Part of the complete guide: Provably fair: the complete guide
The two main machine types
In both, each ball is selected without anyone touching it during the draw. The results appear in the order the balls are drawn, then are recorded, verified and published.
| Type | How it works | Typical use |
|---|---|---|
| Gravity-pick | Balls are mixed in a drum; a ball falls or is gently drawn through a chute when the machine releases it | Many national lotteries |
| Air-mix | Jets of air blow balls around a chamber; a ball is drawn by suction or a gate | Many large jackpot games |
How the balls are controlled
Large multi-state games are drawn in studios operated by a state lottery: for example, Powerball is drawn in a studio in Florida and Mega Millions in one in Georgia, at the time of writing.
- Balls are weighed and measured, and replaced regularly.
- Several sets of balls and several machines are kept, and which are used for a given draw is chosen at random at the last moment.
- The equipment is stored in secure rooms, with access logged.
- Independent auditors watch the draw and check the equipment before and after.
- Most draws are recorded and broadcast or posted online.
Random number generators
Many lotteries use computer-based random number generators for some games, such as the daily numbers games, instant tickets and online play. These are certified by test laboratories, run on secured equipment, and audited. The advantage is speed and cost. The disadvantage, for players, is that you cannot see the draw, and must rely on certification and oversight. See how random number generators work in lotteries.
Famous problems and why audits exist
Lotteries have had integrity problems, usually involving people rather than machines. One widely reported case involved an employee of a multi-state lottery association who installed software that let him predict certain numbers, and was convicted. That is why modern draws involve multiple people, separation of duties, and independent audit. It is also why a verifiable draw design is attractive: the more of the process that is public and checkable, the less depends on any one person's honesty.
How a verifiable draw differs
A verifiable draw replaces "trust the supervisors" with "check the data". The ticket list is published and fingerprinted, the random value comes from a public source nobody controls, and the winners are a fixed calculation that anyone can repeat. It cannot see the physical world, and cannot prove the ticket list is complete, but entrants can check their own ticket is in it. Our draws work this way: see how to verify a draw.
What happens at a typical draw
- 1Officials check the room, the equipment and the cameras, and an independent auditor observes.
- 2A machine and a set of balls are selected at random from several that have been inspected and stored securely.
- 3The balls are loaded and the machine is started. The result is recorded as each ball is drawn.
- 4The numbers are verified by more than one person and compared with the video.
- 5The results are published, and the equipment is secured again for inspection.
What you can and cannot check as a player
- You can watch recordings and read published audit procedures.
- You cannot independently verify that the balls were unbiased or the room secure.
- That is why integrity depends on people, procedures and oversight.
- A verifiable crypto draw offers a different kind of check, based on data rather than observation.
Ready?
A weekly draw you can check yourself.
$5 tickets, a public random value, and every result published with the data to recompute it.
Frequently asked questions
Are lottery draws rigged?
Properly run draws are heavily controlled and audited, and rigging by a machine is not a realistic problem. Integrity failures in history have involved insiders, which is why checks exist.
Do lotteries use computers or balls?
Both. Big jackpot draws usually use balls. Many daily games and online games use certified random number generators.
Can ball machines be biased?
They are tested for it, and the rotation of equipment is designed to prevent any bias being exploited.
How is a crypto lottery draw different?
It can publish its data and use public randomness, so anyone can recompute the result.
Where is Powerball drawn?
At a studio run by a state lottery, in Florida at the time of writing.
Are lottery balls checked for bias?
Yes. Weight, size and behaviour are tested, and sets are rotated.
Can I watch a draw?
Most large draws are streamed or recorded and posted online.