# How can I fairly adjudicate the effects of height differences on ranged attacks?

My group is starting a sea-based campaign, and the gunslinger character (Matt Mercer's third-party fighter subclass) is asking about how being in the crow's nest will affect his range.

Since he will be targeting creatures significantly below him (about 110 feet down) that are only 25 feet horizontally from his position, he is asking how he should adjudicate weapon range.

How can I fairly adjudicate the effects of such height differences on ranged attacks?

• Is this game using a grid? Commented Apr 29, 2019 at 17:40
• Yes we are. I even have the boat and masts set at 5' square intervals. Commented Apr 29, 2019 at 18:24
• Are you using a paper or hand-drawn grid, or an digital grid, such as Roll20?
– Jack
Commented Apr 29, 2019 at 21:49
• Are you asking a geometry question related to calculating range at a non-right angle, or are you trying to determine if your player's attack should have longer range when shooting downward? Commented Apr 30, 2019 at 0:05
• Paper grid essentially (square battle mat). Commented Apr 30, 2019 at 15:02

# Either use the simplified PHB rules or do the real math

There isn't necessarily a 'right' way here, but you do have to account for the height as part of their distance because that is how far the target is from the archer.

## The quick and dirty

This is done by utilizing the Grid Variant option found in the PHB on page 192:

To determine the range on a grid between two things—whether creatures or objects— start counting squares from a square adjacent to one of them and stop counting in the space of the other one. Count by the shortest route.

This doesn't make any real world sense, but in the base system, there is no difference between a target 110' directly below and one 30' away as well. They're both considered 110' away.

But it's easy. If you're looking for true distance, then you've got some math to do.

## Pythagorean Theorem to find true distance

Or you can call Pythagoras and use his theorem (A2+ B2 = C2) to get a more exact value. In this case A would be the mast height, B the horizontal distance from base of mast, and C is the hypotenuse for true distance.

The true distance would be 112 feet based on the hypotenuse length. The Theorem system matches that optional grid variant rules in the PHB (pp 192):

## DMG Offers an other Variant:Diagonals option (pp252)

When measuring range or moving diagonally on a grid, the first diagonal square counts as 5 feet, but the second diagonal square counts as 10 feet. This pattern of 5 feet and then 10 feet continues whenever you’re counting diagonally, even if you move horizontally or vertically between different bits of diagonal movement. For example, a character might move one square diagonally (5 feet), then three squares straight (15 feet), and then another square diagonally (10 feet) for a total movement of 30 feet.

Carcer actually has simplified how this would work and is a great suggestion for getting something more realistic and getting it quickly:

The distance according to the variant diagonals rule can be very quickly calculated by taking the longer of the horizontal or vertical distance and adding half of the shorter distance, rounding down to the nearest 5ft multiple - e.g. a target 110 ft. down and 25 ft. away (or 110ft. away and 25ft. down) is 110 + 12.5 ~= 120 ft. distant.

## Be aware of other issues - and be consistent with whatever you choose

The DM may also want to consider the use of partial cover as the archer has to shoot through the rigging around the mast - but that's up to the DM.

Motion of the ocean may be another issue to consider. The potential rolling seas as well as the crows having a much stronger motion feeling due to it's height may impose disadvantage on the shot should the DM think it was worth doing so.

Also be aware of any darkvision distance issues if fighting at night.

Whichever method you choose, I do recommend that you use the same methodology in all cases whether PC or NPC. Make the rule known and agreed upon so that the players understand the implications.

• I would actually promote advantage instead of disadvantage; historically having the high ground has been beneficial, and it adds a layer of positive tactical thinking (Gaining advantage is always better than doing something fancy such as getting in the crows nest only to be told 'haha disadvantage!') Commented Apr 30, 2019 at 11:44

Even though it's extremely common to do so, 5th edition assumes you are not playing on a grid, by default. Using a grid is proposed on PHB 192 as a variant rule. In that rule, it says that moving to any adjacent square (including diagonals) counts as 5 feet, period:

Entering a Square. To enter a square, you must have at least 1 square of movement left, even if the square is diagonally adjacent to the square you're in. (The rule for diagonal movement sacrifices realism for the sake of smooth play. The Dungeon Master's Guide provides guidance on using a more realistic approach.)

This means, regardless of actual math, that we can measure your distance traveled as two straight lines, distance forward, and to the side. Whichever of this is longest will be the equivalent of how far you've moved.

You would measure other distances the same way, like how far away a flying creature is, or how far we need to shoot downward at a target.

A simple example of this is if I move forward 10 feet and to the side 5 ft (2 squares by 1 square), I've moved 10 feet.

So for your example, if he is 110 feet up, but only 25 feet away horizontally, the distance would be measured as 110 feet.

This is used for simplicity's sake but is not mathematically accurate. Aware of this, the designers proposed an alternate method in DMG 252 (as mentioned above):

### Optional Rule: Diagonals

The Player's Handbook presents a simple method for counting movement and measuring range on a grid: count every square as 5 feet, even if you’re moving diagonally. Though this is fast in play, it breaks the laws of geometry and is inaccurate over long distances. This optional rule provides more realism, but it requires more effort during combat.

