When we’re creating or using a creature in D&D 5e we’re generally not thinking much about a creature’s size besides how we’ll describe the creature to the players. However, even if we’re not actively considering it, a creature’s size has a noticeable impact on combat in quite a few different ways.
Map control is one of the most important tactical objectives in any given combat encounter. The side that has the most space under their control has potentially more favorable positioning options compared to their opponent.
Big creatures have an inherent advantage as they physically take up more space on the battlefield and therefore, control more of the battlefield by simply existing. If they’re able to use this size differential between themselves and the small/medium size party members then they can quite literally corner the party and pick them apart if the party isn’t careful.
So let’s talk about creature size today and how, in most situations, it is advantageous to the larger creature(s).
Creature Size Mechanics
|Size||Space||Number of 5ft. Squares||Hit Dice|
|Tiny||2 1/2 by 2 1/2 ft.||1/2 a square||1d4|
|Small||5 by 5 ft.||1 square||1d6|
|Medium||5 by 5 ft.||1 square||1d8|
|Large||10 by 10 ft.||4 squares||1d10|
|Huge||15 by 15 ft.||9 squares||1d12|
|Gargantuan||20 by 20 ft. or larger!||16 squares||1d20|
Here’s a table I made by using the size categories table on page 191 of the PHB as a guideline. I added a couple of columns to it based on my observations concerning creature size.
I included the 5 ft. square measurement as I always use 5ft. square battlemaps so it’s helpful for me to visualize creatures in that manner as opposed to saying “oh the creature is 8 ft. tall” or something of that nature.
A creature’s hit dice value is not always determined by its size, but it generally is. Check the creature’s statblock before you assume anything, but there’s an established pattern.
A Creature’s Combat Space
As I said before, the side that controls the largest or most beneficial portion of the battlefield is at an advantage in combat. Being physically larger than your opponent by an order of magnitude gives you an inherent advantage at being able to control the battlefield, simply because you take up more of it.
A creature’s size dictates how much space a creature can control in combat. So sure, a creature that’s 11 ft. tall and 5 ft. wide is considered a large creature, but they still take up a 10 ft. by 10 ft. space in combat due to their size.
Other creatures cannot enter a creature’s space in combat unless they have a trait or ability that specifically allows them to. This is what I mean by large creatures being at an advantage concerning battlefield control. They simply take up more space that the party can’t control!
Obstructing the Party’s Path
If a creature can fully obstruct an entrance or passageway then they are considered an obstacle that has to be actively dealt with. What this means is that the only way to get through a passageway that a large monster is blocking is to either move the creature yourself or slay it.
The cool thing about this tactic of blocking an entry point is that the blocker(s) can actively choose who they allow to pass by them. This means that a large creature can allow their small minions to flood the hallway the party is standing in while they slowly proceed behind them, preventing the party from entering the room they’re guarding.
Although, keep in mind that a tactically-minded party can use choke-points and bottlenecks to their advantage too!
One of the downsides to being larger than a hole, hallway, crawlspace, or any other area you have to squeeze through is that well, you have to squeeze!
Any creature can squeeze into a space that is one size category smaller than it. So, for example, a Huge creature can squeeze into a 10 ft. x 10 ft. hallway, but a Gargantuan creature couldn’t. Though to be fair, the Gargantuan creature would probably just knock the building down, but I digress.
When squeezing through a space, a creature expends an extra foot of movement for each foot they move. So essentially this space counts as difficult terrain. In addition to that, creatures have disadvantage when making attack rolls and Dexterity saving throws while they are squeezing and all attacks against them are made with advantage.
Forcing a creature or character to squeeze through a space can be a massive tactical win if you can pull it off in the right context!
Using a Creature’s Size to Your Advantage
A larger foe is indeed going to be much more intimidating and potentially more powerful. However, the bigger they are, the harder they fall!
Enormous creatures take up a huge portion of the battlefield. This is, of course, dangerous as you need to mind where you stand as they have a larger hitbox than a typical medium-sized creature. This means that larger creatures have a larger area that will trigger attacks of opportunity or just attacks in general.
However, this size is ultimately their downfall. It means that it is more difficult for these creatures to find cover large enough to protect them from the party’s ranged attacks.
A bigger hitbox also means that the melee combatants of the party have more opportunities to attack them. Melee units now have more options where they can stand and attack while positioning themselves further away from the rest of the enemy’s forces.
If you’re using the optional flanking rules then the party will have an increasing number of positions they can take to gain the benefits of flanking with larger enemies.
Sure, there are a few options that the party has to use a creature’s size against them, but as the DM you get a few toys to play with of your own when controlling big creatures!
The larger a creature is, the more of the battlefield they can control. This limits the amount of space and maneuverability the party has around the battlefield. In addition to that, the party also needs to be way more conscious about avoiding triggering opportunity attacks.
Many enormous creatures will have additional reach tacked on to some or all of their melee attacks as well. So that sizeable amount of real estate that the creatures already controls effectively becomes even larger with regards to opportunity attacks.
If the players aren’t mindful you can position an enormous creature in such a way that will cut off some party members from the rest of the group. This can be a very dangerous scenario to be in as it becomes increasingly difficult to aid the characters that are separated. What if reinforcements come? Those characters can quickly be in grave danger!
In addition to all of that, larger creatures typically can wield heavier, more powerful weapons, so keep that in mind as well.
Creature size is a “role-play first” part of a creature’s statblock. If you want a creature to be big you’re going to be thinking about it from an aesthetic point of view. However, there are plenty of ways that creature size impacts combat from a mechanical point of view.
Larger creatures typically have a larger hit die than their smaller counterparts. This is a sizeable boon since more HP is always a plus.
However, there are other aspects of a creature’s size that make it more difficult to crunch numbers to see the impact they have on combat. Factors such as a larger hitbox can be considered as both a boon and a bane for the creature.
A creature’s hitbox is just one kind of role-playing aspect that you as the DM or player need to keep in mind when engaging them in combat. No one wants to be hit by an ogre’s greatclub because they weren’t being careful when dashing around the battlefield!