What is the weapon damage range formula?

The short answer is that depending on the weapon, minimum damage that an ammo type can do is between 50-80% of its base damage, when hitting a target past its respective effective range.

This is a complex answer, so in order to gain a full understanding I suggest you play around with the spreadsheets involved yourself. This is accurate as of 8/9/2021.

From this excellent reddit post by user viddie- posted in r/playrust:

Damage drop-off in Rust is based on three components: The ammo used, the weapon used and the distance to the target. All ammo types have a certain minimum range up until which the damage is not reduced and a maximum range after which the damage is limited to a certain % value of the damage. The following table shows the base values for this:

Between the min and max range the damage drop-off is linear from 100% to the minimum damage of the ammo type. Each weapon can modify both the min and max range with a multiplier.

For example, the Python (9mm) has a multiplier of 80% making it's min range 8 meters and max range 48 meters.

The Crossbow (Arrows) on the other hand has a 150% multiplier to end up at min range 15 meters and max range 90 meters.

And here is a list of multipliers/ranges for all weapons:

Here is a link to an excel sheet with all of the relevant damage graphs.

In addition, fire damage adds another layer of complexity, as viddie- explains further:

Fire 9mm or 5.56 add 12% of the weapons damage additionally on top of the original damage of the weapon as fire damage. Fire damage ignores any and all armor, EXCEPT heavy armor to which just the fire damage is multiplied by 2. An example with the AK: 50 base damage + 12% = 50 base + 6 fire damage. Against someone in full metal armor on the upper body the damage would be: 50 * 0.45 + 6 = 28.5 damage.

The fire damage portion is susceptible to damage drop-off as well as the damage modifier of the body part (75% for legs, 200% [for all non-primitive weapons] for head). A few notable cut-offs for this:

• Below 26 meters the M249 can one-shot someone wearing a Coffee Can Helmet
• Bolt / L96 headshots on close range deal 99.2 damage to someone wearing a Facemask
• Below ~25 meters the AK can kill someone wearing the Heavy Plate Helmet in 3 shots

Both fire arrows and explosive ammo deal bonus damage in an area around the location that was shot. The bonus damage ignores both range and body part modifiers.

Fire arrows deal a flat 20 bonus damage, regardless of the bow used. This damage is unaffected by armor, except heavy armor to which is deals some kind of extra damage (couldn't figure this one out tho...). The downside of fire arrows however is that the arrow itself (not the bonus damage) deals 20% reduced damage compared to regular Wooden Arrows. This makes fire arrows best be used with a Bow (50 base - 20% => 40 base +20 flat) and the Compound Bow yields the worst results (100 base - 20% => 80 base + 20 flat). Of course the usefulness depends on the armor of the target, so if your enemies have a lot of armor fire arrows always deal quite a lot more damage, especially if you are shooting on a range that would typically feature a lot of damage drop-off.

Explosive ammo is somewhat similar to fire arrows, except they have a smaller blast radius and only add 5 flat damage. They do however not reduce the base damage of the 5.56 weapon but the bonus damage IS reduced by the explosion protection of the target (a full metal kit only has 8%).

Finally, the whole equation may be laid out as follows:

W * B * A * R

With

W = Weapon base damage

B = Body part modifier (75% Legs, 100% Upper Body, 150%/200% Head for Bows/Guns)

A = Armor modifier

R = Range modifier

R is calculated like this: 1 - ((D - MinR) * (C / (MaxR - MinR)) With

• D = Distance to target in meters

• MinR = The min drop-off range of the weapon as seen in the table above

• MaxR = The max drop-off range of the weapon

• C = Damage reduction cap of the weapon, e.g. "0.2" for all non-slug weapons

Additionally R is capped between 1 and (1 - C)

This is without any additional damage like fire ammo.

Source Spreadsheet