Closing line value in horse racing is most cleanly measured against the Betfair Starting Price (BSP), the price the exchange strikes for each runner at the jump: CLV = your price / BSP - 1. With illustrative prices, a $6.00 bet on a runner whose BSP turns out to be $5.00 is 6.00 / 5.00 - 1 = +20% CLV. A $6.00 bet on a runner that starts at $6.80 is 6.00 / 6.80 - 1 = -11.8%.
BSP works as the racing close because it is struck at the jump, with the pre-race news and money in and no bookmaker margin. Beat it on average over a few hundred bets and your prices are better than the market's final view, whatever the results say. Closing line value covers the method for every sport.
Why BSP works as the racing closing line
- It is set at the jump. The exchange works it out when the market is suspended at the start, from the bets waiting to take the starting price and the unmatched bets on each side. Every scratching is known by then and the pre-race money is in. Betfair Starting Price explains the reconciliation.
- It has no bookmaker margin in it. Punters set the prices on both sides and the exchange earns from commission, not the price, so a race's BSPs add up much closer to 100% than a bookmaker's market.
- Each runner's BSP comes from a fixed process, so there is no flattering close to pick after the race.
- You could have had it. Backing at BSP is the do-nothing alternative to an earlier price, so beating it says your timing beat waiting.
The limits: in a race where little money traded on the exchange, BSP says less; not every race may have one; and commission changes what taking it would have paid.
Working out CLV against the Betfair Starting Price
In chances, the $6.00 bet implies 1 / 6.00 = 16.7% on a runner the market's last view put at 1 / 5.00 = 20.0%. With illustrative prices:
| Price taken | BSP | CLV |
|---|---|---|
| $6.00 | $5.00 | +20.0% |
| $6.00 | $6.80 | -11.8% |
| $3.20 | $3.00 | +6.7% |
| $15.00 | $11.50 | +30.4% |
Long prices throw up big CLV figures both ways, because a few dollars at $15.00 is a small change in chance: 1 / 15.00 = 6.7% against 1 / 11.50 = 8.7%. Read a record by its average, not its biggest rows.
A race's BSPs rarely add to exactly 100%. If they come to, say, 100.5% (illustrative), scale your runner's BSP by that total: 6.00 / (5.00 x 1.005) - 1 = 19.4%.
Adjusting BSP for exchange commission
The exchange takes its commission from your net winnings on each market, and it sets the rate, so these examples treat 7% as an illustrative input; exchange commission covers how it is charged. A winning $1 bet at BSP returns the net BSP:
net BSP = 1 + (BSP - 1) x (1 - commission rate) = 1 + (5.00 - 1) x (1 - 0.07) = $4.72
Which figure to use depends on the question:
| Question | Compare with | The $6.00 bet against a $5.00 BSP |
|---|---|---|
| Did my price beat the market's final view of the chance? | The BSP before commission | 6.00 / 5.00 - 1 = +20.0% |
| Did my bookmaker bet beat taking BSP on the exchange? | The net BSP | 6.00 / 4.72 - 1 = +27.1% more returned if it wins |
| I backed on the exchange: did I beat BSP? | Net price against net BSP | (1 + (6.00 - 1) x 0.93) / 4.72 - 1 = 5.65 / 4.72 - 1 = +19.7% |
Keep value on the BSP before commission. Commission is a cost of betting on the exchange and says nothing new about the runner, so the chance stays at 1 / 5.00 = 20%. If that is right, the bookmaker bet is worth 0.20 x 6.00 - 1 = +20 cents per dollar, and backing at BSP 0.20 x 4.72 - 1 = -5.6 cents. Value betting in horse racing makes the same split before the jump: the net figure says where to bet, the one before commission whether the price was value.
Risk: Betting involves risk. A price that beats BSP can still lose, the exchange sets and can change its commission, and a bookmaker can restrict an account that keeps beating the close. See responsible gambling for limits and support.
Beating the SP: why a bookmaker starting price needs its margin out
A bookmaker's starting price (SP) is a different close. Racing NSW says that at NSW TAB race meetings the official starting price, flucs and top fluc come from the NSW Official Price, built from the larger wagering operators' prices and in use since May 2017 (checked October 2026). At any meeting, NSW included, your bookmaker's terms say which SP settles an SP bet; starting price betting covers the product. An SP drawn from bookmakers' prices can carry their margin, so add 1 / SP across the field before you compare.
Example: Illustrative prices. Your $6.00 runner starts at an SP of $4.20, in an SP market that adds up to 118%. Against the raw SP: 6.00 / 4.20 - 1 = +42.9%. With the margin out: 4.20 x 1.18 = 4.956, and 6.00 / 4.956 - 1 = +21.1%, close to the 20% against a $5.00 BSP.
