Ultima Online damage calculator: how a hit is worked out

For official shards · every figure sourced · updated with v35.213.2

Damage in UO is not one number multiplied by another. It is a bonus that is added up and capped, and then a set of modifiers that are multiplied together and capped separately. Getting those two layers the wrong way round is the commonest reason a suit does not hit as hard as its owner expected.

Open the calculator → and it does all of this for a real weapon and a real suit.

Layer one: the damage bonus, added and capped at 300%

Four skills and your items’ Damage Increase are added together, and the total is capped at 300%. The skill contributions are:

Tactics — skill ÷ 1.6, plus a further 6.25 at 100 or above
Anatomy — skill ÷ 2, plus a further 5 at 100 or above
Lumberjacking — skill ÷ 5, plus a further 10 at 100 or above, and only with an axe
Strength — STR × 0.3, plus a further 5 at 100 or above

At maximum those four come to 230.25%. Item Damage Increase adds up to another 100%, which is its own cap — and Divine Fury shares that same 100 [!], so a Chivalry character running it gets less from their items than the paperdoll suggests.

The two together can exceed 300, and the excess is thrown away. That is worth knowing before you chase the last few points of Damage Increase on a suit that is already there.

Honor on yourself sits outside that cap

Honoring yourself adds 25%, and it is added after the 300% cap is taken — so a suit already at 300% goes to 325%. [!] uo.com does not publish which layer Honor belongs to, or whether the cap binds it. Both halves are unpublished and are marked [!] in the tool wherever the figure appears.

Layer two: the modifiers, multiplied and capped at 3×

Slayers, Consecrate Weapon, Enemy of One, Perfection and the rest are a separate layer. They are multiplied together, the product is clamped to 3× [!], and only then applied. Two of them do nothing at all against another player: a slayer does not fire on a player, and Perfection is started by Honoring a creature, so it is a player-versus-monster engine.

The order, in one line

weapon damage × (1 + bonus ÷ 100), then × the clamped modifier product, then the target’s resists take their share of what lands.

What the tool does that a table cannot

It works the whole thing out for the weapon you are actually holding and the suit you have actually built — including swing speed, so you get damage per second rather than damage per hit, and including the target’s resists, which decide how much of a hit survives to the health bar. It defaults to a target at 70 across the board, because that is what a player suit is built to.

Open the damage and swing calculator →

Where these numbers come from

The skill contributions and the caps are from uo.com’s official wiki. How the modifier layer combines, and Divine Fury sharing the item cap, are unpublished: uo.com does not publish them. Anything uo.com does not publish carries a [!] as unpublished, both here and in the tool.

All of it describes official shards. Free shards run different numbers and a figure from one of them would be wrong here.