Tool
Custom Dice Builder
Build a die with your own faces — and give the faces different weights if you want.
Custom Dice Builder
3 faces. Weights are unequal — this is a loaded die, on purpose.
- Yes25.0%
- No25.0%
- Ask again later50.0%
Write your own faces, one per line, and roll them. Add a number after a comma and that face becomes more likely — which makes it a loaded die, deliberately and visibly.
The probability table sits next to the die and updates as you type, because a weighted die is the one randomiser where the odds are completely invisible from the object itself. A weighted spinner wheel shows you its unequal arcs; a weighted die looks exactly like a fair one.
The tool states plainly whether your die is balanced. If every weight matches, it says so; if they do not, it says the die is loaded.
How the Custom Dice Builder works — and why it's fair
The draw is a cumulative-sum walk over the face weights, identical to the mechanism behind the weighted picker: sum the weights, draw one float scaled to that sum, and walk the faces subtracting until the total goes negative. That handles fractional weights and arbitrary face counts without building anything.
A physical die cannot do this. Real dice get their fairness from geometry — identical faces, uniform density — and the only way to load one is to alter that geometry, which is both detectable and imprecise. A digital die's odds are a number, so any ratio is available exactly, and nothing about the object reveals it.
That is why this page leads with the table rather than the die. The core honesty problem with a weighted die is not that weighting is wrong — it is often exactly right — but that unlike an unequal wheel, a loaded die gives an observer no way to notice. Printing the percentages is the only available substitute for the visual cue a wheel gets for free.
The face count is whatever you type. Nothing here is limited to the platonic solids, so a three-sided die, a seven-sided die or a nineteen-sided die all work identically. Physical dice are limited to shapes that can be made fair; this constraint does not exist in software, which is the main practical advantage of a digital custom die.
Faces are text, not numbers, so the results cannot be summed or compared. A die reading Yes, No and Ask again later is a perfectly valid die and a completely useless one to add up — if you need arithmetic, the standard dice roller and the dice pool roller are numeric by design.
A weight of zero removes a face from the draw entirely while keeping it in the list, which is a convenient way to park an option without deleting the line. The table shows it as 0.0% rather than hiding it.
When the Custom Dice Builder is fair — and when it is not
What it does guarantee
- With equal weights, every face has an exactly equal chance regardless of how many faces there are.
- With unequal weights, each face's long-run share converges on the printed percentage.
- The table is always visible and always current, so the odds are never hidden behind the object.
What it does not
- A weighted die is a loaded die. Nothing about the result reveals that, which is why the table has to be shown.
- Text faces cannot be added, compared or summed — the die produces a label, not a value.
- The roll history holds twelve results and is not saved. It is a convenience, not a record of the session.
Two worked examples
A fair three-sided die
- Three faces, all weight 1. Each has an exact 33.3% chance.
- No physical three-sided die can be made fair; a digital one is trivially so.
- The tool reports 'all weights equal, so this is a fair 3-sided die'.
Yes / No / Ask again later at weights 1, 1, 2
- Total weight 4, so the shares are 25%, 25% and 50%.
- 'Ask again later' comes up half the time — a deliberate design choice, not a fault.
- The tool reports the weights as unequal and labels the die loaded.
Dice that do not exist in a shop
Custom game mechanics are the obvious case: a die whose faces are actions, outcomes or NPC reactions rather than numbers, which is a thing tabletop designers build constantly and cannot easily prototype physically.
Deliberately unequal outcome tables are the second, and they are far more common than people admit. A random-event die where the catastrophic result should occur one time in twelve and the mundane result five times in twelve is a weighted die, and building it by writing out twelve equal faces is both tedious and error-prone.
Classroom probability work uses it precisely because the weights are visible and adjustable. Rolling a die that is 60% one face and watching the tally converge on 60 over sixty rolls is a much stronger demonstration than the same lesson with a fair die.
For numeric rolls with modifiers and totals, the standard dice roller is the right tool. For unequal odds over a long list of entries rather than a handful of faces, the weighted random picker is the same mechanism with a table built for scale.
Frequently asked questions
How do I make a face more likely?
Add a comma and a number after the label. Weights are relative, so 1/1/2 and 10/10/20 behave identically.
Is a weighted die still random?
Yes — unpredictable within known odds. Random means unpredictable, not equal, and the table tells you exactly what the odds are.
Why does the page insist on showing the percentages?
Because a loaded die is invisible. An unequal spinner wheel shows its arcs; a die shows nothing, so the table is the only honest substitute.
Can I build a die with an odd number of faces?
Yes, any number. Physical dice are limited to shapes that can be made fair; software is not.
Can I use numbers as faces and add them up?
The faces are text, so the tool will not sum them. For arithmetic, use the standard dice roller or the dice pool roller.
What does a weight of zero do?
It removes the face from the draw while keeping the line in your list. The table shows it as 0.0%.
What if I leave the weight off a line?
It is treated as weight 1. Dropping the face would be far worse, because an absent face is not something you would notice.
Does the roll history persist?
No. It holds the last twelve results in the page and is discarded when you leave.
How is this different from the spinner wheel?
The wheel shows its odds as arc area, so unequal weighting is visible at a glance. A die cannot do that, which changes what the page has to explain.