KEY TAKEAWAYS
The real value of a casino bonus is the bonus amount minus the average cost of meeting its wagering requirement. That cost is the total amount that must be wagered multiplied by the house edge of the games being played. A $100 bonus with a 30x requirement on a game with a 4% house edge needs $3,000 in wagers, which costs about $120 on average. The simplified value is therefore about −$20, not +$100.
This is the central point of bonus math: a bigger headline does not mean a bigger value. The multiplier, the rollover base, the contribution rate and the caps decide what an offer is worth, and they can turn a large bonus into a negative one.
This guide shows the formulas, works through fictional examples, compares two offers and explains the limits of the estimate. Every offer is hypothetical, and no real casino is described. Terms vary between offers and states, so the offer’s own terms are what count.
How the Value of a Bonus Is Worked Out
A deposit match bonus, as described in how a casino deposit match bonus works, adds funds that usually cannot be withdrawn until a wagering requirement is met. Wagering means placing bets, and on standard casino games each bet has a negative expected value for the player. The longer the requirement, the larger the expected cost of clearing it.
The estimate works in three steps. First, count the required wagering from the multiplier and the rollover base, as explained in how wagering requirements work. Second, convert it to actual bets using the game’s contribution rate. Third, multiply the bets by the house edge, which is 100% minus the return to player (RTP).
The result is an average, not a forecast. Over a few hundred bets, a player can finish well ahead or well behind it. That spread is variance, and it is not evidence that a bonus works or does not. A short run of luck changes the final balance, not the expected cost.
Other terms can limit the value further. A maximum cashout cap can stop a good result from being withdrawn, a maximum bet rule can slow the process, and an expiry date can end it early. These are covered in bonus terms and conditions.
The Formulas and Their Assumptions
The first formula gives the wagering a bonus requires.
where:
multiplier = the x in the terms, such as 30x; base = the bonus only (B) or the deposit plus the bonus (D + B), as the terms state.
The second formula gives the cost and the simplified value.
where:
actual bets = required wagering ÷ contribution rate (100% counts as 1.00); house edge = 100% − RTP; bonus = the bonus credited.
The third gives the break-even point for a bonus-only requirement at 100% contribution.
where:
house edge = the edge of the game being played, written as a decimal, such as 0.04 for 4%.
These are simplified estimates. They ignore caps, maximum-bet rules, time limits, variance and the chance of losing the whole balance before the requirement is finished. The examples use a hypothetical slot with a 96% RTP, a 4% house edge, and 100% contribution unless stated.
Worked Examples: Fictional Offers Compared
Example offer (fictional): Casino A offers a 100% match up to $200 with a 30x requirement on the bonus only. A $100 deposit earns a $100 bonus.
Step 1. Required wagering = 30 × $100 = $3,000.
Step 2. Expected cost = $3,000 × 4% = $120.
Step 3. Simplified value ≈ $100 − $120 = −$20.
Now suppose the same bonus had a 20x requirement: $2,000 × 4% = $80, so the value is about +$20. If the 30x applied to deposit plus bonus instead, the wagering would be 30 × $200 = $6,000, the cost $240, and the value about −$140.
Comparison (fictional): Casino X offers a 100% match up to $500 with 40x on the bonus only. Casino Y offers a 100% match up to $100 with 20x on the bonus only. Each player deposits the maximum.
Casino X: the bonus is $500, the wagering is 40 × $500 = $20,000, the cost is $20,000 × 4% = $800, and the value is about $500 − $800 = −$300.
Casino Y: the bonus is $100, the wagering is 20 × $100 = $2,000, the cost is $2,000 × 4% = $80, and the value is about $100 − $80 = +$20.
In words: the smaller bonus is worth more. On average, Casino X costs $300 more than its bonus returns, while Casino Y comes out about $20 ahead. Neither is a promise for one session, and Casino X also involves a $500 deposit against $100 for Casino Y, five times as much money in play.
Two limits sit on top of these figures. Wagering $20,000 takes many bets, so the chance of losing the whole balance before the requirement is finished is far higher for Casino X than for Casino Y, and a maximum bet rule can lengthen the process further. Any cashout cap would also cut a good result back to the cap. The estimate therefore describes the average cost of the terms, not what any one player should expect to see in a single session.
Variations: Multipliers, Games and Contribution Rates
The table shows a fictional $100 bonus with a bonus-only requirement at a 4% house edge and 100% contribution.
| Multiplier | Required wagering | Expected cost at 4% | Simplified value |
|---|---|---|---|
| 10x | $1,000 | $40 | +$60 |
| 20x | $2,000 | $80 | +$20 |
| 25x | $2,500 | $100 | $0 |
| 30x | $3,000 | $120 | −$20 |
| 40x | $4,000 | $160 | −$60 |
The break-even multiplier is 1 ÷ 0.04 = 25x, which matches the table. A lower house edge raises it. On European roulette, with a 2.70% edge, 30x on a $100 bonus costs $3,000 × 2.70% = $81, so the value is about +$19, if the game is allowed to count. Many offers exclude such games or count them at a reduced rate.
Contribution rates matter. If a game contributes only 10%, then $3,000 of required wagering needs $3,000 ÷ 0.10 = $30,000 in actual bets. At a 2.70% edge, that costs $30,000 × 2.70% = $810, so the value is about −$710. A game that contributes 0% never clears the requirement. The same logic applies to a sportsbook boost, as shown in how odds boosts work.
Common Catches and Mistakes
Reading the bonus as profit is the most common mistake. The bonus is an upper limit on value, and the cost of clearing it is subtracted before anything is left.
Ignoring the rollover base can double the cost. A 30x on deposit plus bonus is twice a 30x on the bonus alone when the match is 100%.
Using the wrong house edge changes every answer. A figure should come from a stated RTP or a reliable source, not from memory.
Forgetting the caps overstates the value. A value can never exceed a maximum cashout cap, so any estimate above the cap is cut to it.
Treating the estimate as a prediction misreads an average. A result can differ widely from it in either direction.
Finally, a bonus is never a reason to deposit or bet more than planned. Gambling is best treated as paid entertainment within a budget.
Checklist: Working Out a Bonus Value
Before deciding anything, write the offer’s terms down and work through these points:
- The bonus amount, after any cap on the match
- The multiplier and the rollover base
- The contribution rate of the game to be played
- The house edge or RTP of that game, stated as an assumption
- The maximum bet, the expiry and any cashout cap
- The expected cost: actual bets × house edge
- The simplified value: bonus − expected cost
To check the work, recompute each figure a second way and confirm that the value never exceeds the cap.
Related Concepts and Next Steps
Value follows from the rollover, so how wagering requirements work is the natural companion to this guide, and the other conditions that cap or shorten a bonus are covered in bonus terms and conditions.
For poker promotions the measure of effort is rake, not wagering, and sportsbook promotions are valued by odds. Terms vary by offer, so the offer’s own terms are what count.
Frequently Asked Questions