Theoretically 5 per day, in practical play 3 per day
There are multiple was to derive an estimate for the number of encounters per day:
Calculated from the DMG: 5 per day
The DMG provides tables of expected experience per character and adventuring day on page 84, and of expected XP per Easy, Moderate, Hard or Deadly encounter on page 82. From this one can calculate the expected number of encounters of each type in a typical adventuring day, if one had only that difficulty of encounter.
The numbers vary slightly from level to level, but on average over 20 levels of play they come to
If all encounter difficulties were equally likely, that would mean on average 7 encounters per day.
There is a statement on page 84 DMG "Assuming typical adventuring conditions and average luck, most adventuring parties can handle about six to eight medium or hard encounters in a day.", slightly higher than these numbers, maybe because encounters are not supposed to go all the way to the point where the party cannot handle them any more.
Easy encounters are described as follows:
Easy. An easy encounter doesn't tax the characters' resources or put them in serious peril. They might lose a few hit points.
So, for the purposes of consuming limited use of daily abilities, we can ignore Easy encounters, as they are supposed to not tax the characters' resources, other then losing a few hits. This also matches my experience: for example, characters rarely waste their limited features on fights they know they can handle with cantrips and routine attacks. We will just average Medium, Hard and Deadly ones, assuming all types of encounter are equally likely.
With this, the average, "theoretical" number of resource-consuming encounters per day based on DMG guidance is 4.6. Rounding it to a full number, it's five encounters per day.
Calculated from Mines of Phandelver and actual play: 3 per day
Now, one counterpoint is that all encounter difficulties may not be equally likely in an actual game or campaign. And we cannot know how the distribution looks like for every game. However, we at least can know it for some of the published campaigns.
Technoskald took the effort to list every encounter in Mines of Phandelver with its difficulty ranking based on the characters' level at the time of the encounter. Over the course of that adventure this is the distribution of encounters:
That is 41 encounters total, and 33 of Moderate to Deadly difficulty.
Ignoring the Easy encounters again, due to the higher share of deadly encounters in the mix, the average from this published sample is slightly lower, and if you round it comes to four encounters per adventuring day.
However, this assumes that each day is fully filled with encounters, until the characters have exhausted all their resources. In my experience, in the absence of clear time pressure, players often opt to rest and recover before all of their resources are used up. You never know what's coming for you in the night. So, as long as the players have some ability to influence the number of encounters, you can expect it to be lower in the wild than what the XP guidance suggests.
This is borne out by practical experiment. We played LMoP, and even though our DM egged us on through NPCs to press forward whenever he could, we took in total 32 days of in-game time to get through it. There are many days of traveling around the countryside. At 33 resource-taxing encounters, that would just be one such encounter per day. However I think a better way to look at this is by looking at the days were we actually did have encounters.
If we remove all the "empty" days without combat encounters were we were just traveling or shopping or doing research, we had 11 days with encounters, or three encounters per day. Some of these were a single encounter when being ambushed traveling at night, others were dense with high numbers when fighting through one of the major adventure sites
like the goblin cave, manor or mines.
Player Surveys: 3 per day
ENWorld ran a survey asking players of 5e, "On average, how many combat encounters do you experience per day in a 5e game?". There were 82 answers:
|Less than 1
|7 or more
From this it is clear that nobody seems to be experiencing days with 13 Easy encounters, and two or three encounters per day are the most common. If we count "less than 1" as 1 and "7 or more" as 7, the average here is 3 encounters per day.
There is also this poll, better powered with 286 votes cast, that asked "The 5e DMG suggests 6 to 8 encounters per long rest with 2-3 encounters per short rest. I assume that this means that this is how they balance abilities that are on short rest and long rest cool downs. In practice, how many encounters on average do you have per long rest in your campaigns (as a DM or a Player)."
With a weighted average of pretty exactly 3 encounters per day (and even if the average of more than 8 was around 12, still would be only 3.2).
This matches our own game experience of three encounters per day. The explanations for the difference to the theoretical four or five are likely the same:
- very Easy encounters do not register as a challenge and cost no resources
- DMs try to present exciting and dangerous fights, which means Deadly encounters that you can only do three or so of per day
- and unless pressed for time, players will try to rest before being pushed to the limit, further undercutting the theoretical encounter numbers
For building a character for a real campaign, three resource consuming encounters per day seems to be the most useful assumption. Four or five encounters per day are also an OK assumption, based on the theoretical number of encounters.