You’re sitting at a table, character sheet in hand, and the DM looks you dead in the eye. They ask for a roll that doesn't fit the standard plastic heap in your dice bag. Maybe you're playing a niche indie RPG, or perhaps you're just trying to divide a loot pile five ways. You need to roll a 5 sided die, but your hand keeps brushing against d6s and d20s. It’s a weird spot to be in. Honestly, the d5 is the black sheep of the polyhedral family. It’s not one of the "Platonic solids," those perfect geometric shapes like the cube or the tetrahedron. Because of that, most people think they’re stuck using a digital generator or just guessing.
They aren't.
Geometry is a bit of a jerk when it comes to five-sided objects. If you want a fair roll, you can't just shave a side off a wooden block and hope for the best. True randomness requires every face to have an equal surface area and an equal relationship to the center of gravity. When you roll a 5 sided die, you’re fighting against the laws of physics unless you have a very specific type of specialized gear—or a bit of clever math.
The Physical D5: A Geometric Oddity
If you actually go out and buy a physical d5, you’ll notice it looks like a weird, elongated prism or a spinning top. It's usually a "pentagonal dipyramid" that’s been truncated. Louis Zocchi, the famous dice designer behind GameScience, spent years obsessing over how to make non-standard dice roll fairly. His d5s aren't your typical spheres or cubes; they’re more like thickened triangles with rounded ends so they can’t land on a "dead" side.
Most of these physical d5s are "rolling poles." Think of a cylinder with five flat faces. You don't roll it like a ball; you flick it so it spins on its long axis. It’s satisfying, sure, but it feels different. It’s clunky. If you’re a purist who likes the "thud" of a d20, the d5 feels like a compromise. Some boutique shops like Koplow Games or The Dice Shop Online sell them, but they’re rarely in your local game store’s bargain bin.
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Why does this matter? Because weight distribution is everything. In 2012, researchers at various labs actually studied how the shape of a die affects its "fairness" or Newtonian randomness. If a side is even a fraction of a millimeter larger, the probability shifts. When you roll a 5 sided die that was 3D printed at home, you’re almost certainly getting a biased result.
Hacking Your Dice Bag: The d10 Method
You probably already have a d10. Most players do. It’s the easiest way to simulate a d5 without buying anything new. This is the "Divide by Two" trick, and it’s mathematically flawless as long as your d10 is balanced.
Basically, you roll your d10 and treat the results as follows:
- Roll a 1 or 2: Result is 1.
- Roll a 3 or 4: Result is 2.
- Roll a 5 or 6: Result is 3.
- Roll a 7 or 8: Result is 4.
- Roll a 9 or 10: Result is 5.
It’s simple. It works. It keeps the game moving. You aren't changing the probability; you're just remapping the outcomes. Since a d10 has two sets of five faces, you're just collapsing those two sets into one.
Some people prefer the "Subtraction" method. If you roll a 1-5, that’s your number. If you roll a 6-10, you subtract five. So, a 7 becomes a 2, and a 10 becomes a 5. It’s the same result, just a different mental path. I’ve seen players get into heated debates over which way is faster. Personally? Just divide by two and round up. It’s faster.
The D6 Reroll (The Lazy Way)
What if you only have a standard six-sided die? You can still roll a 5 sided die with it. You just have to accept that you'll be rerolling occasionally. You treat 1 through 5 as they are. If you hit a 6, you pick it up and throw it again.
Statistically, this is still perfectly fair. The probability of landing any number 1-5 remains exactly 20%. The only downside is the "dead roll" where you hit that 6 and everyone has to wait three seconds for you to try again. It kills the tension in a high-stakes moment. Imagine a dragon breathing fire and you’re stuck rerolling a 6 three times in a row. It’s a vibe killer.
Why Five Sides Anyway?
You might wonder why a game designer would even ask you to roll a 5 sided die. It’s usually about granular progression. In systems like Dungeon Crawl Classics (DCC), they use something called the "Dice Chain." Instead of just jumping from a d4 to a d6, they want a smoother curve. The d5 sits right in that sweet spot. It’s better than a d4 but not quite as powerful as a d6.
