Bonus Maths: Estimating the Real Cost of Clearing Wagering
A headline such as a 200% match says little about whether an offer is favourable. The useful variables are the bonus amount, the wagering requirement, the sum that wagering applies to, the average house edge of eligible games, game-contribution rules, time limits and any maximum-withdrawal condition.
Two long-run estimates give a simplified way to frame the maths:
Estimated theoretical loss = required wagering × house edge
Approximate bonus edge = bonus amount − estimated theoretical loss
The first line estimates the long-run theoretical loss from the stakes needed to clear the offer. The second applies only where wagering is on the bonus alone and no other restrictive terms materially change the result. Both are simplified educational estimates. They do not predict any player's outcome and do not guarantee profit.
Example one: a low multiplier on a bonus-only basis
A player deposits £50 and receives a £50 bonus, with wagering applied to the bonus only at 20x. Required wagering is £50 × 20 = £1,000. Eligible games are assumed to average 98% RTP, so the house edge is 100% − 98% = 2%. Estimated theoretical loss is £1,000 × 2% = £20, and the approximate bonus edge is £50 − £20 = £30, a positive figure under these simplified assumptions.
Example two: a mid-sized bonus that lands near break-even
A £80 deposit attracts a £40 bonus, and the 35x wagering is calculated on the bonus only. Required wagering is £40 × 35 = £1,400. With an average RTP of 97%, the house edge is 100% − 97% = 3%. Estimated theoretical loss is £1,400 × 3% = £42, leaving an approximate bonus edge of £40 − £42 = −£2, which is close to break-even.
Example three: wagering on deposit plus bonus
Here a £100 deposit is matched with a £100 bonus, and the 40x requirement applies to deposit plus bonus, giving a wagering base of £200. Required wagering is £200 × 40 = £8,000. At an average RTP of 96%, the house edge is 100% − 96% = 4%, so estimated theoretical loss is £8,000 × 4% = £320. The approximate bonus edge is £100 − £320 = −£220. Because wagering is not on the bonus alone, this figure is only a rough indicator, but it shows how a larger wagering base pushes the estimate below zero.
The model becomes less reliable in several cases: games contributing below 100% demand more stakes, RTP that varies between eligible titles makes one average misleading, a maximum cashout can cap any gain, wagering on deposit plus bonus raises turnover, and a time limit may end the offer before wagering is done. A bonus or balance held in a volatile cryptoasset can change in GBP value between crediting, wagering and withdrawal; stablecoins limit price movement but do not replace reading the terms. RTP is a long-run statistical average, so short sessions can produce very different results.