How Online Bingo Random Number Generators Are Tested
Online bingo software needs a way to generate and use random
outcomes. In Great Britain, the relevant rule is not that every number
must “look random” to a player. The Gambling Commission’s Remote
Gambling and Software Technical Standards require operators and software
suppliers within scope to be able to demonstrate, to a high degree of
confidence, that the generator and game outcomes are acceptably
random.
This guide explains what that means for remote bingo, what
independent testing examines and what a player can realistically verify.
It does not claim that Bingonotongamstop.com has tested any named game,
supplier or operator.
Which standard applies
to remote bingo?
RTS 7 covers the generation of random outcomes and expressly applies
to gaming, including bingo. The Commission’s annex also marks RTS 7 as
applicable to bingo and explains the additional position for games
offered across multiple premises by remote communication.
The standard sits within the Great Britain licensing framework. It is
evidence about what a Gambling Commission licensee must satisfy, not
proof that every bingo website worldwide follows the same test process.
Start by checking the legal operator, exact web domain and licence
status. The separate guide on how
to check whether an online bingo site is licensed explains that
verification process.
What “acceptably random”
means
RTS 7A says random number generation and game results must be
acceptably random. Compliance can be demonstrated through statistical
analysis using generally accepted tests and methods.
The Commission’s implementation guidance identifies several
properties an RNG should demonstrate:
- Distribution: output should be uniformly
distributed across its full range, while game outcomes should follow the
expected or theoretical probabilities. - Unpredictability: it should be computationally
infeasible to predict the next software-generated number without
complete knowledge of the algorithm and seed. - No repeated or synchronised streams: the generator
should not fall into the same output cycle, and separate instances
should not synchronise into identical streams. - Safe seeding and re-seeding: the method used to
initialise the generator must not introduce predictability. - Unbiased scaling: converting raw RNG output into
the range a game needs must preserve the required random
properties.
These are technical properties. A short personal playing history
cannot establish whether they are satisfied. Streaks and repeated
numbers can occur in random sequences, so an unusual-looking session is
not, by itself, evidence that the RNG has failed.
How random inputs
become bingo outcomes
An RNG produces inputs. The game then maps those inputs to bingo
numbers, tickets or other outcomes according to its rules. RTS 7B
requires games to be implemented fairly and in line with the rules and
prevailing payouts described to the customer.
The mapping matters as much as the raw generator. The Commission says
random inputs must be used in the order received and may not be
discarded to change outcomes. A number outside the expected range should
produce an error that is logged and investigated, rather than being
silently replaced to create a preferred result.
The rules, payouts and outcome probabilities may not be changed while
a game is available except where the rules already provide for a
legitimate change. For bingo, the odds of winning may legitimately
depend on the number of entrants. That is different from altering the
RNG or secretly changing the mapping during play.
Software RNG versus
mechanical ball mixing
Most online-only bingo uses software, but bingo can also use physical
equipment or a mechanical ball-mixing process. The remote technical
standard recognises games that use the laws of physics to generate
outcomes. Mechanical pieces should not degrade or be altered, and
players should not be able to touch or manipulate the mechanism.
Separate Bingo and Casino Technical Requirements add detail for bingo
equipment used in the situations covered by those requirements. They
require acceptably random results and, for an air-mixing device, player
visibility of the mixing action and protection against changing the
placement of balls at the exit. Those equipment rules should not be
confused with a claim that every online game uses a physical blower.
What an approved test house
checks
The Gambling Commission’s testing strategy says external assurance
mainly applies to fairness elements of RNG-driven products such as
bingo. New products within scope must be adequately tested before
release, with evidence supplied to the Commission.
Approved test houses can examine:
- documentation describing how the RNG is implemented;
- whether the algorithm or hardware has known weaknesses;
- source code and relevant scaling or mapping components;
- statistical output and theoretical probabilities;
- game play against the published rules;
- whether a release or later change needs additional external
testing.
The Commission maintains a list of approved test houses. Approval is
not universal for every testing area, so the licensee must use a test
house accredited for the relevant product and requirement.
Some licensees responsible for games testing also face annual
games-testing audits. Those audits sample major and minor updates and
check whether changes were classified and tested appropriately. They do
not turn a single audit into a promise that a player will win or that
every short session will match a theoretical average.
What players can check
themselves
A player cannot reproduce source-code analysis from the game screen,
but several public checks are still useful:
- Verify the legal operator and exact domain in the Gambling
Commission public register. - Read the game rules before buying tickets, including how numbers are
drawn, how prizes are allocated and whether entrant numbers affect the
chance of winning. - Check that the result and the value of any winnings are displayed
clearly. - Save the ticket, transaction record, game identifier and result if
something appears inconsistent. - Use the operator’s complaint process if the published rules and
recorded outcome do not match.
An operator may use a supplier’s software, but the licensing and
testing chain should still be identifiable through the entities
responsible for manufacturing, supplying and operating the gambling
software. A logo saying “certified” is not a substitute for checking the
operator’s licence and the meaning of the certification.
What RNG testing does not
prove
RNG testing is designed to assess technical compliance and fairness.
It does not prove that:
- a particular ticket will win;
- a losing streak is impossible;
- a game has been tested by this website;
- every offshore operator follows Gambling Commission rules;
- a promotional claim accurately describes the game;
- a licensed operator can never make an operational error.
The sensible conclusion is narrower: within the Great Britain
remote-bingo framework, random generation, mapping and game behaviour
must meet defined standards, and the testing strategy requires
independent assurance for important fairness elements.
Official sources checked
Sources checked 11 October 2026: Gambling
Commission RTS 7 — Generation of random outcomes, the RTS
annex showing applicability to bingo, the testing-strategy
summary, the testing
procedure and the approved
Test Houses guidance.