When measuring range or moving diagonally on a grid, the first diagonal square counts as 5 feet, but the second diagonal square counts as 10 feet. This pattern of 5 feet and then 10 feet continues whenever you're counting diagonally, even if you move horizontally or vertically between different bits of diagonal movement. For example, a character might move one square diagonally (5 feet), then three squares straight (15 feet), and then another square diagonally (10 feet) for a total movement of 30 feet.

If you aren't using the Grid variant rule, you would just measure the distance from point A to B.

You can also, of course, actually do the math as NautArch suggested in his answer. It comes down to what you and your players can agree on. But either way, whatever rules you set for measuring diagonals should be used for all cases of measuring diagonals. As long as you're consistent within your own game, that's what matters.

• The hypotenuse is the longest side of a right triangle. Your answer is inconsistent. Commented Apr 29, 2019 at 17:00
• Commented Apr 29, 2019 at 17:45

There is no solid right way to do this, but here are three ways this can be adjudicated.

# Pythagoras

Using the Pythagoran theorem of $$\a^2+b^2=c^2\$$ you would obtain a distance of 112.8 ft. This is the most accurate method, but is going to necessitate calculations, and your mileage may vary but I prefer not to large squares and roots in my head and having to resort to a calculator all the time might slow your game down.

# Simple sum

If you just add the distances together (giving 135 ft) you can very quickly estimate an upper bound for the distance. This can be very useful because if that estimate puts it in range then it is going to be and more accurate calculations need not be performed.

# Adapt the Optional Diagonal Rules for playing on a grid

In the optional rules1 presented on page 252 of the Dungeon Master's Guide every other diagonal move in a 5 ft by 5 ft grid costs 5 extra feet of movement where a normal diagonal costs 5 feet. You could then move diagonals counting 5 feet per and add an extra 5 for every other moved. However to make it simpler we can observe that a move 10 ft vertically and 10 ft horizontally would cost 15 feet when moved diagonally. A resultant rule to estimate a angular distance is that for every 10 ft moved both diagonally and vertically, 5 feet is subtracted from the summed distance.

With our specific example the vertical distance is 110 ft and the horizontal is 25 ft. The summed distance is 135 ft, but there is 2 '10-feet' moved by both so 2$$\\times\$$5 feet is subtracted. The estimated distance is then 125 ft. (The number of '10-feet's would be equal to the smallest of the distances divided by 10 and rounded down.)

This is between the two other estimates and has the advantage of being fairly quick to calculate (much more mental-arithmetic friendly than Pythagoras) and consistent with other movement (if you're playing on a grid).

1: It is an optional rule for the variant rules presented on the sidebar on page 192 of the Player's Handbook.

This GM always uses the following houserule:

Vertical distance doesn't affect the higher shooter, whilst it is added to the horizontal distance for the lower shooter

Thus your character in the crows nest will be able to shoot at the creatures as if they were 25' away, whilst those on the ship shooting at him have to do so as if they were 135' away.

This gives the higher combatant an advantage, as shooting up is always harder than shooting down, whilst it avoids any complexity from trigonometry or the diagonal rule.

• Doesn't his give a HUGE advantage to ranged flying combatants? Commented Apr 29, 2019 at 18:00
• I've not had to deal with ranged flying combatants that I've not been controlling myself, so I've not hit any issues. My gut says any vertical distance at or beyond long range would apply disadvantage, but I'd want to playtest it to be sure. Commented Apr 29, 2019 at 18:08
• Having the high ground IS a huge advantage but in some cases this can give a lot more advantage than it should. Using your house rule as stated, I have the same chance of hitting no matter how far I am above me targets? 20 feet up is the same as 100 feet up is the same as 10,000 feet up? So long as the horizontal distance is significantly greater than the vertical distance, i.e. if I am 100 feet away and 30 feet higher, then this rule is fast, easy and close enough to accurate. But as the angles get steeper this rule begins to fail IMO.
– krb
Commented Apr 29, 2019 at 19:11

The shorthand for determining distance is in the PHB 192, "Variant: Playing on a Grid":

To determine range on a grid between two things - whether creatures or objects - start counting squares from a square adjacent to one of them and stop counting the the space of the other one. Count by the shortest route.

Because of the 3-dimensional nature of being above them, if you wanted to do the Variant RAW then it would most likely be be the squares of space down the mast (22 squares for 110ft), and then up to 5 squares for the remaining 25', since the first 5' of that would be the adjacent square you begin counting from, making the range anywhere from 115' to 135' in the basic rules.

Personally, I'd recommend going for NautArch's Pythagorean approach and incur half-cover to both the gunslinger and the targets for realism and to not have your player have a "fish-in-a-barrel" scenario of free shots to anybody not coming to a sea fight with bows.

• Thank you for your contribution, but answers are not the place for comments. When you earn enough reputation you will unlock the ability to comment. Commented Apr 29, 2019 at 17:31
• Yeah, that's why I tried to put as much information in as I could to make it more of an answer while addressing issues in previously proposed answers. Sorry if that's incorrect form or violated rules. Commented Apr 29, 2019 at 17:37
• I see! Well I've removed the comment language to make you intentions clearer! I think making the answer was the right thing to do, but in the future possibly just don't start it with "I can't comment but...". Anyways welcome to RPG.se! And sorry for the rough start, but I actually do think you have the basis for a solid answer here with that edit made. Commented Apr 29, 2019 at 17:40
• Okay, thanks! I'll keep it in mind for the future Commented Apr 29, 2019 at 17:51