# Rolling a D10 (0-9) for hitpoints. What do I get with a zero?

My character leveled up and I rolled a D10 to determine the rise in hitpoints. The dice that I used goes from 0 to 9 and I rolled a zero. The DM told me that this means I only add my modifier (0 + 3 = 3).

I didn't agree with this and think it counts as 10. The 0 is probably there for cosmetic reasons.

Who is right in this situation?

• Commented Sep 2, 2018 at 14:05
• Does your DM always treat 10 as "0" for d10 (for damage, etc)? Or was it only about hit points? Commented Sep 2, 2018 at 14:27
• This is so weird to me. Logically, every other die starts at 1. d4, d6, d8, d12, d20. Why would the d10 be any different? Commented Aug 4, 2023 at 10:45

### A zero on a d10 counts as 10.

This isn't clearly specified in the 5th edition rules, but is clearer in earlier editions of the game, and widely understood among long-time RPG players. However, we can still surmise from the D&D 5th edition rules that d10 is 1-10 like all other dice, from the following:

• Hit Dice by Size (Monster Manual p.7) confirms that the average of 1d10 is 5½, which is consistent with a range of 1-10. (The average of 0-9 would be 4½.)
• The fighter receives 10 hit points at 1st level. This wouldn't make sense if a d10 couldn't actually reach 10. All other classes receive the highest value of their roll at 1st level (e.g. the monk receives 1d8 per level, and 8 at first level).
• The fighter may take 6 hit points instead of rolling 1d10. This is consistent with the average result of 1-10 (5.5) rounded up. All other classes work the same way (e.g. the monk can take 5 hit points, equivalent to the average of 1-8 (4.5) rounded up). But the average of 0-9 is 4.5, so if 1d10 really meant 0-9, we would not expect to see the fighter allowed to take 6.
• The D&D Beyond character builder can confirm that if you create a fighter above level 1 with rolled hit points, they can indeed gain a roll of 10 on their hit points.

The reason for the zero is that in many games including D&D, two d10s can be rolled together to generate a two-digit percentile number between 00 and 99. As per PHB p.6, "Two 0s represent 100," another precedent which suggests that zero on the dice doesn't necessarily mean zero.

• Nice proof you've collected here, but imho you should also point out the Defining Event table of the Folk Hero background (PHB, p. 131): It lists all the possible outcomes of the d10 from 1 to 10. Commented Sep 4, 2018 at 8:49
• It will always bug me that it's 00-99 instead of 01-100. Considering the 0 on a d10 being 10 by itself you would think rolling 00 would be 1-10, 10 would be 11-20... 90 would be 91-100. But nooooo, it magically turns into a 0. Commented Sep 5, 2018 at 15:54
• if it's 00, it's 1(00) Commented Aug 18, 2022 at 19:12

You are correct. Many old school d10s are marked 0-9 but you count the 0 as 10.

If he doesn’t listen to reason, next level use one of the d10s marked 00-90 instead and demand your 45 or so hit points from that roll.

• Let's make D6 and D10 dices with 99.'s on all sides.
– Cœur
Commented Sep 9, 2018 at 11:02

The Player's Handbook discusses dice on p. 6, in the subsection titled "Game Dice":

In these rules, the different dice are referred to by the letter d followed by the number of sides: d4, d6, d8, d10, d12, and d20. For instance, a d6 is a six-sided die (the typical cube that many games use).

Percentile dice, or d100, work a little differently. You generate a number between 1 and 100 by rolling two different ten-sided dice numbered from 0 to 9. One die (designated before you roll) gives the tens digit, and the other gives the ones digit. If you roll a 7 and a 1, for example, the number rolled is 71. Two 0s represent 100. Some ten-sided dice are numbered in tens (00, 10, 20, and so on), making it easier to distinguish the tens digit from the ones digit. In this case, a roll of 70 and 1 is 71, and 00 and 0 is 100.

It does not actually say that a d10 generates a number between 1 and 10, but that is how it is interpreted. The zero means 10.

• The 0 does mean ten on a d10, but percentile dice aren't a good way of showing it. If you roll e.g. 40 and 0, that 0 is zero.
– Ray
Commented Sep 6, 2018 at 1:30

## A 0 counts as a 10

The Player's Handbook talks about dice referring to each dX as a die with X sides implying that the number of sides is the maximum roll through context.

There is also some circumstantial evidence in the spell confusion, which states:

An affected target ... must roll a d10 at the start of each of its turns to determine its behavior for that turn.

$$\begin{array} {|c|l|} \hline 1 & \text{The creature uses all its movement to move in a random direction...} \\ \hline 2-6 & \text{The creature doesn't move or take actions...} \\ \hline 3-7 & \text{The creature uses its action to make a melee attack ... randomly} \\ \hline 9-10 & \text{The creature can act and move normally.} \\ \hline \end{array}$$

Since there is no 0 in the table but a 10 is included, the most reasonable assumption is that a 0 is a 10.

A d6 goes from 1 to 6. A d12 goes from 1 to 12. A d10 goes from 1 to 10. That zero is the ten.

And in case your GM starts wondering...

## Why is it a zero then?

While rarer in modern DnD, it's quite a common use of d10 to roll two at the same time to simulate a roll of d100. This is why these dice are often sold in sets with one die having "tens": 00, 10, 20 and so on, and the other having just "ones": 0, 1, 2, 3 and so on. One'd roll two dice and combine the tens and ones to get a result, eg. 80 and 7 yield an 87, with the special case of 00 and 0 typically but not universally meaning 100. Using d10's as d100 is the use where zero means a zero (except in the 00+0 case).

Even when intended for percentage rolls, the "ones" die could of course include a ten instead of a zero, at risk of being suspectible to be confused with the "tens" die (both'd have a 10), being somewhat uglier (at least to my taste) and causing a fair amount of "sixty, uh, tens" which might be jarring to those of us who aren't French. Indeed, d10s with numbers 1-10 do exist, they just don't seem to be as common.

When used as a single die, the aforementioned purpose of the 0 doesn't really exist, so a roll 0 on a d10 is a ten.

• Ah, how I love to work in a number-intensive role and knowing just enough french that people expect me to follow along as they read up 5 or 6-digit numbers. I hear somewhere between 8 and 19 digits. Quattre-vingt-seize - did you mean 96 and more numbers will follow or was that 802016? You guys... ;-) Commented Sep 4, 2018 at 7:26
• @zakinster Nay, 00+1 for instance is 1, not 101. Commented Sep 5, 2018 at 10:12
• @kviiri ah yes, didn't think this through, I'll delete my confusing comment. Commented Sep 5, 2018 at 11:32
• Also may be worth mentioning, all dice used single digits in the very early days of D&D. D20s were marked 0-9 twice, with one set inked in a different color. I assume there's some reason tied to how the dice were manufactured. Commented Sep 5, 2018 at 17:22