To use this tool, input the troop levels, counts, and HP for each army and fill in other relevant data. Leaving something out or misspecifying something can often result in large differences from the game result. To run the battle click one of the "Start Battle" buttons.
To get a general explanation of how the battle mechanics work check out the Call of War wiki regarding combat.
Ranged units have the same range at all levels. Artillery types and cruisers have a range of 50, battleships have 75, and railroad guns have 100. The only exception is Axis railroad guns which have 110. For the purposes of the calc all planes are melee units so their range is effectively 5 km.
To account for protection from bunkers and the damage done to bunkers as the battle progresses, you must add a bunker building along with its level and HP. You should also add any other buildings that are in the province so the damage can be calculated accurately. If the province has buildings but no bunker it will make no difference to the battle. However, you can add buildings without a bunker if you want to estimate building damage.
Only a single stack at a given position should be assigned the buildings. All other land stacks at the same position as the stack assigned buildings (except aircraft transport) will inherit the same set of buildings. If the buildings include a bunker, all of these stacks will receive the fortification bonus. When any of these stacks are involved in an attack or defense the appropriate building damage will be applied. In general, it should work as in-game.
If there is a stack at or near the same position that shouldn't receive the fortification bonus, such as an allies stack or a stack just outside the province nexus you can give it, assuming the buildings are at position 0 km, position 1, 2, or 3 km. That way they will still be within melee range for the battle, but won't recieve the fort protection.
If there is a bunker with other buildings it is a good idea to run the calculation multiple times with "Simulate Variance" checked. The battle results can vary dramatically when there is a bunker with other buildings. More and higher level buildings can lead to more extremes. The variance will also depend on how much damage the enemy can do to buildings. Without "Simulate Variance" the result will show the average expected result of the battle.
1. The number of remaining hit points for this unit (e.g. 17.3), or
2. The percentage of the maximum HP followed by % (e.g. 85%).
If a unit is at max HP but you don't know exactly how many hit points it has you can just use 100%.
If you have a stack with a single unit type/level and you click on the stack in-game it will show you how many remaining hit points it has.
For a stack with multiple unit types you can click on the army details panel to see the remaining HP of each unit type, e.g.
For plane strikes the calc will assume you are sending the same stack of planes to the target repeatedly until one side dies (just like any other battle), unless you set the "Max Rounds" parameter. To simulate a single bombing run set "Max Rounds" to 1. For rockets a single strike is calculated regardless of what Max Rounds is set to. You may want to set the max rounds to 1 or some other number for any type of battle to see what will happen in a fixed number of rounds.
If this is checked the unit counts and HP values will be replaced with those that are left after the battle. This is particularly use in combination with Max Rounds as you can do one round at a time and see how the condition of the armies change round by round.
If you check this the results of an attack will be opened in a new browser tab. This may be useful if you want to search for various optimal combinations but don't want to lose the results of previous tests.
If you check this the calculator with simulate randomness in the battle as is done in the game. Rerunning the battle a bunch of times with this enabled can give you an idea of the distribution of possible outcomes. Here is a forum post with more information about it: "Simulate Variance" in dxcalc
If buildings are specified this option will cause damage to buildings in a random way as is done in-game. See Fortresses and buildings for more info.
The number of dead units of each type is indicated as well as the hit-points lost. Damage to buildings is also shown. A summary table of the overall battle is shown for each side that includes lost HP and time and resources required to rebuild the lost units. If the optional "Update Counts" is specified at the bottom, the unit count and HP input fields are replaced with resulting values.