distributed across both sides of the market.

The point of the calculation is not academic. The hold is the headwind the bettor faces before any analysis is run. On a market with 7 per cent hold, the punter has to be right more often than the implied probability to break even, because the implied probabilities have been inflated above true probability by the hold. Beating a 7 per cent market is harder than beating a 4 per cent market by exactly the difference between the two.

Why Prop Hold Is So Much Higher Than Moneyline Hold

The structural difference between main markets and prop markets is the source of the hold gap. Moneyline and run line markets attract the bulk of betting volume, are heavily traded between books, and respond quickly to sharp action. Books cannot sustain wide overrounds on those markets without losing volume to competitors. The result is that UK MLB main markets typically run with overrounds in the 5 to 8 per cent range – narrow, competitive, and tightly priced.

Player props are different. Volume per individual prop is small, sharp action is harder to spot in the noise, and the cost of mispricing is lower because total exposure on any one prop is limited. Books can afford to run wider overrounds on these markets without losing competitive position. UK MLB prop hold percentages typically land in the 8 to 15 per cent band, with the longer-tail markets – over-2.5 hits, exact-outcome props, multi-stat parlays – sometimes running wider still.

Peter Jackson, the chief executive of Flutter Entertainment whose UK-facing brands include Sky Bet and Paddy Power, has pointed to the importance of the US-style prop product to the group’s earnings profile, noting in a quarterly statement that “FanDuel continues to win in the US.” The product travelling well commercially is the same product that runs wider overrounds; that wider overround is part of why prop markets are profitable for the operators who run them at scale.

Calculating Hold From Decimal Odds

The two-line calculation is the workflow. Take both decimal prices on a two-way market. Calculate 1/odds for each. Sum them. Subtract 100 per cent. The remainder is the overround. For a two-way prop with prices 1.80 and 2.00, the calculation is 1/1.80 + 1/2.00 = 55.6 + 50.0 = 105.6 per cent, giving 5.6 per cent overround. For prices 1.65 and 2.10, it is 60.6 + 47.6 = 108.2, giving 8.2 per cent. For prices 1.50 and 2.30, it is 66.7 + 43.5 = 110.2, giving 10.2 per cent.

The pattern across these examples is worth noting. Tighter pricing on both sides of a market – both lines closer to even money – tends to produce narrower overrounds. Wider pricing – one favourite-style price on one side, longshot on the other – tends to produce wider overrounds even when the two prices look balanced superficially. The same pattern shows up across UK MLB prop markets: the closer the two-way prices sit to even, the more efficient the market typically is.

For one-way markets that do not have a public other side – many anytime HR markets are listed only as the over without a quoted under – the hold cannot be calculated from price alone. The punter has to compare across books to estimate the implied fair price, then back out the hold from there. This is where line shopping does double duty: it identifies the cheapest price and exposes the rough overround on a market that does not show its full structure.

Which UK Books Run Tighter

The hold percentages run differently book by book and category by category. Across the UK MLB prop landscape I would describe the spread broadly. The traditional fixed-odds books tend to run narrower holds on high-volume props – strikeouts and HR being the obvious examples – and wider on low-volume props. The exchange-style platforms, where punters trade against each other rather than against the book, run a commission rather than an overround, which functions differently but produces a comparable cost structure once commission is netted out. Some niche books run uniformly wide holds across all props.

The right way to know which books run which holds on the markets you actually bet is to do the calculation yourself across two or three weeks of price snapshots. Pull the prices on a sample of strikeout, total bases, and HR props from each book at the same time on the same day. Run the overround calculation on each. The pattern that emerges is durable across months and is the foundation of where to send your action long-term.

The MLB-FanDuel partnership announced in 2023 changed the international prop landscape because it cemented the prop-heavy US format as the template that international books increasingly mirror. UK books that have leaned into prop-rich slates have done so partly to capture interest from the same kind of punter who is finding MLB through London Series coverage and TNT Sports broadcasts of 15 games a season. The wider hold is the price of accessing the deeper menu.

What to Do With the Hold Number Once You Have It

The practical use of the hold is twofold. First, it sets the threshold for what counts as a real edge. On a 5 per cent hold market, a 3 per cent +EV calculation is meaningful. On a 12 per cent hold market, a 3 per cent +EV calculation is sitting much closer to the noise floor of your model – the price is being shaded enough that small calibration errors in your probability work eat the edge. The same nominal edge is not the same real edge across markets.

Second, it directs which markets you should actually bet. A market with a 12 per cent hold is not impossible to beat, but it is harder. A punter with limited time to research and a model that has not been calibrated across years should focus on the lower-hold markets where the structural headwind is smaller. Strikeout overs, F5 totals, and run lines tend to sit at the narrower end of the hold band. The longer-tail props tend to sit at the wider end. Allocating research time accordingly is one of the simpler ways to improve long-run prop ROI.

Written by the editors at BasePropPro.