The one-line definition
A bonus buy (also marketed as “feature buy,” “buy bonus,” “buy free spins,” or the ubiquitous “BUY” button in the corner of a slot UI) lets you pay a fixed multiple of your base bet to trigger the bonus round immediately, skipping the base-game grind. The multiple is title-specific and usually sits between 50× and 500× base bet, with 100× being the modal price on modern Pragmatic Play, Push Gaming, Nolimit City, Hacksaw, Relax and BGaming titles.
The two RTPs — the number the button shows and the number it doesn’t
Every buy-feature slot ships two disclosed RTP figures, and they are not the same number:
| RTP figure | What it applies to | Typical value |
|---|---|---|
| Base-game RTP | Every non-buy spin at your base bet | 96.0–96.5% |
| Bonus-buy RTP | The 100× (or whatever multiple) buy itself | 96.5–98.0% |
The buy is almost always a higher-RTP transaction than the base game — usually by 0.5 to 2 percentage points. This is the entire reason the button exists as a marketing device: “buy the feature at 97% RTP” reads like a better deal than “grind the base game at 96% RTP.”
The trap is the word transaction. Base-game RTP applies to a low-cost repeated action (1× stake per spin). Bonus-buy RTP applies to a one-shot event that consumes 100 × stake in a single click. The higher RTP does not compensate for the far higher per-event variance, and it does not compensate for the loss of the small base-game wins that would otherwise offset your entry cost.
The variance math the marketing skips
At €1 base bet, a €100 bonus buy is 100 base spins worth of stake spent as one event. Under the buy’s own RTP, expected loss on that click is €100 × (1 − 0.97) = €3.00 in expectation. That number is honest arithmetic — and completely misleading about your actual bankroll experience.
The bonus round has one of three outcomes, roughly:
- Bust — a bonus that pays back less than the buy (0×–0.5× buy cost). On typical bonus distributions this happens on 35–50% of buys.
- Modest — a bonus that pays 1×–5× buy cost. Roughly 40–50% of buys.
- Hit — a bonus that pays 20×–5,000× buy cost (or the title’s max win, capped at 5,000× to 50,000× base bet). Roughly 3–10% of buys.
The 96.5–98% headline RTP is only visible when you average across all three buckets. In a session of five to ten buys, the observed return is drawn from that outcome distribution, not from the average. Two normal-luck bust buys back-to-back is 200× base bet gone in two clicks — that is not a rare event, and no buy-RTP figure changes it.
The bankroll survival curve
The practical way to think about a bonus-buy budget is: how many buys deep can I go before I hit my bust threshold, and how likely is a “hit” bucket outcome within that buy count?
| Session bankroll | Base bet | Buys available | P(≥ 1 hit-bucket outcome) |
|---|---|---|---|
| €100 | €1 | 1 buy | ≈ 5–10% |
| €500 | €1 | 5 buys | ≈ 25–40% |
| €1,000 | €1 | 10 buys | ≈ 45–65% |
| €500 | €0.50 | 10 buys | ≈ 45–65% |
| €200 | €0.20 | 10 buys | ≈ 45–65% |
Two things are visible from this. First, one buy is a coin toss against the hit distribution — most single buys give you nothing memorable. Second, the same P(hit) can be bought at three different bankroll costs by scaling the base bet down: €200 at €0.20 base bet delivers the same expected exposure as €1,000 at €1. The way most players lose the entire deposit is by keeping the base bet high enough that the deposit only buys 2–3 clicks — always well inside the 35–50% consecutive-bust probability.
For any tracked buy-feature title, the Portfolio Builder will simulate the survival curve on your actual base bet, buy cost, and session budget; the number of buys you can afford at your target hit probability is not something to guess.
Where the “buy is +EV vs grinding” argument holds — and where it lies
The one honest use case for the buy button is: you were going to reach the bonus round anyway, and you’d like to skip the base-game grind. If your session plan is a 400-spin base-game buy-in on a title where the bonus hits roughly once per 300 base spins, you were budgeting for one bonus round and the base-game grind that funds reaching it. Buying that bonus for 100× base bet is arithmetically similar to spinning 300 base rounds at €1 — same expected loss window, less time spent.
The lie inside that argument is the same lie that lies at the core of Martingale-style advice: it only holds if you’d actually have stopped after the bonus. In practice, players who buy the bonus and don’t hit chase the outcome by buying a second and a third. The base-game plan protects itself from that behaviour (running out of spins forces a stop); the buy plan does not (you can always afford one more click). Two consecutive bust buys is the modal experience for a first-time buyer at any modern buy-feature slot, and the third buy is where deposits die.
Regulatory status — the map is not the same as the RTP
Bonus buy is banned in the United Kingdom since October 2021, when the UK Gambling Commission classified it as a feature that “accelerates spend and risks accelerating harm.” Every UKGC-licensed operator removed the button that year — including the UK-licensed instances of Pragmatic Play, Push Gaming, Nolimit City and BGaming titles. The buy button is still present in the exact same titles on the same operators’ non-UK licences (MGA, Curaçao, Anjouan). The mechanic is therefore visible or invisible depending on which licence you land on, not on which slot you open.
