Units
The following units are important in Factorio.
Not all game elements are simulated physical correctly (for example the weight of items, currently no entity has a weight, the weight is measured in how many items can fetch into one stack), but those on this pages are!
Power
Power is defined as work being done per unit of time.
Watt (W)
The basic unit of power is 1 watt (W), which is defined as 1W = 1J / 1s, ie. one Joule of work being done every second.
The game commonly deals with larger units, namely kilowatts (kW) and megawatts (MW).
Lamps use 5kW while turned on. A Radar uses 300kW while active - equivalent to 60 lamps. One Steam engine is capable of outputting 510kW.
Work
Work is defined as a transfer of energy, or as energy being "spent".
Joule (J)
The basic unit of work is 1 joule (J), and represents the work being done (total energy transferred) by a power of one watt applied for one second: 1J = 1W * 1s.
In-game, Fuel is nothing than work. For example, every piece of coal burned will produce 8kJ. One Basic accumulator is capable of storing 5MJ.
It doesn't make much sense to calculate work with the (in real-world) much more common kilo Watt hours (kWh, 1 kWh = 3600 kJ), cause the game runs more or less in real-time and it is not useful to calculate that case with hours.
Time
Tick (1/60s)
A 1/60 second in game. This is the shortest time fraction, the game handles.
Second (s)
One second in-game. This is not guaranteed to correspond to one real second. For example, slow computers may not manage to calculate an entire tick during the corresponding real time frame of 1/60th of a second.
Day
A day has 25000 Game-ticks or 416.66 game-seconds (= 6.94 Game-minutes).
Distance / Space
Tile
The Tile is both used as a unit of distance/length and a unit of area. For example, the size of an object may be expressed as "2x2 tiles", which means the object covers an area of 4 square tiles or tiles². The unit of square tiles is often simplified into Tiles. It can be assumed, that a tile has the length of 1 meter.
Chunk
A Chunk is a quadratic area where one side is 32 tiles long. (1024 square tiles)
Logistics
Throughput
Basically items per time, or fluid-units per time.
On Belts
Throughput = speed * density
See Transport belts.
For Logistic robots
Throughput depends on the distance, the number of robots and their item-stacksize. Let's assume a robot can travel 1 tile per second and can transport only one item at once. It needs also to return. Then this robot can transport 1/2 item per second. If you use 2 you can transport 1 item per second. If you double the distance, we are again at 1/2 item per second.
For train
(Unfinished. Needs to consider also the loading and unloading time, needs to consider maximum speed...)
Capacity
Basically items per transport-unit. This depends in many cases on the item-type you use. A Cargo wagon has a capacity for 1000 items for ore, or 2000 for steel- or copper-plates.
Capacity in Stacks
A Cargo wagon has for example 20 stacks. The capacity of the wagon is 20 stacks. But the capacity of a stack depends on, what type of item you put into, so when stacks come into play, you need to say "Capacity of 20 stack iron-ore".
See also
(Missing here: Capacity, which is either the volume of something or Productive capacity; Load, which is a measurement about the tightest bottleneck (waiting or running items))