Forecast and Tricast Calculator
Work out a straight, reverse or combination forecast, or a straight or combination tricast: how many bets the slip contains, what it costs, what it returns on the declared CSF or tricast dividend, and the dividend it needs to break even. Enter the win odds and the calculator also estimates how likely the bet is to land.
Uses the first 2 selections in the order listed: Horse A, then Horse B.
Result
- Number of bets
- 1
- Total stake
- £1.00
- Break-even dividend
- £1.00
Estimated from the win odds
- Chance the bet lands
- 10.0%
- Average dividend needed long run
- £10.00
How Forecasts and Tricasts Are Settled
A straight forecast picks the first and second in the correct order. A reverse forecast (also called a dual forecast) is two straight forecasts on the same pair, one in each order, so it costs twice the unit stake. A combination forecast covers every order for any two of three or more selections: n × (n − 1) bets. Tricasts work the same way for the first three places: a straight tricast is one bet, and a combination tricast is n × (n − 1) × (n − 2) bets.
UK bookmakers do not quote a price for these bets in advance. They pay a dividend declared after the race: the Computer Straight Forecast (CSF) for forecasts and the tricast dividend for tricasts, both calculated from the starting prices of the horses involved and the size of the field, and both quoted per £1 including the stake. Because only one finishing order can happen, at most one line on the slip wins. That is why the break-even dividend is simply the number of bets: a 24-bet combination tricast at £1 a line costs £24, and needs a dividend above £24 to show a profit.
| Selections | Combination forecast | Combination tricast |
|---|---|---|
| 2 | 2 bets (reverse) | — |
| 3 | 6 bets | 6 bets |
| 4 | 12 bets | 24 bets |
| 5 | 20 bets | 60 bets |
| 6 | 30 bets | 120 bets |
| 7 | 42 bets | 210 bets |
| 8 | 56 bets | 336 bets |
Worked Example: Three Horses at 2/1, 4/1 and 6/1
Take three runners at decimal odds of 3.00, 5.00 and 7.00 (2/1, 4/1 and 6/1), with implied chances of 33.3%, 20.0% and 14.3%. The Harville model estimates the chance of each finishing order from those win chances: horse A wins (33.3%), then horse B takes second from what is left (20.0% ÷ 66.7% = 30.0%), so A then B comes out at 10.0%.
| Bet (£1 a line) | Bets | Chance it lands | Average dividend needed |
|---|---|---|---|
| Straight forecast A–B | 1 | 10.0% | £10.00 |
| Reverse forecast A/B | 2 | 18.3% | £10.91 |
| Combination forecast A, B, C | 6 | 37.9% | £15.82 |
| Straight tricast A–B–C | 1 | 3.1% | £32.67 |
| Combination tricast A, B, C | 6 | 14.0% | £42.97 |
The last column is the number of bets divided by the chance of landing: the average dividend the slip would need, over many races, just to get its money back. Covering more orders raises the chance of a return but raises the bar the dividend has to clear. The estimate keeps the bookmaker's margin that sits in the win odds, and Harville is known to overrate favourites for second and third, so read these figures as the size of dividend to expect, not a fair price.
Related Calculators
Selections in different races are combined with multiples rather than forecasts. The doubles and trebles calculator settles every pair and trio, and the round robin calculator adds the up-and-down singles.
If you want a return when your horse finishes in the places rather than in an exact order, the each-way calculator works out the win and place parts. When horses tie for a place, the dead heat calculator shows how the stake is split, and a late withdrawal brings in the Rule 4 calculator.
Fractional prices go in as decimals: the odds converter does it in one step. The settlement rules for each-way terms, non-runners and dead heats are in our horse racing betting rules guide.
Frequently Asked Questions
What is a CSF dividend?
CSF stands for Computer Straight Forecast. It is the dividend UK bookmakers pay on a forecast in a horse race, calculated by a formula from the starting prices of the runners involved and the size of the field rather than set in advance. It is declared per £1 stake and includes the stake, so a CSF of £23.45 returns £23.45 to a £1 straight forecast and half that to a 50p one. Tricasts are settled the same way, on a declared tricast dividend.
How many bets is a combination tricast?
A combination tricast covers every order in which your selections could fill the first three places, so it is n × (n − 1) × (n − 2) bets: 6 with three selections, 24 with four, 60 with five and 120 with six. A combination forecast covers every order for the first two places, n × (n − 1) bets: 6 with three selections, 12 with four and 20 with five. Only one line can win, so the dividend has to beat the number of bets for the slip to show a profit.
Is a forecast the same as a tote exacta?
The bet is the same, first and second in the correct order, but the payout works differently. A bookmaker forecast pays the CSF, worked out from the starting prices. A tote exacta pays a share of a pool: all the money staked on the exacta, less the operator's deduction, divided among the winning tickets. The two dividends on the same race can differ a lot, in either direction, so compare the declared results rather than assuming one is always better. The same applies to the tricast and the tote trifecta.
What happens to a forecast or tricast if one of my selections does not run?
The rule depends on the bookmaker. A common approach is that a straight forecast with a non-runner becomes a win single on the remaining selection, and that combination bets are reduced to the lines that no longer include the non-runner. Some firms also only accept tricasts on races with a minimum number of runners. Read the forecast and tricast section of your bookmaker's racing rules before you place the bet.
How accurate is the estimated chance of the bet landing?
It is an estimate from the Harville model, which turns win odds into the chance of a given finishing order: the winner's probability, then the second's share of what is left, then the third's. It is quick and widely used, but it tends to overrate favourites for the minor places, and the bookmaker's margin is left in the prices you enter. Treat it as a guide to the size of the dividend a bet needs, not as a fair price.
Combination forecasts and tricasts put many bets on one slip, and only one line can win. Decide the full cost before you place the bet and never chase losses. 18+. If gambling stops being fun, see our responsible gambling resources.