The Netherlands (KSA) and Germany (GGL) ban the mechanic as well. MGA (Malta) permits it with a warning label requirement introduced in 2023. Curaçao and Anjouan licences have no restriction, which is why offshore operators serving unregulated markets ship the mechanic universally on every buy-feature title.
Practical consequence for the player: a title’s stated max win cap (e.g. 5,000× stake) and RTP figures may be identical across licences, but only some licences let you take the buy path to that cap. On UKGC operators, the same title can be played only in base-game mode — and its practical volatility is lower, because the buy-only variance path is closed.
Which titles built their reputation on the buy
Bonus buy is now standard, but a handful of titles are the reference implementations that the mechanic is judged against:
- Big Bass Bonanza (Pragmatic Play, 2020) — 100× base bet buy, 10 free spins on the buy. 96.71% RTP. The mass-market title that made the button mainstream.
- Money Train 2 (Relax Gaming, 2020) — 100× base bet buy, up to 50,000× max win. Bonus round is the whole game economy; base game is thin. 96.40% base RTP, 96.20% on the buy (rare inverted case).
- Money Train 3 / Money Train 4 (Relax Gaming, 2021 / 2023) — 100× base bet buy, 100,000× max win. Extended the mechanic with additional buy tiers.
- Fire in the Hole (Nolimit City, 2021) — 200× base bet full buy, xBomb multiplier stacks. 96.06% base, 96.06% buy (identical — Nolimit uses the buy as a variance path, not an RTP path).
- Wanted Dead or a Wild (Hacksaw Gaming, 2022) — 100× base bet buy, three bonus round paths. 96.38% RTP; sharp difference in outcome distribution between the three buy targets.
- San Quentin xWays (Nolimit City, 2021) — 275× base bet buy for the full-feature bonus. Provider tier: max-buy = max-max-win.
- Gates of Olympus (Pragmatic Play, 2021) — 100× base bet buy for the bonus, 96.50% RTP. Popular starting title because base-game grind is playable.
- Sugar Rush (Pragmatic Play, 2022) — 100× base bet buy, cluster-pays cascade. 96.50% RTP.
- Sweet Bonanza (Pragmatic Play, 2019) — 100× base bet buy for guaranteed 4+ scatter entry to the free-spins round. 96.51% RTP.
The pattern across the reference implementations: 100× base bet is the modal price, the buy is usually 0.0–0.5 pp above base RTP (occasionally identical, rarely lower), and the max-win figures are only reachable via the buy path or an equivalent multi-scatter base-game trigger that has roughly the same expected cost.
When the buy is the wrong button
The button is wrong for three specific situations, and it is worth internalising each one:
- Bonus-balance play. Every operator that allows the buy button on real-money play excludes bonus-buy spends from bonus wagering. Buying the feature does not count toward turnover. This is codified in the standard bonus terms — see the reading bonus terms guide for the exact clause language (“game rounds initiated via the buy-feature button do not contribute to wagering”). If you are clearing a deposit-match or free-spins bonus, the buy button is a dead button.
- Sessions shorter than 5 buys of budget. The consecutive-bust probability on modern buys is high enough that a 2–3 buy session is dominated by the bust bucket. If your session budget only affords 2–3 clicks, the base-game grind gives you a more entertaining outcome distribution for the same money.
- Cross-jurisdiction bankroll planning. If you play the same title on both a UKGC operator (buy disabled) and an MGA operator (buy enabled), your realised variance will be dramatically different across sessions on the “same” slot. Plan bankroll to the operator’s licence, not the slot’s max-win cap.
The deposit-bonus interaction the button hides
A subtle failure mode: many players activate a deposit-match bonus, use the bonus balance to fund a bonus buy, and are surprised when the balance disappears with no wagering progress recorded. The mechanism is not a scam — it is a clause. Buy-feature spins are marked in the operator’s back-end as out-of-scope for wagering contribution on the same principle that live-dealer roulette is marked at 10% contribution: the operator sizes its bonus offer around the base-game variance and cannot afford to award turnover credit for the buy path. See the wagering requirements guide for the underlying accounting, and the reading bonus terms guide for the clause you should search for before you fund a buy off a bonus balance.
The CasiMath move
Four rules cover the bonus-buy decision:
- Compare the two RTPs before you click. The buy-RTP is disclosed in the info panel; a buy that is not measurably above the base RTP has no arithmetic case at all.
- Size the base bet to your session budget, not to the slot’s minimum. A €500 bankroll at €0.20 base bet buys 25 clicks; the same bankroll at €1 base bet buys 5. Same slot, five times the chance of reaching the hit bucket.
- Never buy with a bonus balance. The wagering clause almost universally excludes it. If you were going to buy, buy with real-money balance and clear the bonus separately.
- Cap consecutive busts. Two bust buys in a row is the modal experience. A pre-committed cap (“if I bust two, I stop for the session”) is the single behavioural change that separates a losing buyer from a break-even one.
See the buy-feature slots hub for the tracked catalog with base-vs-buy RTP deltas and volatility flags, the volatility guide for the outcome-distribution math the buy inherits, and the Portfolio Builder to simulate any buy-feature title’s survival curve before the first click.