Random Number Generator, Dice & Coin
Generate random numbers, roll dice, or flip a coin. Your work stays on this device whenever possible.
How to use Random Number Generator, Dice & Coin
- Choose "Generator Mode": Random Numbers / Range, Dice Roller (RPG & Tabletop), Coin Flipper (Heads or Tails) or Random List Picker & Shuffler.
- Pick a "Randomness Source": the cryptographic option, or the reproducible Mulberry32 option, which uses the text in "Seed String (if seeded selected)".
- For numbers set Minimum, Maximum, "Quantity to generate", "Allow Duplicates", Sorting and Separator; for dice type an expression such as 4d6 + 2 in "Dice Notation Expression" or click a d4 to d100 button.
- For coins enter "Number of coins to flip"; for the picker put one item per line, set "Number of winners / items to pick" and choose a "List Action".
- Press "Generate random result", then use "Copy result" or "Download TXT".
Worked example
Choose Random Numbers with minimum 1, maximum 100, quantity 5, duplicates allowed, unsorted, seeded source and the seed lucky-777. The output is 92, 72, 68, 9, 98 every time. Switching to Dice with the seed unchanged and the expression 4d6 + 2 gives rolls 6, 5, 5, 1 and a total of 19.
When to use this tool
- Drawing five raffle winners from a list of names pasted into the picker.
- Rolling a d20 with a modifier during a tabletop game without physical dice.
- Generating a repeatable sample of numbers for a spreadsheet exercise.
Important limitations
Cryptographic mode utilizes window.crypto.getRandomValues; seeded mode uses deterministic 32-bit PRNG for reproducible runs. Browser tab memory limits generation to 10,000 items per batch.
Frequently asked questions
When should I use the seeded source?
When you need the same result again, for instance for a classroom demo or a fair draw someone else can repeat. The same seed and settings always give the same output. It is not suitable for security or gambling.
Are there hidden limits?
Yes, and they are applied silently. Quantity is capped at 5000, coins at 1000, dice at 100 per roll and 1000 sides. Ask for 500d6 and you get 100 dice with the label showing 100d6, so check the printed expression.
What dice notation works?
Only the form NdS with an optional plus or minus number, such as 3d6, 1d20+5 or 2d8-1. Keep-highest, exploding and multi-term expressions are not supported, and the message tells you when the format is wrong.
How does unique mode behave?
Numbers are drawn without repeats and the tool refuses a request for more values than the range holds. For the list picker, the unique action picks distinct entries, so asking for more winners than lines is limited to the list length.
Is the coin flipper fair?
Each flip is an even split from the chosen source. Streaks in a short run are normal, and the longest heads and tails streaks are printed to illustrate that.