How do I figure out production ratios in Factorio?

In Factorio, production ratios boil down to how many items a single machine can craft per second and how that scales to your overall goal. A recipe has a base crafting time called energy_required (in seconds) and a produced per-craft amount; a crafting machine has a crafting_speed. The general formula for a single machine is: per_second_rate = produced_per_craft × (crafting_speed / energy_required). For example, with a typical assembler (crafting_speed 0.5) on a 0.5-second recipe that yields 1 item per craft, you get 1 item per second. Upgrading to a faster assembler (crafting_speed 1.25) yields 2.5 items per second. If you’re using productivity modules or beacons, multiply by their speed/productivity impact to get the final rate. For the underlying definitions, see the official docs on energy_required and crafting_speed. official guide and CraftingMachinePrototype. Beacons further boost final crafting speed, though be mindful of diminishing returns. Beacon and Productivity module pages explain these effects. Finally, verify input capacity against belt throughput (basic belts ~7.5 items/s per lane; 15 items/s total on a standard belt) to ensure your inputs aren’t bottlenecked. Transport belts/Physics. Rate Calculator mod can automate these calculations for you.