Machine and Number Games
How to Play Slot Machines
Machine games settled by a random number generator, where the published return decides the cost of playing.
A slot machine settles every spin through a random number generator, a program that produces a continuous stream of numbers without regard to what came before. When the spin button is pressed, the number running at that instant is translated into reel positions. The movement on screen is presentation only; the result was fixed the moment the button was pressed.
Because the player makes no decisions during a spin, the only things under their control are the choice of machine, the stake and the number of spins. This guide explains how to read a pay table, what return to player and volatility mean, and how to work out exposure at the speed machine games run.
How the Machine Decides a Result
The random number generator runs continuously, even while the machine sits idle. Each number maps to a set of reel positions through a fixed table, and that table determines how often each combination appears.
- One result per spin. The outcome cannot be altered after the button is pressed, including by a stop button on the reels.
- No memory. The machine records neither wins nor losses, so no machine is hot or cold.
- Symbol weighting. High-value symbols are given a smaller weighting, which is why large payouts are rare.
- Third-party testing. Machines in regulated jurisdictions are tested by independent laboratories to confirm that results are random and that the return matches the published figure.
Return to Player and House Edge
Return to player is the share of all money staked that comes back to players over the long run. The figure is calculated across millions of spins, not across one session.
| Return | House edge | Cost per 1,000 units staked |
|---|---|---|
| 98% | 2% | 20 |
| 96% | 4% | 40 |
| 94% | 6% | 60 |
| 92% | 8% | 80 |
| 88% | 12% | 120 |
Two percentage points sound small, but a machine runs hundreds of spins an hour. At a stake of 5 units and 600 spins an hour, a 92% machine carries an expected cost of 240 units per hour against roughly 120 for a 96% machine.
Volatility and the Spread of Results
Volatility describes the spread of results rather than the size of the return. Two machines with a 96% return can feel entirely different to play.
| Volatility | Frequency of wins | Size of payouts | Bankroll required |
|---|---|---|---|
| Low | Often, about 25% to 35% of spins | Small, usually under 10 times the stake | Relatively small |
| Medium | Moderate, about 20% to 25% of spins | Moderate, up to 100 times the stake | Moderate |
| High | Rare, about 10% to 20% of spins | Large, sometimes over 1,000 times the stake | Large, with deep swings |
A high-volatility machine needs a larger bankroll to reach the same number of spins, because the runs without a payout last longer.
How a Round of Slot Machines Is Played
A single round of Slot Machines follows the sequence below. The same sequence applies at a physical table and at a live dealer table streamed to a screen.
- Check the published returnOpen the information page and note the return figure. A machine below 94% costs considerably more over the same number of spins.
- Read the pay table and feature conditionsNote the value of the top symbols, the number of pay lines, and what triggers free spins or the top prize.
- Load funds and set limitsDecide the amount to be used and the session loss limit before the first spin, not once the balance has run low.
- Choose the stake per spinThe stake determines hourly exposure. On a progressive machine, check whether the top prize requires a maximum bet.
- SpinPress the spin button. The result is fixed at that moment; the stop button only shortens the animation.
- Check the result against the pay tableWinning combinations are highlighted on screen. Payouts are expressed as a multiple of the stake or in credits.
- Stop at the limit that was setCash out the remaining credit through the collect button or the ticket printer. A machine does not become cheaper for having been played a long time.
Reading a Pay Table
The pay table is the only binding source of information about a machine. It opens from the information button and lists every payout along with the conditions attached to each feature.
- Check the published return. In online games this figure is usually stated on the information page.
- Check the value of the highest symbols, expressed as a multiple of the stake or as credits per line.
- Check the number of pay lines or the ways system, and whether a full stake is required to activate them all.
- Check the feature conditions: how many scatters trigger free spins, how wild symbols substitute, and the maximum payout.
- On progressive machines, check whether the top prize is only available at maximum stake.
Machines that look alike can carry different pay tables in different casinos. Checking the table before playing is the equivalent of checking the table rules at blackjack.
Common Types of Machine
- Three-reel machines
- The oldest format, with few pay lines and a simple pay table. Generally of medium volatility.
- Five-reel video slots
- The most common format, using 10 to 50 pay lines or a ways system with free spin features.
- Megaways and ways machines
- The number of winning paths changes on every spin according to how many symbols land on each reel.
- Progressive machines
- The top prize accumulates from a share of every stake across a network, which lowers the base return.
A progressive machine has an overall return similar to other machines, but most of that return is concentrated in a prize that is hit extremely rarely. Players who want long sessions choose machines without a progressive jackpot.
Spin Speed and Exposure
The largest difference between slots and table games is speed. A single machine can complete six hundred spins an hour, ten times the number of rounds at a baccarat table.
| Stake per spin | Total staked per hour | Expected cost |
|---|---|---|
| 2 | 1,200 | 48 |
| 5 | 3,000 | 120 |
| 10 | 6,000 | 240 |
| 25 | 15,000 | 600 |
Slowing the rate of spins and switching off the autoplay feature is the most direct way to reduce exposure without changing the stake.
Slot Machines Terminology
The terms below are the ones heard most often at the Slot Machines table. A wider list is available in the casino glossary.
- Return to player
- The share of all money staked that comes back to players over the long run, calculated across millions of spins.
- Volatility
- The spread of results on a machine: how often and how heavily it pays.
- Pay line
- A path across the reels that is checked for winning combinations.
- Scatter
- A symbol that pays or triggers a feature without needing to sit on a pay line.
- Wild
- A symbol that substitutes for others to complete a combination.
- Progressive jackpot
- A prize built from a share of every stake across a network of machines.
- Hit frequency
- The share of spins that produce any payout at all, regardless of size.
Slot Machines FAQ
Are there times of day when slot machines pay more often?
No. The random number generator behaves identically at all times and is unaffected by the hour, the day or the number of players. Machines also keep no record of previous results.
Does betting maximum improve the chance of winning?
On most machines, no. A maximum bet simply scales the payouts proportionally. The exception is a machine whose top prize is only available at full stake, and that condition is stated in the pay table.
What does a 96% return mean?
Of every 1,000 units staked over the long run, about 960 come back to players and 40 become operator revenue. The figure does not apply to a single session, which can finish far above or below it.
Does pressing the stop button change the result?
No. The outcome was settled when the spin button was pressed. The stop button only shortens the reel animation.
Why do players avoid a machine that has just paid out?
Because of the belief that it is now empty. The belief has no basis: every spin is calculated separately and the odds do not change after a large payout.
Which machine should a new player choose?
One with a published return of 96% or above and low to medium volatility. That combination gives the greatest number of spins for the same amount of money.