It’s also used in:
- Random loot tables where there are exactly five tiers of rarity.
- Determining days of the week in a fictional world with a shorter calendar.
- Specific "usage die" mechanics where your torch or rations slowly degrade.
In DCC, the d5 is part of the "funky dice" set, alongside the d7, d14, and d16. These dice force players to step outside their comfort zone. They break the monotony of the standard d20 system. Using a d5 feels intentional. It says, "The world isn't built on base-six or base-ten logic."
Digital vs. Physical Randomness
If you're playing online via Roll20, Foundry VTT, or even just typing "roll a d5" into Google, you're using a Pseudo-Random Number Generator (PRNG). These are algorithms. They use a "seed" (like the current time in milliseconds) and run it through a complex math formula to spit out a number.
For 99% of people, this is fine.
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But for the math nerds, it’s never "truly" random. True randomness usually requires atmospheric noise or radioactive decay. But let’s be real: you’re just trying to see if your rogue finds a hidden pouch of gold. A Google search is plenty random. The benefit of digital is that it removes human error—no cocked dice, no "did that hit the floor?", no biased plastic.
How to Spot a Bad D5
If you do buy a physical one, check the edges. Cheap injection-molded dice often have "sprues"—little bits of extra plastic left over from the mold. If a d5 has a sprue on the "3" side, it’s going to be heavier on that side. It’ll roll "3" less often.
Try the salt water test. Get a glass of warm water, dissolve a ton of salt in it until the water is dense, and drop the die in. If it floats, poke it. If it always rotates so the same number faces up, your die is unbalanced. Toss it. Or, keep it for when you're the DM and you want to mess with your players (don't actually do that, it's mean).
Practical Ways to Generate a 1-5 Result
If you're in a pinch and need to roll a 5 sided die right now, here are the quickest fixes sorted by "Least Annoying" to "Most Annoying":
- The D10 Mapping: Roll a d10, 1-2=1, 3-4=2, etc. This is the gold standard.
- The D20 Mapping: Roll a d20. 1-4=1, 5-8=2, 9-12=3, 13-16=4, 17-20=5. This is actually very smooth because the math is so clean.
- The Deck of Cards: Take an Ace, 2, 3, 4, and 5 from a deck. Shuffle and pull one. This is actually more "fair" than rolling if you don't reshuffle every time (it's called sampling without replacement), but for a single roll, it’s perfect.
- The Phone App: Every smartphone has a voice assistant. "Hey Siri, roll a 5 sided die." It works. It’s boring, but it works.
- The Hand Sign: Rock-paper-scissors is basically a d3. There are expanded versions (like Rock-Paper-Scissors-Lizard-Spock) that function as a d5. If you and a friend both throw at the same time, you can use a lookup table, but that’s way too much work for a game of D&D.
Actionable Next Steps
Stop worrying about not having the "correct" plastic. If you need a d5, grab a d10. It is the most efficient, mathematically sound way to keep your game moving without breaking the bank or waiting for a specialty shipment from an online hobby store.
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If you're a collector, go ahead and buy a specialized d5 from a brand like GameScience or Impact! Miniatures. They look cool, they’re great conversation starters, and they feel unique in the hand. Just make sure you aren't using a d5 that's just a d10 with duplicate numbers—unless you like the look of it.
The next time your gaming group hit a snag because someone needs a 1-5 result, don't stall. Use the d10 division method. It’s fast, it’s fair, and it makes you look like the smartest person at the table. Just remember: in the world of dice, geometry is just a suggestion if you know how to handle the math.
Quick Checklist for Fair D5 Results:
- Check your d10 for air bubbles if it's translucent.
- Ensure your "division" rule is decided before you roll to avoid cheating.
- If using a reroll method (d6 minus the 6), keep the die in a tray so it doesn't fly off the table during the extra tosses.
- When using digital rollers, stick to reputable sites like random.org which use atmospheric noise for higher quality entropy.
That’s basically it. No more excuses for stalling the session. Roll the plastic, get the number, and get back to the story.