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Coin Flip / Dice Roller

Everyday

Flip a virtual coin or roll any size of dice — D4 to D100. Roll up to 20 dice at once. Instant results, completely free, no sign-up or install required.

What is a Coin & Dice?

The Coin Flip / Dice Roller is a virtual randomisation tool that replicates two of the most common real-world fairness mechanisms — flipping a coin and rolling a die — without needing any physical objects. Switch between Coin Flip and Dice Roll mode, set the number of sides and the count, and each click of Generate produces a fresh, unbiased result instantly.

Coin flips produce Heads or Tails, each with exactly 50% probability. Dice rolls produce a whole number from 1 to N, where N is the number of sides you choose — any value from 2 to 100 is supported, covering the full standard tabletop RPG set (D4, D6, D8, D10, D12, D20, D100) as well as any custom die size. You can roll or flip up to 20 at once, with each result displayed on its own line so individual outcomes are easy to read and record.

Physical coins and dice are not always to hand, and even when they are, rolling multiple dice or logging results for a game introduces friction. A virtual tool removes the friction entirely — no dice to lose, no squinting at tiny faces, no disputes about whether the roll was valid. Every outcome is generated with equal probability and the logic is fully transparent.

For picking a number across an arbitrary range rather than simulating a specific die, the Random Number Generator gives you explicit min and max control. For generating placeholder content to pair with game content or test data, see the Lorem Ipsum Generator.

How to use this Coin & Dice calculator

  1. Select Coin Flip or Dice Roll from the Mode dropdown.
  2. If rolling dice, set Dice Sides to the die type you need — enter 6 for D6, 20 for D20, or any custom number from 2 to 100.
  3. Set Number of Flips / Rolls to how many coins or dice you want to simulate in one click (1–20).
  4. Click Generate — results appear immediately in the Results output box, one per line.
  5. Click the copy button to copy all results to your clipboard in a single action.
  6. Click Generate again any time you need a new set of results; previous results are replaced.

Formula & Methodology

Coin flip: A single call to Math.random() returns a number in [0, 1). If the value is below 0.5, the result is Heads; otherwise Tails. Both outcomes have exactly equal probability.

Dice roll: For a die with N sides, the formula is:

result = Math.floor(Math.random() × N) + 1

This maps the [0, 1) range uniformly onto integers 1 through N. Each face has probability 1/N.

Each flip or roll in a batch is computed by an independent call to Math.random(), so results within a batch are mutually independent — the same face can appear multiple times, exactly as it can with physical dice. The browser's Math.random() implementation is a pseudo-random number generator (typically xorshift128+ or a similar algorithm) seeded by the runtime at page load; it produces sequences that pass standard statistical randomness tests and are suitable for all game and decision-making purposes.
Frequently Asked Questions
What is the Coin Flip / Dice Roller?
The Coin Flip / Dice Roller is a browser-based tool that simulates flipping a fair coin or rolling a die of any size — from a standard D6 to a D100 or any custom number of sides. It generates each result independently using a uniform random algorithm, giving every outcome an equal probability of appearing.
How random are the results?
Results are generated using JavaScript's Math.random(), a pseudo-random number generator seeded by the browser runtime and uniformly distributed across the possible outcomes. For coin flips and dice rolls — where the goal is fairness in a game or decision, not cryptographic unpredictability — this source is more than sufficient. Each flip or roll is statistically independent of every previous one.
Is a coin flip truly 50/50?
Yes — the algorithm treats Heads and Tails as equally probable by checking whether a random number falls below or above 0.5. There is no bias toward either outcome, and each flip is independent, meaning a run of five Heads in a row does not make Tails more likely on the next flip. This is the gambler's fallacy — the tool has no memory between flips.
What dice sizes are supported?
Any number of sides from 2 to 100 — set the Dice Sides field to any whole number in that range. The standard tabletop RPG dice (D4, D6, D8, D10, D12, D20) all work, as does a D100 (percentile dice) or any custom value like a D7 or D30. The coin flip mode always uses exactly 2 sides (Heads and Tails) regardless of the Sides setting.
How do I flip a coin?
Select Coin Flip from the Mode dropdown, set Number of Flips / Rolls to 1 (or more for multiple flips), and click Generate. Each result shows as Heads or Tails in the output list. Click Generate again for a fresh flip.
How do I roll multiple dice at once?
Switch Mode to Dice Roll, set Dice Sides to the die type you want (e.g. 6 for a D6), set Number of Flips / Rolls to the number of dice (e.g. 3 to roll 3D6), and click Generate. Each die result appears on its own line in the output. Copy all results at once using the copy button.
Can I roll non-standard dice like a D20 or D100?
Yes — set Dice Sides to any number from 2 to 100. For a D20 enter 20, for percentile dice (D100) enter 100. Non-standard sizes like D7, D13, or D30 also work. The tool treats any value as a fair die with that many equal faces numbered 1 through N.
Is anything stored or tracked when I use this tool?
No — all generation runs in your browser and nothing is sent to any server. The results exist only on your screen for as long as the page is open; closing the tab leaves no trace.
What does D6 mean?
D6 is shorthand for a six-sided die — the D stands for 'die' and the number indicates how many faces it has. D20 means a twenty-sided die; D4, a four-sided one. This notation comes from tabletop role-playing games like Dungeons & Dragons, where different die sizes determine the outcomes of different types of actions.
Can I use this for tabletop RPGs?
Yes — the tool supports the full standard RPG dice set (D4, D6, D8, D10, D12, D20) and allows rolling multiple dice simultaneously. Enter the die type in Dice Sides, set the count in Number of Rolls, and each die's result appears on its own line. For generating random character names or placeholder dungeon descriptions, pair it with the [Lorem Ipsum Generator](/lorem-ipsum-generator/).
What is the probability of rolling a specific number on a D6?
On a fair D6, each face has a 1-in-6 probability of appearing — roughly 16.7%. This holds for any die size: on a D20, each value has a 1-in-20 (5%) probability. The tool generates each roll independently, so past results have no influence on future ones. For number picking over a custom range, the [Random Number Generator](/random-number-generator/) gives more control over min, max, and count.
Can I use a coin flip to make a decision?
Absolutely — set Mode to Coin Flip, Count to 1, and let the result guide a yes/no or either/or choice. Many people find that a coin flip helps when two options are roughly equal: if you feel relieved or disappointed by the result, that reaction reveals which option you actually preferred. For multi-option decisions, number the options and use the [Random Number Generator](/random-number-generator/) to pick one.

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