A weight tells a spin wheel how big each option's share is. An option's chance is its weight divided by the total weight of the options still on the wheel, so weights of 1, 1 and 2 give chances of 25%, 25% and 50%. Keep every weight at 1 when everyone should have the same chance. Raise a weight only when the group can see it and agrees with the reason.
What a weight does: the formula
On the Spin Wheel, every option has a whole-number weight from 1 to 100 next to its name. The chance of a given option being picked on one spin is:
Chance = the option's weight ÷ the total weight of all options currently on the wheel
Each slice is drawn in proportion to its weight, so the slice sizes on the wheel match the odds. After a spin, the result panel shows the approximate chance the picked option had.
| Option | Weight | Calculation | Chance |
|---|---|---|---|
| Noodle bar | 1 | 1 ÷ 4 | 25% |
| Pizza place | 1 | 1 ÷ 4 | 25% |
| Favourite café | 2 | 2 ÷ 4 | 50% |
The formula has two consequences that surprise people:
- Weights are relative. Weights of 2, 2, 4 or 10, 10, 20 give exactly the same chances as 1, 1, 2. Only the ratios matter.
- Adding an option changes every chance. If you add a fourth option with weight 1, the total becomes 5. The café drops from 50% to 40%, and each of the other three gets 20%.
How chances change in Draw without replacement
In Draw without replacement mode, the option picked on one spin is removed before the next spin. The formula doesn't change, but the total gets smaller, so every remaining chance is recalculated.
| Option | Weight | Spin 1 | Spin 2 if Noodle bar was picked | Spin 2 if Favourite café was picked |
|---|---|---|---|---|
| Noodle bar | 1 | 25% | removed | 50% |
| Pizza place | 1 | 25% | 33.3% | 50% |
| Favourite café | 2 | 50% | 66.7% | removed |
Weights mean something different in this mode. Every option gets picked once per round, so a higher weight does not make an option come up more often. It makes the option more likely to come up earlier. In the example, the café is picked first half the time and ends up last only one time in six (about 16.7%). Each weight-1 option ends up last about 41.7% of the time.
When weights make sense
A simple test: you can state the reason in one sentence, and the people it affects accept that reason.
- A favourite restaurant. The family agrees the café is everyone's favourite, so it gets weight 2 instead of 1. It still won't win every time. It just wins more often.
- Chores where someone has already done more. Sam took the bins out three weeks running. For this week's draw, give Sam weight 1 and the other two housemates weight 2 each. Sam's chance drops to 20%, and the others each get 40%.
- Giveaway entries earned by taking part. A book club giving away a free book could count one entry per meeting attended, so someone who came to four meetings gets weight 4. Entries come only from taking part, never from paying.
When equal weights are fairer
- Nobody has a clear claim to extra chances, as with "who goes first" or "which film tonight".
- The person running the wheel would be setting the weights alone, without the group agreeing to them.
- You are picking people in a class, team or meeting. A higher or lower weight on a person looks like favouritism, even when it's meant kindly. Our guide to random name pickers for the classroom keeps every student equal.
- You wouldn't accept the low-weight result anyway. If an option at 1 against 99 would be rejected the moment it came up, take it off the wheel.
Draw without replacement: assign each item once
Use this mode when every option must be used exactly once, such as for a turn order, a rota, or one task per person in a fixed list.
- Enter your options and check the weights. For an order, all 1 is usually right.
- Switch the mode from Classic to Draw without replacement.
- Spin and write the result down as position 1.
- Spin again. The last pick is removed first, and a counter shows how many options have been picked and how many are left.
- When the round is complete, choose New round to bring all the options back.
After the first pick, the option list stays locked until you start a new round. Nobody can quietly change a weight halfway through.
Importing options and weights from a CSV file
For a long list, Import CSV is quicker than typing. You can start from Download CSV template or write the file yourself in a spreadsheet or text editor. The rules are:
- One option per row, in the first column.
- The second column is optional and holds the weight, a whole number from 1 to 100. A blank or invalid weight counts as 1, and anything above 100 counts as 100.
- Columns can be separated by commas or tabs.
- The first row is skipped as a header if its first cell contains "option", "name" or "text" (or the Chinese 选项).
- Importing replaces the options that are on the wheel.
Here is the book-club giveaway as a file, with each weight equal to the number of meetings attended:
name,weight
Amira,3
Ben,1
Chen,2
Dana,4
The total weight is 10, so Amira has a 30% chance, Ben 10%, Chen 20% and Dana 40%.
Always start the file with a header row such as "name,weight". A header like "Member" or "Student" isn't recognised, so it would end up as an option on the wheel.
Sharing a wheel, and what the other person sees
Open Share this wheel in the wheel settings and choose Copy settings link. The link stores the option names and weights for 2–50 options, each up to 80 characters, with weights from 1 to 100. Anyone who has the link can read them, so check the list before you send it.
When someone opens the link, they see a preview that lists every option with its weight. Their wheel doesn't change until they choose Use this wheel, which replaces their current wheel and starts a new round. Dismiss keeps their own wheel.
The link shares the wheel, not a result. Each spin is a new random draw on the device where it happens, so agree in advance whose spin counts.
Mistakes to avoid
- Changing weights after seeing a result. If you nudge the weights and spin again until the "right" answer comes up, the wheel is only decoration. Fix the weights before the first spin. If you already know what you want, just choose it.
- Too many options to read. With lots of slices, long labels are shortened on the wheel, and a weight-1 option next to heavy ones becomes a thin sliver. If people are watching from across a room, keep the list short (about a dozen is a good limit) and read the winner from the result panel.
- Ambiguous labels. "Italian" doesn't help if there are two Italian places nearby, and neither does "Sam" if two people are called Sam. Make the first few characters of each label distinct. Don't list an option twice either, because two "Pizza" slices quietly double its weight.
- Forgetting removed options. After a Draw without replacement round, or if you deleted options last time, the wheel may not contain what you think. The last wheel is restored when you return in the same browser, so read the list before you spin.
Make the spin transparent
- Show everyone the options and weights before spinning, either on a shared screen or by sending the share link.
- For every weight that isn't 1, say the reason in one sentence.
- Agree on re-spins before the first spin. For example, you only re-spin if the result is impossible, such as the restaurant being closed, and the second result stands.
- Have one person spin while everyone watches. The result panel shows the chance the winning option had.
- Be clear about what the wheel is. Results come from the browser's built-in Math.random() function, and the site can't preset outcomes. That is fine for everyday decisions, but not for anything that needs a formal, audited draw. If you're curious, here is how browser random numbers work.
In short: start with every weight at 1, add a weight only for a reason everyone accepts, show the wheel before you spin, and use Draw without replacement when each option should come up exactly once.