How to pick a random winner fairly — and prove it

A raffle at a school fair, a social media giveaway, a team prize, a rota: whenever a winner is picked at random, people want to know it was fair. A sound method is simple, and a little record-keeping makes it easy to show.

Step 1: make a clean list of entries

1. Collect all valid entries in one list, one per line.
2. Remove duplicates if each person should have one entry, with Remove Duplicate Lines. Turn off case sensitivity so “Ann” and “ann” count once.
3. Remove entries that break the rules — late, ineligible, incomplete — before the draw, not after.
4. Number the final list from 1 upwards and save a copy.

Step 2: draw the winner

1. Open the Random Number Generator.
2. Set the range from 1 to the number of entries. Both ends are included.
3. For several prizes, set how many numbers you need and turn off duplicates, so no one can win twice.
4. Generate, and match the numbers to the list.

The numbers come from your browser's cryptographically secure random generator, using a method that makes every number equally likely. With duplicates off, numbers are drawn without replacement, exactly as in a lottery draw.

Step 3: make it checkable

The draw itself leaves no trail, so the record has to come from you. For anything people care about:

• Publish or share the numbered entry list, or the number of entries, before the draw.
• Record the screen while you generate the number, or draw it live.
• Note the date, time, range and result.
• Announce the result with the winning number as well as the name.

Extra entries

Some giveaways give extra entries — one for following, another for sharing. The fair way to handle that is to list each entry separately: a person with three entries appears on three numbered lines. Every line then has the same chance, and a person with more entries has proportionally more chance, which is what the rules promised. Skip the duplicate-removal step in that case, and decide in advance whether one person can win more than one prize.

Drawing for a running order or teams

To put a whole list in random order — for presentation slots, a rota or seating — use the random option in Sort Lines. It shuffles the lines so every possible order is equally likely. To split people into teams, shuffle the list and divide it into consecutive groups.

Mistakes that make a draw unfair

• Re-drawing until you like the result. Decide in advance what happens if the winner is ineligible or does not respond — usually, draw again from the remaining entries — and stick to it.
• Changing the list after drawing. Freeze it first.
• Biased shortcuts, such as picking a comment by scrolling and stopping, or taking the first person who replied.

Rules and law

Prize draws and giveaways are regulated in many countries, and social media platforms have their own promotion rules. For competitions with valuable prizes, paid entry or many entrants, check the rules that apply before you start. Keep the entry list and your record of the draw for a while afterwards in case anyone asks.