Bonus Frequency Bonus Frequency
A value showing how many spins, on average, it takes for a bonus feature like free spins to trigger once. "1/150" means once every 150 spins on average, and it matters for understanding volatility and bonus buy prices.
| English | Bonus Frequency |
|---|---|
| Classification | Math & Probability |
| English | Bonus Frequency |
| Category | Math · Probability |
| Notation | 1/N (once every N spins on average) |
| Typical range | Roughly 1/100 to 1/500 (varies by game) |
| Related | Hit frequency, bonus buy, ante bet |
| Note | It is only an average; a bonus is not guaranteed within N spins |
Overview
Bonus frequency is the average number of spins it takes for a bonus feature such as free spins to trigger once. It is usually written like “1/150,” which means you enter the bonus once every 150 spins on average.
This is a different value from the hit frequency, which shows how often regular wins occur. Even with a high hit frequency, bonuses can be rare.
An average is not a “guarantee”
A bonus frequency of 1/150 is only an average. It doesn’t mean the bonus is guaranteed within 150 spins. If each spin independently has a 1/150 bonus chance, it looks like this:
| Spin count | Chance of never getting a bonus |
|---|---|
| 150 spins | About 36.7% |
| 300 spins | About 13.5% |
| 450 spins | About 5.0% |
| 600 spins | About 1.8% |
Even with an average of 150 spins, about one in three players won’t see the bonus within 150 spins. And going 300 spins without one doesn’t make the next spin any more likely to trigger it (gambler’s fallacy).
Bonus frequency and volatility
| Type | Bonus Frequency | Bonus size |
|---|---|---|
| Low volatility | Frequent (e.g., 1/100) | Small |
| High volatility | Rare (e.g., 1/300 or higher) | Large, with wide spread |
In most high-volatility slots, a large share of the RTP comes from the bonus. That’s why in games with rare bonuses, the stretches of losing in the base game can feel long (volatility).
Relationship with the bonus buy price
The bonus buy price is generally set based on “average bonus value ÷ the game’s RTP ratio.” For example, if the average bonus value is 96x the bet and the purchase price is 100x, the RTP of the buy feature is 96%. Games with a lower bonus frequency tend to have higher buy prices.
Buying a bonus skips the base game, but its expected value is designed to be similar to regular play. However, a large amount is at stake at once, so the spread of results becomes much wider.
Relationship with ante bets
An ante bet is a feature that raises bonus frequency in exchange for paying a bit more per bet. For example, you pay 25% more and the bonus chance doubles. Even then, the overall RTP is designed to stay almost the same, so the bonus comes more often but the cost per spin goes up.
Where to check
Providers often don’t disclose bonus frequency. Some games list “average 1 in N spins” on the game rules (i) screen or in provider materials, and review sites sometimes estimate it by recording many spins. However, recorded estimates can differ greatly from the real value if the sample is small (law of large numbers).