"I beat the SP by 43%" and "I beat BSP by 20%" can describe the same bet. Use BSP where the race has one, and a margin-free SP where it does not.
Fixed prices at bet time vs BSP over many bets
Only your own record can say whether your early fixed prices beat BSP. Group the bets by when you took the price.
Example: An illustrative record, not real results: 300 win bets of $20 at prices averaging about $6.00. Expected profit at BSP = stake x CLV, summed over the bets: what they would make on average if each BSP were the true chance.
| When the price was taken | Bets | Average CLV against BSP | Bets that beat BSP | Expected profit at BSP | Actual profit |
|---|---|---|---|---|---|
| Day before or race morning | 90 | +6.0% | 58 (64%) | $108 | -$230 |
| 1 to 3 hours before the jump | 110 | +3.0% | 63 (57%) | $66 | +$412 |
| Last 30 minutes | 100 | -0.5% | 41 (41%) | -$10 | -$96 |
| All bets | 300 | +2.7% | 162 (54%) | $164 | +$86 |
For the first row, $20 x 90 x 0.060 = $108. The whole record averages (90 x 6.0 + 110 x 3.0 - 100 x 0.5) / 300 = 2.733%, and $20 x 300 x 0.02733 = $164.
Profit tells a different story: the early bets beat BSP by the most and lost the most money. At prices around $6.00, one standard deviation of profit over 100 bets of $20 is about $20 x square root of (6.00 - 1) x square root of 100 = $447. Luck that size can swing every row, so the CLV column, not profit, is the steadier guide, though every loss is still real money.
Risk: Betting involves risk. An average CLV is evidence about the prices you took, not a forecast, and past results are no guarantee of future results. See responsible gambling for limits and support.
Scratchings, place bets and other edge cases
A late scratching changes the sum for fixed-odds bets struck before it: the race-day stewards declare a cents-in-the-dollar deduction on the successful ones. BR 14 of Racing NSW's Rules of Betting covers NSW on-course bookmakers, betting auditoriums and betting premises. BSP is struck on the smaller field.
Example: Illustrative: you take $8.50 in the morning, a late scratching brings an 11c win deduction, and the BSP is $7.20. On the face-value reading you are paid at 8.50 x (1 - 0.11) = 7.565, a CLV of 7.565 / 7.20 - 1 = +5.1%. If your bookmaker deducts from the winnings only, it pays 1 + 7.50 x 0.89 = 7.675, a CLV of +6.6%. Ignore the deduction and you would log 8.50 / 7.20 - 1 = +18.1%.
Online bookmakers set their own method in their terms, so check which reading yours uses; scratchings and deductions covers the rules. The other cases:
- Place bets: compare with the starting price of the exchange's place market where the race has one, never the win BSP.
- Each way bets: split into win and place halves, with a CLV for each.
- Dead heats: they change the return, not the CLV.
- Bonus bets and boosted prices: keep them in their own group, since the extra value came from the promotion.
The records that make a CLV check possible
| Field | Why the CLV check needs it |
|---|---|
| Date, track, race number and code | Finds the race and its BSP again |
| Runner and saddlecloth number | Names get misspelt; the number does not |
| Bookmaker and bet type | Place halves compare with the place market |
| Price accepted and time taken | The price your bet was struck at, and the time for grouping |
| Stake, and cash or bonus bet | Bonus bets and boosts go in their own group |
| BSP for each market you bet in | The close itself, entered after the race |
| Any deduction declared | Changes the price you are paid |
| Result and profit | Yield beside CLV, for the same bets |
Fill in the BSP for every bet, losers included, or your betting record flatters both columns. A monthly line of bets, average CLV, expected and actual profit shows the trend, and belongs in any betting strategy built on price.
Racing closing lines on B337's Terminal
The Terminal's racing board gives each bookmaker a column, with Betfair back and lay beside them. Each price carries its flucs (price history) and its closing line, the last price before the jump. Prices are read on a repeating cycle, so check a price in your bookmaker account before betting. Terminal View is the first plan that shows Betfair prices and closing lines.
For racing automation, see the horse racing betting bot page on Classic Racing. Close to the jump it sets each bookmaker's win price against the Betfair price on the same runner, and only bets, in your own account, when the expected value clears the threshold you set.
Your computer has to be on, awake, online and running B337 for it to place anything. It needs Full Automation, set up with the team, and bets placed through B337 use credits. Many bookmakers restrict automated betting in their terms. Betfair, TAB and other brand names are trade marks of their owners, and B337 is not affiliated with them.
For free and confidential support call 1800 858 858 or visit gamblinghelponline.org.au.
Risk: Betting involves risk. Automation can bet far more, far faster, than by hand, which makes a deposit limit at every bookmaker worth setting before any session starts. Prices move before bets are accepted, and bookmakers can restrict accounts and void bets. See responsible gambling for limits and support.