Feature frequency
Feature frequency is how often, on average, a slot's bonus feature triggers, usually written as "1 in 200 spins" or similar. It is an average over a huge number of spins, not a countdown, so you might hit the feature twice in ten spins or wait 600. Knowing the figure lets you work out what reaching the feature is likely to cost.
By the Best Slots UK team. Last checked .
Key takeaways
- Feature frequency is an average trigger rate, such as one free spins round per 200 spins.
- At 50p a spin, a 1 in 200 feature costs about £100 of stakes to reach on average.
- With a 1 in 200 feature, roughly one session in twelve of 500 spins will see no trigger at all.
- Rarer features usually pay more when they land, which is a big part of volatility.
- Written as
- 1 in X spins
- Type
- Long-run average
- Where shown
- Help screen, if published
- Not the same as
- Hit frequency
- Bonus buy in GB
- Not offered
What feature frequency means
Every slot with a bonus round has a designed probability of triggering it on any given paid spin. Expressed as "1 in X", that probability is the feature frequency. A free spins round with a 1 in 200 frequency has a 0.5% chance of starting on each spin, and the chance is the same on every spin regardless of what happened before.
It is different from hit frequency, which counts any winning spin, however small. A game can hit one spin in three yet trigger its main feature only one spin in 300. Some games have several features with their own frequencies, such as a common respin and a rare top bonus.
What a feature costs to reach at UK stakes
Since bonus buy is not offered in Great Britain, the only way into a feature is through base game spins. The average amount you stake before a trigger is simply the frequency multiplied by your stake. Base-game wins return some of that along the way, but the stake you put through is the figure to compare with your budget.
| Feature frequency | Average stakes to trigger at 50p | Chance of no trigger in 500 spins |
|---|---|---|
| 1 in 100 | £50 | Under 1% |
| 1 in 150 | £75 | About 3.5% |
| 1 in 200 | £100 | About 8% |
| 1 in 250 | £125 | About 13.5% |
| 1 in 400 | £200 | About 29% |
Five hundred spins at the UK minimum of 2.5 seconds each takes at least 20 minutes and, at 50p, puts £250 through the game. On a 1 in 400 feature, more than a quarter of such sessions will end without seeing it at all. That is not bad luck; it is what the number means.
Why a feature is never "due"
Because each spin is independent, the wait for a feature follows a long-tailed pattern: many triggers come quickly, a few take a very long time. For a 1 in 200 feature:
- Half of all waits end within about 139 spins.
- Nine in ten end within about 460 spins.
- One in ten waits runs longer than 460 spins, and some go well past 1,000.
The average of 200 is pulled up by those long waits. After 300 dry spins, the chance of triggering on the next spin is still exactly 1 in 200, which is why the belief that a game is building up to a bonus is a myth. Our guide on why slots are never due a win covers this in depth, and the RNG entry explains the mechanics.
Feature frequency, feature size and volatility
Frequency and average payout are linked. If features supply a given share of a game's RTP, the rarer they are, the more each one must pay on average. A quick way to estimate it: average feature win ≈ (share of RTP from features) × (1 in X).
| Feature frequency | Average feature win | At 50p stake |
|---|---|---|
| 1 in 100 | About 40× stake | About £20 |
| 1 in 200 | About 80× stake | About £40 |
| 1 in 400 | About 160× stake | About £80 |
Those are averages, and the typical feature pays less than the average because a few very large rounds pull it up. This trade-off between how often and how much is the heart of volatility. It is also why a feature-heavy game can drain a budget between triggers, as the base game entry shows.
The 40-point share is made up to show the arithmetic. Studios rarely publish the split between base game and features.
Where to find a slot's feature frequency
Some studios print the bonus trigger rate in the game's help screen, sometimes next to the RTP or the max win probability. Many don't publish it at all. If it isn't listed, avoid figures quoted on forums or in streams, which are usually based on a small and unrepresentative sample. Our guide to reading a slot's game info screen shows where to look, and how slot features trigger explains the different trigger types, from scatters to random awards.
Related terms
Feature frequency connects to the free spins feature, the most common thing it measures; to retrigger, which is a feature landing again inside itself; and to scatter symbols, the usual trigger.
18+. Gambling should be entertainment that costs money, not a way to make it. Set a deposit limit before you play: how to set limits. Free, confidential help: National Gambling Helpline 0808 8020 133.
Frequently asked questions
What is feature frequency on a slot?
Feature frequency is the average rate at which a slot's bonus feature triggers, usually written as 1 in X spins. A 1 in 200 figure means a 0.5% chance of triggering on any paid spin. It is a long-run average, so actual waits vary widely; some features land within a few spins and others take many hundreds. Where a studio publishes it, you'll find it in the game's help screen. Our guide on how slot features trigger explains the mechanics.
How many spins does it take to trigger free spins?
On average, the number in the game's feature frequency, but any single wait can be much shorter or longer. For a 1 in 200 feature, half of waits end within about 139 spins and nine in ten within about 460. Around one session in twelve of 500 spins will see no trigger at all. Many studios don't publish the figure, so plan your budget on the assumption that the feature might not arrive. See how long £100 lasts on slots for budgeting maths.
Is feature frequency the same as hit frequency?
No. Hit frequency counts every winning spin, including wins smaller than your stake, while feature frequency counts only triggers of a bonus round. A slot can have a hit frequency of one in three and a feature frequency of one in 250. Both figures matter: hit frequency tells you how often the balance moves up, and feature frequency tells you how often the bigger events arrive. The hit frequency entry explains its side of the picture.
Does a slot become more likely to trigger the feature after a long wait?
No, the chance is identical on every spin. Each result comes from an independent random number, so 300 dry spins leave the next spin with exactly the same odds as the first. Long waits feel like they must end soon, but that feeling is the gambler's fallacy. Raising your stake because a feature seems due only increases how much you lose if it doesn't land. Our page on whether slots get hot or cold explains why.
Why can't I buy the feature on UK slots?
Bonus buy is not offered to players in Great Britain. Elsewhere, buying a feature commonly costs 100 times the stake or more in a single purchase, which turns a long wait into one large bet. On UK versions of games the button is simply absent, so the only way into a feature is through normal base-game spins at your chosen stake, each taking at least 2.5 seconds. The how bonus buys work guide covers the mechanics and the UK position.
Are slots with frequent features better?
Not necessarily better, just different. Frequent features usually pay less each time, while rare ones pay more on average when they land; the overall RTP may be identical. Games with frequent features tend to feel steadier and suit smaller budgets, while rare-feature games swing harder and can leave you without a trigger for a whole session. Pick the pattern that suits your budget and patience. Our list of best slots with free spins features groups games by style.
Do free spins from a casino offer count towards triggering a feature?
Yes, promotional spins are ordinary spins on the game at a fixed stake, so each one has the normal chance of triggering the slot's bonus round. With 80 promotional spins on a 1 in 200 feature, the chance of at least one trigger is about 33%. Most of the time, then, promotional spins play out in the base game. The free spins (bonus) entry explains how those offers are structured.