Betfair commission is a fee taken from your winnings, never your stake, when a market settles. In Australia the rate is 6% on sport and international racing, 10% on NRL, and 8% or 10% on Australian racing depending on the state and code, according to Betfair's own commission page. That means the price you see on the exchange is not the price you get. At 8%, a back price of $3.00 really pays like $2.84.
The rest of this guide shows how to turn any exchange price into its real price, how commission works when you lay, why it is charged on the whole market, and how to tell whether an exchange price actually beats a bookmaker's fixed odds. Every number below is invented to show the maths. None of it is a tip.
The Betfair commission rates in Australia
Betfair calls its rate the Market Base Rate (MBR). It is the most you pay as a share of your winnings, and each market lists its rate in its rules. Betfair says the rates differ because they reflect "the product fees each racing and sporting body charges".
| Market | Market Base Rate |
|---|---|
| Sport (except NRL) | 6% |
| International racing | 6% |
| NRL | 10% |
| Australian racing | 8% or 10%, by state and code |
| NSW and ACT racing | 10% |
Source: Betfair Hub for the current rates, and The Straight for NSW and ACT.
These rates went up in March 2025. Australian racing outside NSW and ACT rose from 7% to 8%, and sport and non-Australian racing rose from 5% to 6%. NSW and ACT racing and the NRL stayed at 10%. The Straight reported that the rise followed higher point of consumption tax (Victoria's went from 10% to 15% on 1 July 2024) and higher compliance costs. If a guide you are reading still says Betfair charges 5%, it is out of date.
Betfair also notes that "some customers may incur other types of charges through extremely high activity". Most bettors will never see them, but the same page links to the details.
How Betfair works out commission
Betfair's own example uses the Melbourne Cup, which is Victorian thoroughbred racing at 8%:
- You back a horse for $50 at $3.00 and it wins.
- Your return is $150, so your winnings are $150 minus the $50 stake, which is $100.
- Commission is $100 × 8% = $8.00.
- You collect $142 instead of $150.
That $8 is why exchange prices can't be compared with bookmaker prices as they appear. A $3.00 exchange price that pays $142 on a $50 bet is really a price of $2.84.
The real price after commission
Here is the formula to turn any exchange back price into its real price:
Real price = 1 + (exchange price minus 1) × (1 minus commission rate)
So at 8%, $3.00 becomes 1 + 2 × 0.92 = $2.84. At 10%, it becomes 1 + 2 × 0.90 = $2.80.
The higher the price, the more commission takes off it, because it only comes out of the profit:
| Exchange price | At 6% | At 8% | At 10% |
|---|---|---|---|
| $2.00 | $1.94 | $1.92 | $1.90 |
| $3.00 | $2.88 | $2.84 | $2.80 |
| $5.00 | $4.76 | $4.68 | $4.60 |
| $11.00 | $10.40 | $10.20 | $10.00 |
| $21.00 | $19.80 | $19.40 | $19.00 |
The real price is also the one to use for implied probability. A real price of $2.84 implies 1 ÷ 2.84 = 35.2%, not the 33.3% the $3.00 headline suggests. If you are adding up a market to find its market percentage or working out fair odds, the headline exchange prices will make the market look cheaper than it is.
Does an exchange price beat a bookmaker's fixed odds?
This is the question that matters on a Spring Carnival Saturday. Say the same runner shows:
| Where | Price shown | Real price on a winning bet |
|---|---|---|
| Bookmaker (fixed odds) | $2.90 | $2.90 |
| Exchange at 8% | $3.05 | $2.89 |
The exchange looks better, but it isn't. On a $50 bet:
- Bookmaker: $50 at $2.90 returns $145, a profit of $95.
- Exchange: $50 at $3.05 is a profit of $102.50, less 8% commission ($8.20), which leaves $94.30.
The break-even exchange price
To beat a fixed price, the exchange needs to be at least:
Break-even exchange price = 1 + (fixed price minus 1) ÷ (1 minus commission rate)
| Fixed price | Exchange needs at 8% | Exchange needs at 10% |
|---|---|---|
| $2.90 | $3.07 | $3.11 |
| $5.00 | $5.35 | $5.45 |
| $11.00 | $11.87 | $12.11 |
So a runner at $5.00 with a bookmaker needs about $5.35 on an 8% exchange market before the exchange pays more. In a NSW race at 10% it needs about $5.45. BetBank's racing odds screen shows the best fixed price across Australian bookmakers, which is the number to run this check against.
Commission on lay bets
On an exchange you can also lay: bet that a runner won't win. When you lay, you accept the backer's stake and pay out if the runner wins. Wikipedia's page on betting exchanges describes this as taking the other side of a back bet.
Commission comes out of what you win as a layer too. Lay $100 at $3.00 in an 8% market:
- Your liability (what you pay if the runner wins): $100 × (3.00 minus 1) = $200.
- If the runner loses, you keep the $100 stake less 8% commission: $92.
So you are risking $200 to win $92. Commission makes a lay price work like a higher one:
Real lay price = 1 + (lay price minus 1) ÷ (1 minus commission rate)
At 8%, laying at $3.00 is really like laying at 1 + 2 ÷ 0.92 = $3.17.
This is the maths behind the lay side of every matched bet and bonus bet conversion. Our guide to matched betting in Australia works through full examples, and the bonus bet converter sizes the lay stake for you.
Commission is charged on the whole market
Exchanges charge commission on your net winnings in each market, and nothing when you lose overall, as Wikipedia's betting exchange entry explains. That changes the maths when you have more than one bet in the same race.
Say you back two runners in one win market at 8%:
- Runner A: $20 at $4.00
- Runner B: $20 at $6.00
| Result | Bet A | Bet B | Net in the market | Commission at 8% | You keep |
|---|---|---|---|---|---|
| A wins | +$60 | minus $20 | +$40 | $3.20 | +$36.80 |
| B wins | minus $20 | +$100 | +$80 | $6.40 | +$73.60 |
| Neither wins | minus $20 | minus $20 | minus $40 | $0 | minus $40 |
If A wins, commission is 8% of the $40 net, not 8% of A's $60. If the win and place are separate markets, each one is netted on its own, so a loss in one doesn't reduce commission in the other. The exact rate for each market is in its rules.
A quick checklist before you bet on an exchange
- Check the market's rate: 6%, 8% or 10% makes a real difference on longer prices.
- Convert to the real price: 1 + (price minus 1) × (1 minus rate).
- Compare with the best fixed price: use the break-even formula, not the headline numbers.
- Use real prices for any maths: implied probability, market percentage and expected value all need the after-commission price.
- For lays, size the liability first: know what you pay if the runner wins before you place it.
- Set a limit: decide your stake before the day starts and stick to it.
Compare the Spring Carnival prices first
The Cox Plate is on Saturday 24 October and the Melbourne Cup on Tuesday 3 November, both at Flemington, per Racing Victoria's spring program. Before you weigh up an exchange price for either, see the best fixed odds for every runner on BetBank's racing odds screen, then run the break-even check above. The odds calculators cover implied probability and no-vig fair odds if you want to go further.
18+ only. Betting carries real risk of loss, and no price or tool makes a bet a winner, so set limits and gamble responsibly. If you want a break from online betting, BetStop is the free national self-exclusion register.