How to Balance Dice for Fair Play: A Practical Salt Water Test

Quick answer

The practical way to check dice balance at home is the salt water float test: dissolve enough salt in water that a die floats, spin it a few times, and watch which face keeps coming up. It is a screening tool, not a lab test. A die that always settles on the same face is worth retiring; a die that floats and tumbles randomly is fair enough for normal play.

If a d20 keeps betraying you on the roll that matters, you do not need a laboratory to find out whether the die itself is the problem. A glass of water, a lot of salt, and five minutes will tell you more than another night of blaming your luck.

This guide walks through the salt water float test step by step, explains what the result actually means, and covers when to test, which dice are worth testing, and when to stop worrying and just roll.

What the salt water test can and cannot prove

The salt water float test checks whether a die is denser on one side than another. Dissolve enough salt and the water becomes dense enough that most plastic, resin, and acrylic dice float. A floating die can rotate freely, so if one face is heavier, that side sinks and the opposite face rises. Repeat the spin and a biased die tends to show the same face again and again.

What it cannot prove is that a die is perfectly random. A die that passes the float test may still have slightly uneven faces or rounded edges that nudge results. It also says little about solid metal dice, which are far too dense to float in any salt solution you can mix at home. Treat the test as a screening tool: it catches obvious bias, not subtle imperfection.

• Test one die at a time; a crowded glass hides the result.
• Use a clear glass or jar so you can watch the die from the side.

Set up your salt water test

Fill a clear glass or jar about three-quarters full with warm water, then stir in salt a spoonful at a time until it stops dissolving easily. Warm water holds more salt, so start warm and let it cool if you like. You want a solution dense enough that your die bobs at the surface rather than sinking.

Drop in a single die and watch. If it sinks, add more salt and stir until it dissolves, then try again. If it floats, you are ready to test. Keep a towel nearby, and work over a sink or tray so a slippery die does not end up on the floor.

• Skip carbonated water; bubbles cling to the die and skew the float.
• Do not test painted or plated dice for long periods, since prolonged soaking is unnecessary and can dull a finish.

Run the float test and read the results

Give the floating die a gentle spin with your finger, wait for it to settle, and note which face points up. Repeat at least ten times, and ideally twenty, recording each result. A fair die should show a mix of faces with no obvious pattern. A biased die will keep returning to the same face, or a small set of faces, far more often than chance would suggest.

If one face comes up more than roughly half the time across twenty spins, that die has a real bias worth acting on. If the results look scattered, the die is fine for casual play. Remember that a small sample is noisy, so a single repeated face in five spins means very little.

• Write results down; memory favors the dramatic rolls, not the pattern.
• Test the same die on two different days before you decide.

Which dice are worth testing

The float test works best on solid plastic, resin, and acrylic dice. It is most useful for handmade or cast dice, where a void or a heavy inclusion can shift the center of mass. Mass-produced acrylic sets are usually consistent enough that testing is optional, though it is a fun way to spend a rainy game night.

Metal dice are a different story. They are dense enough that no home salt solution will float them, so the float test simply does not apply. For metal dice, the practical fairness check is visual and tactile: look for malformed faces, check that the die sits flat on each face, and listen for a clean roll. If a metal die wobbles on a flat surface or shows an obviously misshapen face, that is a real defect worth a closer look.

• Test your most-used d20 first; it has the most chances to betray you.
• A d6 from a board game is usually not worth testing unless it feels off.

When a die fails the test

A biased die does not have to go in the trash. Many tables keep a known-biased die as a designated villain die, a prop for a cursed item, or a spare for a guest who forgot theirs. If you play in a group that cares about dice fairness, though, the honest move is to pull the die from play and say so.

If the die is new and clearly defective, such as a visible bubble or a warped face, that is a manufacturing problem rather than a balance one, and it is worth contacting the seller. For handmade and cast dice, small variations are normal and expected; the float test helps you separate normal variation from a die that is genuinely lopsided.

• Mark biased dice with a small sticker or a dot of paint so they do not sneak back into the pool.
• Never quietly swap in a biased die for a high-stakes roll; that is the opposite of dice fairness.

The salt water balance test, step by step

1. Step 1: Mix a saturated salt solution: Fill a clear glass three-quarters full with warm water and stir in salt until it stops dissolving. Warm water holds more salt, so start warm and let it settle. Checkpoint: a test die should bob at the surface instead of sinking.
2. Step 2: Float one die at a time: Drop in a single die and watch whether it floats. If it sinks, add more salt, stir, and try again. Keep the glass over a tray or towel. Common mistake: testing several dice at once, which makes the results impossible to read.
3. Step 3: Spin and record twenty times: Give the floating die a gentle spin, let it settle, and note the top face. Repeat twenty times and write each result down. Checkpoint: a fair die shows a spread of faces, not one face over and over.
4. Step 4: Repeat on another day: Run the same test again later before you decide. Small samples are noisy, and a single session can mislead you in either direction. Common mistake: condemning a die after five spins.
5. Step 5: Retire, repurpose, or keep rolling: If one face dominates across two sessions, pull the die from serious play. Keep it as a villain die or spare, or contact the seller if it is new and visibly defective. Next step: mark biased dice so they do not drift back into your main set.

Dice worth testing at your table

• Adventure Begins - Scigate Copper: Solid metal dice, die-cast non-toxic zinc alloy with battleworn copper plating, sold as a standard 7-piece RPG set. Metal dice will not float in a home salt solution, so judge them by face shape and how flat they sit rather than by the float test.
• Adventure Begins - Gravehold w/ Bloodspatter: Battleworn silver with stark red paint spatters, part of the Adventure Begins Collection, sold as a standard 7-piece RPG set. Decorative paint and plating mean you should keep any water exposure brief and dry the dice thoroughly afterward.
• Infinity d20 Set - Aleph: A single d20 die electroplated with a bright yellow/golden finish, made from die-cast non-toxic zinc alloy. A single-die set is easy to inspect face by face, which is the practical fairness check for metal dice.

A salt water float test takes five minutes and settles most arguments about dice integrity before they start. Test your most-used dice, record the results honestly, and retire the ones that fail. For metal dice, skip the water and inspect the faces instead. Either way, you will roll with more confidence once you know what is actually in your dice bag.