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Random Number Generator

YSometimes you need a number that is genuinely random — not the first one that comes to mind, not a guess, not a pattern. A teacher picking a student, a developer testing an input, a group deciding who goes first, a gamer rolling for initiative. Whatever the reason, this free tool gives you a truly random result instantly.
Set your minimum and maximum, click generate and the number appears. No ads, no signup, nothing stored.

Is This Random Number Generator Truly Random?

diece roll game- random number generator

Technically it is pseudorandom — generated by a mathematical algorithm rather than a physical process. For cryptographic or security purposes you would need a dedicated cryptographically secure generator. For everything else — raffles, games, decisions, teaching, testing — this generator is perfectly suitable and statistically well-distributed.

What People Use a Random Number Generator For

Teachers and educators — pick a random student to answer a question without appearing to favour anyone. Set the range to 1 to the number of students and generate. Fair, instant and students cannot predict who is next.

Raffle and prize draws — assign a number to each entry, set the range to match and generate the winner. Use the no duplicates option when drawing multiple prizes to ensure each entry can only win once.

Everyday decisions — deciding who pays the restaurant bill, picking a movie when the group cannot agree, choosing the order for presentations, selecting who does the dishes. A random number generator removes bias, ends arguments and takes the responsibility off everyone.

Developers and testers — generate test data, random IDs or sample inputs for software testing without thinking up values manually. The multiple numbers option with no duplicates is useful for generating unique test identifiers.

Tabletop RPGs and board games — the dice roller covers all standard RPG dice sizes including D20 for Dungeons and Dragons, D10 for various systems and D100 for percentile rolls. Roll multiple dice simultaneously and see each result alongside the total.

Lottery number selection — set the range to match your lottery numbers, set quantity and enable no duplicates. The random number generator does not improve your odds — lottery draws are independent events — but it removes unconscious patterns from manual selection and gives you a fully random set of numbers in seconds.

Dice Sizes — What Each One Is Used For

Dice

Sides

Common use

D4

4

Damage rolls in D&D, some board games

D6

6

Standard dice, most board games, Yahtzee

D8

8

Weapon damage in tabletop RPGs

D10

10

Percentile rolls, World of Darkness

D12

12

Great axe damage in D&D, some RPGs

D20

20

Attack rolls and skill checks in D&D

D100

100

Percentile rolls, wild magic tables

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Frequently Asked Questions

Enter your minimum and maximum values in the Number tab then click Generate. For a number between 1 and 100 leave the defaults and click Generate. For 1 to 10 change the maximum to 10. For 1 to 1000 change the maximum to 1000. Any range works — including negative numbers.

The random number generator defaults to a range of 1 to 100. Click the Generate button or click anywhere on the result box and a random number between 1 and 100 appears instantly. Each number has an equal probability of being selected.

Divide the percentage by 100 and multiply by the number. Example: what is 20% of 350? Answer: 20 ÷ 100 × 350 = 70. Use the “What is X% of Y” tab — the step-by-step solution shows the working automatically.

Yes — switch to the Multiple Numbers tab, enter your range and quantity, tick the No duplicates box and click Generate. Each number in the results will appear only once. Note that the quantity cannot exceed the size of the range when no duplicates is enabled — you cannot generate 20 unique numbers from a range of 1 to 10.

Switch to the Dice Roller tab, click D20 to select it then click Roll Dice. To roll multiple D20s simultaneously increase the number of dice before rolling — the result shows the total alongside each individual roll.

Yes — each coin flip is an independent random event with exactly 50% probability of heads and 50% probability of tails. Previous flips have no effect on future flips. Streaks of the same result are completely normal in any random sequence — getting five heads in a row does not make tails more likely on the sixth flip.

Up to 100 numbers at once using the Multiple Numbers tab. Set your minimum, maximum and quantity then click Generate. Enable no duplicates to ensure each number appears only once in the results.

A truly random number comes from a physical unpredictable process such as radioactive decay or atmospheric noise. A pseudorandom number is generated by a mathematical algorithm producing results that appear random and are statistically well-distributed. For everyday use — games, decisions, raffles, testing — pseudorandom numbers are indistinguishable from truly random ones in practice.

Yes — set the range to match your lottery (1 to 49 for the UK National Lottery main draw), set quantity to 6 and enable no duplicates. Randomly generated lottery numbers have exactly the same odds as any other selection. Each lottery draw is an independent event and no number selection method changes your probability of winning.

Yes — it works on any device with a web browser. No app to download, no installation required. All four modes — number, multiple numbers, dice roller and coin flip — are fully responsive and work on desktop, tablet and mobile.

About This Random Number Generator

This random number generator is part of CalcDaysTime — a free suite of date, time and maths tools. All generation happens entirely in your browser. No numbers are sent to our servers, stored or logged in any way.

Disclaimer: Numbers generated by this tool are pseudorandom and suitable for games, decisions and general use. They are not cryptographically secure and should not be used for security-critical applications such as password generation or encryption keys.