In the crucial moment of a team battle, you confidently roll a d20—and suffer another crushing defeat. All night long, the 20 side seems to be blocked, while the 1 side keeps appearing. You wonder: Am I cursed by bad luck?
Don't doubt yourself and don't defend the dice. Let's investigate together whether it's simply luck or if the dice are inherently biased.
A die with an unbalance center of gravity is like a bobblehead; no matter which way you push it, it always ends up in the middle. Today, we'll show you how to identify these "biased dice" and ensure that every roll is fair and just.
What are biased dice?
A perfectly balanced die has a uniform internal density, with each face having an exact probability of appearing (5% for D20). However, in actual factory or hand-made production, accidents can happen.
-
Trapped air bubbles: A tiny bubble hides inside the resin as it hardens, making one corner lighter.
-
Uneven fillings: Glitter or pigment isn’t mixed evenly, so one side ends up heavier.
- Lopsided finishing: One edge gets polished down a bit too much, and the center of gravity quietly shifts.
The result is that with this biased cube, the heavier side tends to sink to the bottom, while the lighter side rises. If the bottom face corresponding to the 20 is actually a 2, and the 2 face is heavier, the 20 will rarely appear, almost as if it's avoiding you.
Note: tiny imperfections barely affect randomness. Only noticeable bias is worth worrying about. Most brand-name dice are perfectly fine.
Quick Self-Checks: Give Your Dice a Home Physical
No special equipment required. Just a few minutes and you can give your dice a basic screening.
Method 1: The Saltwater Float Test (Classic & Effective)
Best for: Clear or translucent resin dice, acrylic dice
Not for: Metal dice, gemstone dice, or dice with metallic powder (they won't float)
You'll need:
- A clear glass (so you can see inside
-
Warm water (dissolves salt better）
- Table salt or Epsom salt (Epsom salt gives higher density)
Steps:
1.Fill the glass with warm water and keep adding salt while stirring until no more dissolves (a little sediment at the bottom is fine).
2.Gently place your die into the saltwater.
3.Push it under the surface with your finger, then let go.
What to look for:
- If the die floats randomly and stops in different positions when you nudge it → good balance ✅
-
If the die keeps bobbing back to the same face (e.g., always 2 up) → likely biased ❌
tip: Try it a few times. Spin the die in the water and see if it stubbornly returns to the same orientation.
Method 2: The Roll-and-Record Test
This method works for dice of most materials.
You'll need: Paper, pen, a dice tray (or a soft surface), and at least 50 rolls.
Steps:
1.Keep your rolling method consistent: drop the die from the same height (about 12 inches / 30 cm) each time. Don't try to spin it on purpose.
2.Record every result on paper.
3.After 50 rolls, count how many times each face came up.
Quick reference (for a D20)：
-
Expected average: 5% per face (about 2–3 times out of 50).
-
If one face shows up more than 8 times (16%+) → suspicious.
-
If one face shows up 0 times while another shows up 6+ times → clearly off.
Keep in mind: Small samples naturally vary. 50 rolls is just a first pass. For real rigor, you'd want 200+ rolls. This method works best for comparing two dice — if one die gives way stranger results than the other, that die may be biased.
Advanced Testing Methods
If you seek more rigorous and precise test results, or if you are a dice manufacturer or seller looking to conduct quality control on your dice, the following methods will be more reliable.
1. Static Balance Table
Use a precision level combined with a lowfriction pivot. Place the die on top and watch to see if it slowly rolls toward one side. This is a common spotcheck method used by professional game stores.
2. Chi-Square Test
This is the statistical “truth mirror.” Roll your D20 200 times, record how many times each face appears, then run a chisquare calculation. If the pvalue is less than 0.05, the die’s randomness is significantly off from the ideal distribution.
3. Industrial CT or Ultrasound (Extreme Cases)
You’ll only need this if you suspect a very expensive handmade die has hidden internal damage. It can reveal bubbles, cracks, or density layers. Most players will never go here — but it’s cool to know it exists.
What to do if you discover a bias?
If your dice are diagnosed as biased, you have a few options depending on the severity:
Mild bias:
Perfect for casual games. You can even use it as a "story dice"—specifically for when a character is having a bad day, adding comedic effect.
Severe bias (multiple salt water tests all point to the same side):
If you just bought it, contact the seller. Reputable stores usually offer returns and exchanges.
If you simply like the dice's appearance, besides putting it in your "dice prison," you can also keep it as a collectible or decorative item.
Remember: Random ≠ Average distribution. Occasionally getting two 1s in a row is normal. Only when there is a significant deviation in long-term statistics should you be suspicious.
Conclusion
A fair die won't make you stronger, nor will it change your fate. It only does one thing: leave the outcome to destiny. And the true joy of role-playing games comes precisely from the capriciousness of fate—the ecstasy of great success, the lament of great failure, and all the unexpected twists and turns.
If your die is biased, it's actually "choosing" the outcome for you, not letting the god of dice decide. What's the point then?
So, take 10 minutes to check your die. If you find it "cheating," either replace it or give it a "suitable seat."
📖Read More: