RanNum - Random Number Generator
RanNum picks a random whole number between two limits you set. Type a minimum and a maximum, tap Generate, and a number appears in large digits in the middle of the screen. Both limits are included, so a range of 1 to 6 can give 1, 2, 3, 4, 5 or 6, just like a die.
It is made for the small decisions where a neutral pick helps: who goes first in a game, which raffle ticket wins, which question to practise next, which page of a book to open, or which of several equally good restaurants to try. Teachers use number pickers to call on students by register number, and families use them to settle whose turn it is.
The range you typed is saved in your browser, so the next time you open RanNum the same minimum and maximum are ready. If you have never set one, it starts at 1 to 100.
The app runs entirely in your browser. What you enter is saved only on this device.
How to use RanNum
- Set the minimum. Type the lowest number you want in the Min box. Negative numbers work too, for example -10.
- Set the maximum. Type the highest number in the Max box. It must be equal to or larger than the minimum.
- Generate. Tap Generate. A random number from the range, including both ends, appears in large digits at the top.
- Pick again. Tap Generate as many times as you like. Each tap is a fresh, independent pick, so the same number can come up twice in a row.
- Come back later. Your Min and Max are saved as you type, so they are still there the next time you open the page in this browser.
Features
- Random whole numbers between any minimum and maximum
- Both ends of the range included
- Negative numbers supported
- One-tap generation with a large, easy-to-read result
- Remembers your last range in this browser
- Starts at 1 to 100 the first time
- No account and nothing to install
Using random numbers fairly
Every number has the same chance
With a uniform random pick, every whole number in the range is equally likely. In a range of 1 to 20, each number has a 1 in 20 chance (5%) on every tap. That is what makes a number picker fair for choosing a winner or deciding an order: nobody's number is favoured.
Repeats are normal
Each pick is independent of the previous ones, so the same number can appear twice in a row. People often feel this is suspicious, but it isn't. If you pick 10 numbers from 1 to 30, the chance that at least two of them match is roughly 80%, a version of the well-known birthday problem. If you need each number only once, such as drawing a running order, keep a list of numbers already chosen and tap again when a repeat comes up.
Turning numbers into choices
Almost any random choice can be made with a number. Number the options and set the range to match: three restaurants become 1 to 3, a class of 28 becomes 1 to 28, a deck of cards becomes 1 to 52. For a coin flip, use 1 to 2; for a standard die, 1 to 6; for two dice, pick twice from 1 to 6 and add them rather than picking from 2 to 12, because the totals of real dice are not equally likely (7 comes up most often).
Running a fair draw
For a raffle or giveaway, write down the list of entries and their numbers before you generate, agree the range in advance, and generate once in front of the participants or on a shared screen. Deciding the rules first, such as whether a repeated or invalid number means you pick again, avoids arguments later.
Know the limits
Browser random number generators like the one used here are fine for games, classrooms and everyday decisions. They are not meant for security purposes such as creating passwords or encryption keys, and they should not be used for anything where money depends on the outcome being unpredictable to an attacker.
Frequently asked questions
Are the minimum and maximum included?
Yes. A range of 1 to 10 can return 1, 10 or anything in between.
Can it give decimals?
No. RanNum only picks whole numbers. For one decimal place, you could pick from 0 to 100 and divide the result by 10 yourself.
What happens if the minimum is bigger than the maximum?
No number can be picked. Make sure Min is equal to or smaller than Max, then tap Generate again.
Is there an upper limit?
Yes. Very large maximums (above about 4.29 billion) are beyond what RanNum handles, and it shows a surprised face instead of a number.
Where is my range stored?
Only in this browser on this device. There is no account and nothing is uploaded. Clearing browser data or using a private window resets it to 1 to 100.
Does it keep a history of results?
No. Only the latest number is shown. Note down results you need to keep.
How is the web version different from the phone app?
The generator works the same way. The iPhone and Android apps let you use it without opening a browser.
Limitations of the web version
- Whole numbers only
- No history of previous results
- No option to prevent repeats
- Not suitable for passwords or security uses
Phone app
RanNum is also available as an app for phones and tablets: