As this post on RPG StackExchange states, pg 83 of the DMG says that the ideal party size is 3-5 players. This is also referenced in the official adventure modules written by Wizards of the Coast which are typically geared towards 4-5 or 4-6 players.
I can confirm this anecdotally as I’ve ran games for the ideal party size of 3-5 players, games consisting of over 6 players, and games with 2 or fewer players. The benefits of having only 3-5 players are huge. Having fewer players is not as much of an issue as having over 6 players for a multitude of reasons that I’ll explain later in this post.
It’s not impossible to run a game outside the ideal party size of 3-5 players, however you will be doing a lot more work as a DM in terms of preparation and running the game. These issues also apply more to a long-term campaign. If you’re playing a quick one-shot adventure things may be frustrating, but if it’s a short-term issue it’s manageable.
The Ideal Party Size
The biggest benefit that the ideal party size of 3-5 players has going for it is that the game is balanced with this group size in mind. You can take things more at face-value and won’t have to tweak as much of the source material to make everything work well. There are also mechanical and role-playing benefits for having 3-5 players as opposed to fewer or more players.
Everyone Has a Niche
I’ve written about how party composition should be determined in D&D in a previous post. It boils-down to choosing a role and building your character in a way that helps you fulfill that role. The smaller the group size, the less likely these roles will overlap. This means that you have a larger, more unique contribution to the group.
Each character has a chance to shine in different parts of the game. They can all complete something that the others cannot and it makes them more of an individual. Everyone gets a moment where the other players and characters think that they can do something amazing that they themselves cannot. This is healthy for the game as a whole.
Your party will have to make a conscious decision to avoid having a character that encompasses one of the main roles in D&D. The party will also have to decide to make characters that complete the same role. By this logic, if you and your group plan accordingly you’re most likely going to be able to create a character that brings unique powers and benefits to the party.
Optimal for Balance and Encounter Design
As I said before, D&D 5e was made with groups of 3-5 players in mind. A lot of the official adventures and materials can work with up to 6 players, but anything past that becomes hard to balance in the system.
The DM will have to do a bit of trial-and-error to learn how to create balanced encounters for groups outside of the ideal party size. Magical items also become an issue as having more magical items in a party can also trivialize fights. More people means more magical items, or at least more opportunities to use the items.
You can actually see proof of this by going to Kobold Fight Club and make an encounter with different combinations of players. 3-5 players are all challenged by roughly the same amount of creatures in an encounter. Outside of that sweet spot of 3-5 players you will have to adjust the number or difficulty of creatures in an encounter to properly balance it.
The jump from 5-6 is also not particularly drastic, but past this point you run into many different issues that I’ll touch on later.
Individual Character Development
Since each character has a well-defined role or niche in the party they have more chances to develop their character. An example of this is asking yourself “What does being the front-line tank mean to your character?” Perhaps your character wants to keep their friends safe, or they’re guilty about not acting fast enough to take the hit for a friend in the past. Having a role or niche is healthy for your game and gives you a chance to explore why your character gravitated towards that role.
You’ll also have more time and better quality role-playing with fewer people. When you interact with NPCs there are only a maximum of 3-5 of you there. Everyone has a chance to chime into the conversation without it being too long or boring for the rest of the group.
In a group of 7 people allowing everyone to make a point in a conversation would feel unnatural. That’s a formal meeting, not a casual encounter.
Issues with 6+ Players
I’ve written a post before on some of my tips for running a game with a larger-than-average party. This campaign lasted for just under a year, and by the end of it I was pretty burned out. It was a lot of extra work and as I said before, it all spawned from me not wanting to turn anyone away from the game. They’re all my friends and I would feel bad about excluding them from playing together with me. Here are some of the main issues I had with running a game with 9 players:
I’ve talked about the action economy of D&D 5e in a previous post, but it is also one of the major reasons that running a game with over 6 players becomes difficult. In that post I stated that players each have roughly 3-5 different actions they can take in a single round of combat. Each of these different decisions takes time to decide on and then enact. Let’s be extremely conservative and assume that it takes a player about 1 minute to complete their turn.
On average, combat should be around 2-4 rounds total. If you have 7 players that’s 7 minutes per round which is a total of 21 minutes if we assume combat is completed in 3 rounds. This is prior to adding in all the time it will take for the DM to complete each creature’s combat turn. Plus, with more players comes more complex or a higher quantity of creatures, further extending the amount of time needed to run a combat encounter.
This only gets worse the more powerful your party gets. The more spells and abilities a player has to choose from, the longer it may take them to take their turn. This is why one of my biggest piece of advice for running D&D for a larger-than ideal sized party is to force players to know what they’re doing as soon as their turn begins.
Look at Critical Role for evidence of this. They usually only run 1 big encounter per episode and it takes up a solid chunk each episode. They may pepper in smaller encounters, but even those will take a solid 10-20 minutes. This is a show with excellent players and a fantastic DM so it’s not an issue with them by any means, it’s simply how the game is designed!
