The question
"Everyone talks in ticks. What are Betfair tick sizes, and what is one tick actually worth?"
On Betfair you can't back at any price you like. Prices sit on a fixed ladder, and the steps between them change size as the odds get bigger. If you trade, you need to know that ladder by heart.
The idea in one sentence
A tick is one step on Betfair's price ladder, and because the step grows with the price, a one-tick move is worth a different percentage of your stake depending on where you trade.
The picture
Here is the whole ladder. Every valid price from 1.01 to 1000 sits in one of these bands:
| Price range | Tick size | Ticks in the band |
|---|---|---|
| 1.01 to 2 | 0.01 | 99 |
| 2 to 3 | 0.02 | 50 |
| 3 to 4 | 0.05 | 20 |
| 4 to 6 | 0.1 | 20 |
| 6 to 10 | 0.2 | 20 |
| 10 to 20 | 0.5 | 20 |
| 20 to 30 | 1 | 10 |
| 30 to 50 | 2 | 10 |
| 50 to 100 | 5 | 10 |
| 100 to 1000 | 10 | 90 |
That's 350 prices in all. Some distances that surprise people: 2.00 to 3.00 is 50 ticks, but 3.00 to 4.00 is only 20 and 4.0 to 5.0 is 10.
What matters to a trader is what one tick is worth. Green up a £100 back after a one-tick move in your favour (Lesson 8.1) and you lock in:
| Back at | Lay at | Move | Locked on £100 | After 2% commission | Change in implied probability |
|---|---|---|---|---|---|
| 1.51 | 1.50 | 0.67% | £0.67 | £0.65 | 0.44 points |
| 2.02 | 2.00 | 1.00% | £1.00 | £0.98 | 0.50 points |
| 3.05 | 3.00 | 1.67% | £1.67 | £1.63 | 0.55 points |
| 4.1 | 4.0 | 2.50% | £2.50 | £2.45 | 0.61 points |
| 6.2 | 6.0 | 3.33% | £3.33 | £3.27 | 0.54 points |
| 10.5 | 10.0 | 5.00% | £5.00 | £4.90 | 0.48 points |
| 21 | 20 | 5.00% | £5.00 | £4.90 | 0.24 points |
Notice the jumps at the band edges. Just below 2.00, a tick (1.99 to 2.00) is a 0.5% move. Just above, it's 1.0%. Your tick value doubles when you cross 2.00.
| Price | Tick | Implied | 1-tick £ | Move |
|---|---|---|---|---|
| 2.20 | 0.02 | 45.5% | £0.91 | 0.91% |
| 2.18 | 0.02 | 45.9% | £0.92 | 0.92% |
| 2.16 | 0.02 | 46.3% | £0.93 | 0.93% |
| 2.14 | 0.02 | 46.7% | £0.93 | 0.93% |
| 2.12 | 0.02 | 47.2% | £0.94 | 0.94% |
| 2.10 | 0.02 | 47.6% | £0.95 | 0.95% |
| 2.08 | 0.02 | 48.1% | £0.96 | 0.96% |
| 2.06 | 0.02 | 48.5% | £0.97 | 0.97% |
| 2.04stop | 0.02 | 49.0% | £0.98 | 0.98% |
| 2.02 | 0.02 | 49.5% | £0.99 | 0.99% |
| 2.00 | 0.02 | 50.0% | £1.00 | 1.00% |
ticks now 0.01 | ||||
| 1.99target | 0.01 | 50.3% | £0.50 | 0.50% |
| 1.98 | 0.01 | 50.5% | £0.51 | 0.51% |
| 1.97 | 0.01 | 50.8% | £0.51 | 0.51% |
| 1.96 | 0.01 | 51.0% | £0.51 | 0.51% |
| 1.95 | 0.01 | 51.3% | £0.51 | 0.51% |
| 1.94 | 0.01 | 51.5% | £0.52 | 0.52% |
| 1.93 | 0.01 | 51.8% | £0.52 | 0.52% |
| 1.92 | 0.01 | 52.1% | £0.52 | 0.52% |
| 1.91 | 0.01 | 52.4% | £0.52 | 0.52% |
| 1.90 | 0.01 | 52.6% | £0.53 | 0.53% |
Worked Betfair example
You scalp Over 2.5 goals before kick-off, where the price is sitting around 2.00. Your plan: back at 2.02, green up one tick lower at 2.00, and cut the trade if the price goes two ticks against you. Stake £100. (Illustrative figures.)
- The winning trade. Back £100 at 2.02, then lay at 2.00. Lay stake = £100 × 2.02 ÷ 2.00 = £101. Locked profit = £101 − £100 = £1.00, or £0.98 after 2% commission.
- The losing trade. The price drifts two ticks from 2.02 to 2.06. Lay stake = £100 × 2.02 ÷ 2.06 = £98.06. Locked result = £98.06 − £100 = −£1.94. No commission on a loss.
- The break-even win rate. Each win makes £0.98 and each loss costs £1.94. You break even when p × 0.98 = (1 − p) × 1.94, so p = 1.94 ÷ (1.94 + 0.98) = 66.5%.
- Read it. You must win two scalps in every three just to stand still. At 50/50 you lose about 48p a trade on average.
- Move the price. Run the same plan at 4.1/4.0. A win locks £2.50, or £2.45 after commission. A two-tick loss to 4.3 means laying £100 × 4.1 ÷ 4.3 = £95.35, a −£4.65 result. Break-even is 4.65 ÷ (4.65 + 2.45) = 65.5%. The pounds change with the price, but the need to win about two trades in three does not.
Verdict: a tight profit target with a wider stop needs a very high hit rate. Scalping is a real skill, but the ladder maths tells you how good you have to be before you start.
The formula
Ticks between two prices
- Walk from the lower price to the higher one, band by band, dividing the distance in each band by that band's tick size.
In plain English: 1.80 to 2.50 is 0.20 ÷ 0.01 = 20 ticks, plus 0.50 ÷ 0.02 = 25 ticks: 45 in all.
What a tick is worth
- S_b is your back stake.
- O_back is the price you backed at, and O_lay the price you lay at, one or more ticks lower.
In plain English: a tick's value is the percentage move, tick size ÷ price, applied to your stake. The same tick size is worth more at a lower price in the band.
What a tick means in probability
- Δp is the change in implied probability between the two prices.
In plain English: one tick at 2.00 is about half a percentage point of probability. Down at 1.01 to 1.02, one tick is almost a whole point (0.97).
Scalping break-even
- g is the gross profit on a winning trade, ℓ the loss on a losing trade (as a positive number).
- c is commission, 0.02.
In plain English: the bigger your stop compared with your target, the more often you have to be right.
Try it
Set the price to 2.00 and stake £100 and check one tick is worth £1.00 (£0.98 after commission). Then step the price up to 1.99 and see the value halve, and up to 4.0 and see it rise to £2.50.
Common mistakes
- Treating a tick as a fixed amount. A tick at 10.0 moves the price 5%. A tick at 1.50 moves it 0.67%. Size your trades in percentage terms.
- Forgetting the band edges. A stop "5 ticks away" means a different distance either side of 2.00, 3.00 or 4.00.
- Counting ticks when you mean probability. Five ticks at 1.20 and five ticks at 3.00 are very different changes in the chance of the event. Convert to implied probability to compare moves.
- Ignoring the win rate a plan needs. One tick up, two ticks down needs about two wins in three. Know the number before you trade, not after.
- Leaving commission out of small trades. 2% of a £1 green is 2p. It's small, but it applies to every winning trade and moves the break-even win rate.
Speed and execution are real edges, but so is the maths: why good models still lose money.