BSP — Where No Single Bookmaker Holds the Pen
The Betfair Starting Price is a fundamentally different creature from the traditional SP. Where the bookmaker SP is derived from a sample of prices offered by firms with a built-in profit margin, BSP is generated by the exchange market itself — a peer-to-peer ecosystem where backers and layers set the price through supply and demand. The exchange price nobody sets — the market does.
The scale of the BSP dataset is considerable. Analysis from Betfair’s own hub covers 381,776 races and over 3.2 million individual runners, across which BSP implied probability has tracked actual winning probability with remarkable accuracy. That alignment — close to 1:1 across the full price range — is what separates BSP from bookmaker SP, where the overround systematically compresses longer prices and inflates shorter ones.
Understanding how BSP is formed, what its guardrails are, and where its limitations lie is essential for any punter considering the exchange as an alternative to traditional SP betting.
How BSP Is Formed: The Matching Algorithm
BSP is not simply the last traded price before the off. It is a calculated price, derived from the pool of unmatched back and lay orders that exist in the exchange market at the moment the race starts.
Throughout the pre-race period, punters place back bets (betting on a horse to win) and lay bets (betting against a horse) at various prices. Some of these bets are matched — a back order at 5.0 meets a lay order at 5.0, and the bet is struck. Others remain unmatched because no counterparty is willing to meet the requested price. At the off, the matching algorithm processes all remaining unmatched orders and determines a single clearing price: the BSP.
The algorithm works by finding the price at which the maximum volume of unmatched bets can be crossed. It aggregates all back orders from the highest price downward and all lay orders from the lowest price upward, looking for the point where supply meets demand. This is conceptually similar to how stock exchanges determine opening prices — a volume-weighted equilibrium.
The result is a price that reflects the genuine balance of opinion in the market, free from the bookmaker’s overround. In a liquid market with substantial volume on both sides, BSP is an efficient price — arguably more efficient than bookmaker SP because it is not inflated by margin. In a thin market with few participants, BSP can be volatile and less reliable, because a small number of orders can disproportionately influence the clearing price.
One crucial detail: orders placed as “Take BSP” (sometimes called “BSP orders”) are not visible in the pre-race order book. They are held separately and only enter the calculation at the moment of the off. This means the pre-race exchange price — what you see on screen — is not identical to the BSP. The final BSP can be higher or lower than the last traded price, depending on the volume and direction of BSP orders.
Near Price and Far Price: The BSP Guardrails
To help punters understand the likely range of the BSP before it is struck, Betfair provides two indicative figures: the Near Price and the Far Price.
The Near Price is the BSP estimate if only the currently visible unmatched orders were used in the calculation. It is the tighter, more conservative estimate — the price the market would clear at if no additional BSP orders were submitted. The Far Price includes an estimate of the likely BSP orders (which are hidden until the off) and represents the wider boundary. The actual BSP will typically fall between these two figures, though it is not guaranteed to do so.
The gap between Near and Far Prices is itself informative. A narrow gap suggests the market is well-formed, with plenty of liquidity on both sides and little uncertainty about the final price. A wide gap suggests thin liquidity or an imbalanced order book, where the BSP could land at a significantly different level depending on the hidden BSP orders. Races at major meetings — Saturday afternoon at Ascot or Cheltenham — tend to have narrow Near/Far gaps. Midweek all-weather cards at smaller tracks often show wider gaps, reflecting the same liquidity challenges that affect bookmaker SP quality.
For practical purposes, the Near Price is the more useful reference point if you are deciding whether to take BSP or place a limit order. If the Near Price offers acceptable value, BSP is likely to settle in a range you can live with. If the Near Price is significantly shorter than you need, the Far Price gives you an optimistic upper bound — but relying on it is speculative.
Minimum Stakes and Unmatched Bet Conversion
BSP has a minimum stake requirement. The minimum BSP back stake on Betfair is £2 (the standard exchange minimum is £1, but BSP bets have a higher threshold). This is lower than the minimum for many bookmaker SP bets in practice, making BSP accessible to small-stakes punters who want exchange pricing without the complexity of placing limit orders.
One of BSP’s most useful features is unmatched bet conversion. If you place a back bet at a specific price — say, 6.0 — and it is not matched before the off, you can instruct Betfair to automatically convert it to a BSP bet. The bet will then be filled at whatever the BSP turns out to be, provided the BSP is at or below a limit you set. This “keep” or “take BSP” option is a safety net: you attempt to get your preferred price, and if the market does not cooperate, you fall back to BSP rather than missing the race entirely.
The structural advantage of BSP over bookmaker SP lies in the overround — or rather, the near-absence of it. Modelling by On Course Profits shows BSP operating with an aggregate overround close to 100%, compared with approximately 130% for bookmaker SP. The difference is most pronounced at longer prices, where bookmaker SP compresses returns most aggressively. A horse at bookmaker SP 20/1 might return 25/1 or more at BSP, because the exchange does not embed the same margin into its price.
The trade-off is commission. Betfair charges a percentage on net winnings — typically between 2% and 5% depending on your account status. This commission replaces the overround as the cost of betting. For most punters betting at prices above 5/1, the commission is materially less than the overround they would pay at bookmaker SP. At very short prices — Evens and below — the advantage narrows, and bookmaker SP with Best Odds Guaranteed can sometimes be competitive.
BSP Limitations and When to Use Limit Orders Instead
BSP is not a universal solution. Its limitations become apparent in specific conditions that every exchange user should recognise.
Thin markets are the primary risk. In races with low exchange volume — midweek all-weather fixtures, minor meetings, or races with very small fields — the BSP can settle at a price that looks anomalous. A handful of large orders in one direction can push the clearing price away from the “true” market. In these conditions, a limit order at a specific price gives you control that BSP does not.
Lay-side exposure is another consideration. If you are laying a horse at BSP, your liability is unknown until the price is struck. A horse that looks like a 4.0 lay on the Near Price could settle at 6.0 or higher if hidden BSP back orders flood in at the off. Professional layers almost always use limit orders to cap their exposure, reserving BSP for small-stake or low-risk situations.
Finally, BSP does not offer Best Odds Guaranteed. With a bookmaker, you can take a fixed price and receive the SP if it is higher. With BSP, you get one price: the calculated clearing price at the off. There is no floor and no ceiling. If you value the insurance of BOG — particularly on short-priced runners where the bookmaker overround is low — a traditional bookmaker bet may deliver better expected value than BSP. The exchange price nobody sets is also the exchange price nobody guarantees.