This is the antithesis to one of my arguments for having the ideal party size of 3-5 players so that each character has a niche or a role to offer to the group. There are only 12 official classes in D&D 5e. Many of these classes can or do encompass the same role as another class. Having fewer people in the party means that each individual character is more likely to focus on a unique aspect of the game.
If you have 7+ players in your party there’s a good chance you’ll have multiple arcane magic users. While you can certainly carve out a small niche based on your archetype and spell choices, you’ll effectively have the same role as the other magic users in your party. Warlocks and sorcerers play very differently, but they generally have the same role of damage dealing and providing utility.
It’s difficult to have more individualized role-playing with a larger-than ideal sized party. Part of this is because of the fact that you have more players and therefore more voices that want to be heard. This in turn means that there are more voices that are also neglected during each role-playing opportunity.
Time is also an issue with role-playing. It becomes harder to let the group loose in a town or city since they can split up into a ton of smaller groups or walk around as individuals. This is a nightmare to try to DM while still giving your players a chance to have the spotlight. It’s also difficult to keep track of who is doing what as the DM since you have to keep track of so many different things.
This is perhaps one of the biggest issues with having a large amount of players. Your entire group is going to have to settle on a time to meet and play for a few hours every so often. Having more people means having more unique schedules to sync up. This gets more difficult as everyone takes more responsibilities on at home, at work, and elsewhere in their lives.
If you play in-person this adds another layer of complexity to logistical planning. You now need a space that will fit 7+ people regularly for a few hours a week. This place will also have to be within a reasonable distance for all of your players.
Issues with 2 or Fewer Players
A game that consists of 1 or 2 players will be much harder to run and will run into some unique issues. There are plenty of ways to homebrew around these issues, but they are still worth mentioning.
Combat is More Dangerous
It does become much harder to balance combat for fewer players. Overall this can make it more dangerous or less of a challenge depending on how experienced you are at balancing combat encounters. Just like with a group of 6+ players you will eventually get used to balancing encounters for them.
One glaring issue though is for characters that are downed. In a party of 3-5 players you have 2-4 other people who can try to stabilize you. In a smaller party you may have 1 other that can do this, or if you’re by yourself you’re in trouble. The stakes are much higher and the party will have to make tough decisions and play more cautiously to compensate for this.
One benefit with a smaller number of players is that combat is actually a lot quicker. This allows you to fit more encounters in per session, or focus more on role-playing or other aspects of the game. All of this does require a bit of extra prep time since more content means more time spent making that content between sessions.
Difficult to Use Premade Materials
As I mentioned earlier, most of the adventures from Wizards of the Coast and otherwise seem to target 4-6 players. Homebrew adventures tend to keep to the range of 3-6 players as well. You’ll severely limit your options if you are running with a party that has fewer players than the ideal party size of 3-5.
This is not something that will be detrimental to every group. If you are keen on homebrewing your own game already this barely affects you. However, if you like to run modules or lean on adventures you’ll need to do a bit of extra review and revision so that they’ll work well with your group.
There certainly are materials out there that are balanced for 2 or fewer players, but they’re less frequent than your other options. Most of the time though, the point still stands that it requires a bit more work and prep time on the DM’s end for premade materials to work properly with a small group.
Uneven Party Composition
This is basically the opposite issue of having too many players. While each of your characters will have a clearly defined niche and role, there will definitely be something missing in the group. If you have a wizard, a fighter, and a cleric you have a pretty well-balanced party. However, you still lack a proper charismatic character or a stealthier character.
5e is excellent about having backgrounds and feats that can aid a character to pick up parts of these roles. Regardless, your group will still lack bits and pieces of these missing roles. This is not always a bad thing as it does force the party to use creativity to bypass these obstacles.
While it’s certainly possible to play D&D 5e with more people than the ideal party size I’m not sure I’d recommend it, especially for a long-term campaign. Combat becomes sluggish even when people are on their A-game due to the action economy. Another issues is that everyone’s niche overlaps so it’s hard to “shine” when there’s 1 or 2 other people who can do the same job.
D&D also becomes more of a wargame than a role-playing game since it’s hard to have solid role-playing when there are that many people present. I feel that there are probably better systems out there that can streamline these issues way better than D&D 5e.
If the group has too many players the DM should attempt to split them into two separate groups. Even if you have to play with each group less frequently, it’s more worthwhile to everyone to play less frequently but have a better quality experience.
After running my 9 player game I have stuck to the ideal group size of 3-5 players and consequentially, I’ve enjoyed D&D 5e a lot more. It’s definitely the ideal party size and I find that the sweet spot is even closer to 4-5 than it is to 3-5. At this point I’ve set a hard-limit of 6 players as after that the game becomes both sluggish and much more work for me as a DM. It’s hard to turn people away from a game, but it’s not worthwhile for me to break this rule.
Personally I reserve games with 1-2 players for one-shots or special occasions. They’re fun, but not really my style for a long-term game.