Gambling terms, explained straight

Racing & Pari-Mutuel

Pari-mutuel slot machine

A machine that looks and plays like a slot but calculates payouts from a shared betting pool instead of a fixed pay table.

Also called
Historical horse racing (HHR), Instant Racing, tote-based machine13
How it works
Wagers go into betting pools tied to outcomes; winners share the pool after deductions1
UK legal term
Legislation defines a "totalisator" as the apparatus for pari-mutuel betting3

Key points

  • Pays from a shared pool, not a fixed pay table, so the payout depends on total bets and the number of winners1.
  • Often uses replays of past horse or dog races to determine outcomes, making it a form of racing-linked gambling1.
  • Distinct from a standard slot machine because the house edge comes from pool deductions, not a programmed return-to-player percentage.

Where this term is used

Not the same as

  • Pari mutuel — the underlying pool-betting system itself, not the machine that uses it2
Racing Pari mutuel machine Explains the broader category of machines using pari-mutuel payout logic. Racing Pari mutuel Covers the pool-betting system that underpins these machines. Racing Pari-mutuel payouts Details how winnings are calculated from the pool after deductions. Racing Pari-mutuel horse racing Applies the system to live horse-race betting. Racing Pari-mutuel betting example Walks through a concrete payout calculation. Racing Pari-mutuel meaning lottery Compares the pool system to lottery-style prize funds.

Sources

  1. Historical horse racing en.wikipedia.org Defines the term and explains the pool-based payout mechanism.
  2. Parimutuel betting en.wikipedia.org Describes the pari-mutuel betting system that the machine uses.
  3. 2007 No. legislation.gov.uk Provides the UK legal definition of a totalisator, which covers these machines.

Sources are drawn from regulators, universities and published research, and each one is labelled with what it actually is — a preprint is not called a paper. Bookmaker and affiliate pages are never cited here, because a page that sells betting is not a neutral authority on it.

Written and maintained by Ellis Warrender, writer and maintainer.

Last updated 28 July 2026. Spotted an error? Tell me and it gets fixed and logged on the corrections page.