Machines needed per minute.

The one formula

The Factorio Lua API defines a recipe's time as the seconds it takes at crafting speed 1, and faster machines shorten it. Put together with the output count, one machine makes output x speed x 60 / seconds items a minute. Everything on this page is that line, rearranged.

For a target rate, divide the target by one machine's rate and round up. For a machine count, multiply the count by one machine's rate. The tool also reports seconds per item (craft time / (output x speed)), which is handy when a game shows time per item rather than per craft, and utilisation, which is the target divided by what the rounded-up machines can make.

Belts and lanes

If you enter a belt or lane capacity in items per minute, the tool divides the target by it and rounds up to tell you how many belts or lanes the output needs. Find the capacity in your game's own item or transport screen; it varies by tier and by game.

Worked example

Invented numbers, no game attached. A recipe makes 3 items every 8 seconds, and the machine runs at speed 1.25. One machine makes 3 x 1.25 x 60 / 8 = 28.125 items a minute, or one item every 2.133 seconds. For 45 a minute: 45 / 28.125 = 1.60, so build 2. Two machines make 56.25 a minute, so they run at 80% of capacity. If one lane carries 60 a minute, 1 lane is enough. Going the other way, 3 of these machines make 84.38 a minute.

What this page does not cover

It does not model power draw, ingredient supply, modules or beacons that change speed (enter the final speed multiplier yourself), productivity bonuses that add free output (fold the bonus into items per craft), or machines that idle waiting for ingredients.