Matched betting calculator

Picking the wrong one is the most common way people end up unbalanced, so it is worth being precise about the difference. All three ask for the same four inputs. What changes is what the bookmaker gives back when the bet wins.

Qualifying bet. A normal bet placed with your own money to trigger a promotion. If it wins, the bookmaker returns your stake plus the profit, but the stake was already yours, so only the profit is a gain. If it loses, you lose real cash at the bookmaker and the exchange pays you. Balanced correctly, both outcomes land on the same small loss: the qualifying loss.

Bonus bet, stake not returned. The standard Australian bonus bet. If it wins, the bookmaker pays the profit and keeps the bonus stake, so a $50 bonus at 4.00 pays $150 rather than $200. If it loses, you lose nothing of your own at the bookmaker, because the stake was never your cash. That asymmetry is why the lay stake formula drops the stake portion out.

Bonus bet, stake returned. Rarer, and worth much more. The bookmaker pays the profit and gives the stake back, so it behaves like free cash and uses the same lay stake as a qualifying bet. If a promotion says the bonus is returned with winnings, use this mode.

Commission is the part most explanations get vague about. An exchange only takes commission on a net win, so a lay bet at odds of 4.20 with five percent commission behaves exactly like a lay bet at 4.15. That is why the commission rate, expressed as a decimal, is subtracted from the lay odds in the denominator.

The commission rate is a decimal fraction, so five percent is 0.05 and the denominator for lay odds of 4.20 is 4.15. Enter the percentage in the calculator above and it does the conversion for you.

A promotion requires a $50 bet. You back a selection at 4.00 with the bookmaker, and the same selection is available to lay at 4.20 on the exchange. Your commission rate is five percent.

• Lay stake: (4.00 x 50) divided by (4.20 - 0.05), which is 200 divided by 4.15, which is $48.19.
• Liability: the unrounded lay stake of 48.1928 multiplied by 3.20, which is $154.22. That is the amount the exchange holds until the market settles.
• If the back bet wins: the bookmaker pays $150 profit and you lose the $154.22 liability, so you are down $4.22.
• If the lay bet wins: the exchange pays $48.19 less five percent commission, which is $45.78, and you lose the $50 staked at the bookmaker, so you are down $4.22.

Both outcomes land on the same $4.22. That is the check: a lay stake is correct precisely when the two sides agree. The $4.22 is what it cost you to unlock the promotion, and the promotion is where the value is.

The qualifying bet above triggered a $50 bonus bet, stake not returned. You back at 4.00 and lay at 4.20 again, still on five percent commission.

• Lay stake: ((4.00 - 1) x 50) divided by 4.15, which is 150 divided by 4.15, which is $36.14.
• Liability: the unrounded lay stake of 36.1446 multiplied by 3.20, which is $115.66.
• If the back bet wins: the bookmaker pays $150 and keeps the bonus stake, and you lose the $115.66 liability, leaving $34.34.
• If the lay bet wins: the exchange pays $36.14 less commission, which is $34.34, and nothing of your own is lost at the bookmaker.

Both sides land on $34.34, which is 68.7 percent of the $50 face value. Longer odds convert a larger share of a bonus bet, which is why bonus bets are usually placed at longer prices, and why they tie up more liability while they run. The bonus bet calculator is this same engine preset to that bet type.