Rangdom

About percentile dice (D100)

Percentile dice — commonly written as D100 — produce a result from 1 to 100. They are traditionally rolled as a pair of ten-sided dice: one is the tens die, marked 00, 10, 20, … 90, and the other is the units die, marked 0–9. The two are read together, so a tens roll of 70 and a units roll of 5 reads as 75.

When both dice land on zero (00 + 0), the result reads as 100 — the maximum value — rather than zero. This roller shows that tens/units breakdown alongside the combined 1–100 result, so it reads the way percentile players expect.

Probability

Each value from 1 to 100 is equally likely, with an exactly 1% chance per outcome. The expected value of a single D100 roll is 50.5.

Use cases

• Call of Cthulhu skill and characteristic rolls
• Warhammer and RuneQuest percentile checks
• Old-school D&D thief skills and percentage chances
• Roll-under and roll-over percentile resolution
• Random tables and loot drops measured in percentages
• Any check phrased as "roll under X%"

How it works

1. Your browser rolls a tens die (00–90) and a units die (0–9) using cryptographically secure randomness
2. The two digits are combined into a value from 1 to 100, with 00 + 0 reading as 100
3. The result and its tens/units breakdown are displayed instantly — no server request needed
4. Roll count and recent history are tracked locally

Privacy and security

Your dice rolls never leave your device. This tool runs entirely in your browser using client-side JavaScript — no generator API calls, no server-side generation, and no storage of generated values.