Is there a mechanical benefit to using a light crossbow over a long bow or short bow?

Question

A longbow (1d8, 150/600 range), and a shortbow (1d6, 80/320 range) benefit from "Extra Attack".

A light crossbow (1d8, 80/320 range), or a hand crossbow (1d6, 30/120 range), do not benefit from "Extra Attack".

A light crossbow is worse in terms of range, and damage (with Extra Attack) than the longbow. A light crossbow is on par for range with the shortbow, and worse for damage (with Extra Attack).

I understand that with Crossbow Expert Feat, you can make 3 attacks with hand crossbows at still a very short range of 30 feet.

---

Mechanically, I don't see any benefit to a light crossbow if you have an Extra Attack. Is there some benefit to using a light crossbow I am missing?

Answer 1

Lack of martial weapon proficiency

Just by their stats, a longbow does seem strictly better than a light crossbow.

However, longbows are martial weapons, and light crossbows are simple weapons. (PHB, p. 149)

As a result, some classes/races will not be able to use longbows effectively due to their lack of proficiency with martial weapons - in particular classes without Extra Attack often lack martial weapon proficiency.

As an example, a Human Rogue cannot wield a longbow with proficiency (barring feats). For this character, a light crossbow is one damage die better than a shortbow (which is also a simple weapon). Since they are a Rogue, they do not get Extra Attack, and so the fact that the shortbow can benefit from Extra Attack while the crossbow cannot (Loading property) does not come into play.

It's worth noting that a character who does have martial weapon proficiencies will likely be choosing between a heavy crossbow (which does more damage per attack) and a longbow (which works with Extra attack).

Underwater combat

Crossbows are better weapons than longbows underwater, due to their lack of disadvantage.

From the rules on underwater combat (PHB p.198):

A ranged weapon attack automatically misses a target beyond the weapon’s normal range. Even against a target within normal range, the attack roll has disadvantage unless the weapon is a crossbow, a net, or a weapon that is thrown like a javelin (including a spear, trident, or dart).

Small characters

Longbows and heavy crossbows both possess the Heavy property:

Small creatures have disadvantage on Attack rolls with heavy Weapons. A heavy weapon’s size and bulk make it too large for a Small creature to use effectively.

As a result, small characters will not want to use this kind of weapon, and would choose a shortbow or light crossbow (depending on their class, as above) instead.

Answer 2

Long Bows are Martial Weapons, and so require Martial Weapon proficiency. Light Crossbows are Simple Weapons, and so more classes have access to them. If you have access to both, then you normally also have access to the Heavy Crossbow, which deals D10 damage.

The classes who have access to only the light crossbow generally don't get Extra Attack (eg Warlock, Rogue, Wizard), so the downside doesn't manifest.

Answer 3

There are a lot of specific mechanical advantages, and a handful of less concrete potential advantages:

Crossbows do more damage than equivalent bows.

The correct comparison here is a shortbow to a light crossbow and a longbow to a heavy crossbow, because then you're comparing stuff with equivalent proficiency requirements (you can't get a longbow or heavy crossbow if you're only proficient with simple weapons, and there's no reason to chose a simple weapon if you're proficient with martial weapons). The crossbow does better damage in both cases, at the cost of weighing more and only being able to make one attack per turn without taking a specific feat. The heavy crossbow additionally has a shorter range than it's equivalent bow.

This leads to a rather easy set of decisions to decide on what ranged weapon to pick:

• If you're pure STR based for combat, you pick javelins (because they actually let you use STR due to being thrown weapons not ranged weapons).
• If you only have simple weapon proficiency, you probably don't get Extra Attack, and therefore the crossbow is worth taking if you need damage and can tolerate the other implications of the Loading property (and if not, you grab a shortbow).
• If you have martial weapon proficiency and you get Extra Attack and are a primary ranged focus, you pick a longbow.
• If you have martial weapon proficiency and do not get Extra Attack or aren't a primary ranged focus, you pick a heavy or hand crossbow depending on whether you want a free hand or not.

Crossbows work better than bows underwater

Bows have disadvantage underwater, crossbows do not (and this is actually more realistic than it sounds). So if you're paying a campaign with lots of sailing or something similar, crossbows are a better choice than bows.

Hand Crossbows are light one-handed weapons

This has a few implications that make the hand crossbow special. In particular:

• You can dual-wield hand crossbows if you want to, or you can wield a melee weapon and a hand crossbow.
• Bards can use a hand crossbow as a ranged weapon and still keep a hand free for spellcasting (or playing music). In theory so can paladins and rangers, but they have better options.

Additionally, there may be some less tangible RP related benefits to one or the other

This gets into GM specific territory, but one weapon or the other may have implications for social interactions, certain weapons may be easier to conceal (most GMs I know give you a penalty for trying to conceal a longbow or heavy crossbow because they're rather large), and some may be easier to find depending on where you are.