Test a belt router or balancer on real belts.

Hold a blueprint, press Ctrl+T, and Router Tester measures it using the game's own belt mechanics — not a simulation. It builds copies of your design on a separate test surface, runs every combination of supplied inputs and free outputs, and tells you exactly which cases fall short.

Your factory is never touched. The test surface is deleted when the run finishes.

Tests

• Quick — equal-size input/output combinations only. A fast first look.
• Throughput — every combination of supplied inputs and free outputs. Tells you whether your design is throughput unlimited.
• Balance — checks the outputs share the flow evenly, with a long measurement window for precision.

Results

• Throughput: UNLIMITED means every combination delivered full rate. Otherwise you get a list of the cases that fell short, with the rate on every input and output.
• Balance is judged with every output free — what a balancer actually guarantees. Universal balance (staying even when some outputs are blocked) is reported separately; most balancers don't have it, and that's not a fault.
• Every case is also written as a CSV file to your script-output folder.

How it works

No loaders, no chests. Each tick it pushes items onto every supplied input until the belt refuses them, and pulls items off every free output, counting. A blocked output simply isn't drained, so it backs up just like it would in your factory. Rates are measured against the belt's own speed, so any belt tier works.

Each copy of your design runs one load case and settles on its own schedule, and the settle time scales with the size of the build — large designs get the time they need to fill up before measuring.

Requirements

• Each input and output must be a plain belt (not a splitter or underground), with an empty tile behind each input and ahead of each output. If your design ends in a splitter, extend it by one belt tile.
• The full sweep has (2^inputs − 1) × (2^outputs − 1) cases, so around 8→8 is the practical limit.

Commands

/router-test            full throughput sweep
/router-test quick      equal-size combinations only
/router-test balance    balance test
/router-test status     progress
/router-test stop       stop and clean up

Multiplayer

Only one test runs at a time. The game speeds up while a test runs, which affects everyone, so all players are told when a test starts and finishes. Only the player who started a test, or an admin, can stop it.

Settings

Under Settings → Mod settings → Map: copies per batch, game speed while testing, measurement window, minimum settle time, and console output. The defaults suit most designs.