Gambling terms, explained straight

Card Games

Mash shuffle vs riffle shuffle

A mash shuffle mixes cards by spreading them face down on a table and sliding them over one another, while a riffle shuffle splits the deck in two and interleaves the halves by releasing cards from the thumbs.

Randomisation time
Mash shuffling achieves statistical randomness after about one minute.1
Also known as
Wash shuffle, smooshing, scramble, Chemmy, Irish, hard shuffle, ice cream, washing the cards.1

Key points

  • A mash shuffle mixes cards by spreading and sliding them together on a table, using friction rather than a thumb release.1
  • A riffle shuffle splits the deck into two halves and interleaves them by releasing cards from the thumbs in an alternating stream.12
  • Mash shuffling is common in casual play; casinos typically use riffle-based shuffling, including repeated riffles, for randomization.13

Where this term is used

Not the same as

  • Casino riffle shuffle — a riffle shuffle performed in a casino setting, often with multiple riffles or a machine, whereas mash shuffle is a manual table mixing method
Card games Riffle shuffle Explains the riffle shuffle technique and its use in card games. Card games Faro shuffle vs riffle Compares the faro shuffle (perfect interleaving) with the standard riffle shuffle. Card games Faro shuffle Describes the faro shuffle, a precise interleaving technique often used in magic. Card games Overhand shuffle Covers the overhand shuffle, a common hand-held shuffling method. Card games Hindu shuffle Explains the Hindu shuffle, a technique popular in India and parts of Asia. Card games Bridge shuffle Describes the bridge shuffle, a riffle-based shuffle often used in bridge.

Sources

  1. Shuffling en.wikipedia.org Defines mash shuffle and riffle shuffle, gives alternative names, and states the one-minute randomisation figure.
  2. Riffle shuffle permutation - Wikipedia en.wikipedia.org Provides the technical definition of riffle shuffle permutation.
  3. Gilbert–Shannon–Reeds model en.wikipedia.org Describes the Gilbert–Shannon–Reeds model and casino riffle shuffling practices.

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.