BELT: Benchmark for Engine Limits & Throughput

BELT is a comprehensive benchmarking and testing suite for Factorio, providing multiple output formats, and powerful analysis tools for optimizing your designs.

Features

• Benchmarking - Benchmark a single save or a whole directory
• Blueprint testing - Automatically stamp and benchmark blueprints
• Cross-platform - Works on Windows, macOS, and Linux
• Multiple output formats - CSV and Markdown reports
• Pattern matching - Filter save files by name patterns
• Async execution - Fast parallel processing
• Verbose metrics support - Per-tick CSV exports for detailed Factorio metrics
• Sanitizer - Automatically parses and reports on belt-sanitizer mod output
• Chart-friendly exports - Clean benchmark artifacts that can be visualized by external tooling such as belt-charts

Quick Start

# Install BELT
cargo install belt

# Run benchmarks on all saves in a directory
belt benchmark ./saves --ticks 6000 --runs 5

# Filter saves by pattern and customize output directory
belt benchmark ./saves --pattern "inserter*" --output ./benchmark-results

Installation

Prerequisites

1. Factorio installed, BELT searches common installation paths, if none are found, please run with explicit --factorio-path.
2. Some save files to benchmark.
3. Rust if installing using cargo or building from source.

Windows

Follow this Visual C++ guide

From Crates.io

cargo install belt

From GitHub Releases

1. Download the latest binary for your platform from Releases
2. Extract and place in your PATH

From Source

git clone https://github.com/florishafkenscheid/belt.git
cd belt
cargo install --path .

Usage

Basic Commands

# Basic benchmark with default settings
belt benchmark /path/to/saves

# Customize benchmark parameters
belt benchmark /path/to/saves --ticks 12000 --runs 10

# Filter saves and specify output location
belt benchmark /path/to/saves --pattern "benchmark*" --output /path/to/output/dir

Command Reference

belt benchmark

Run benchmarks on one or more save files.

Arguments:

• <SAVES_DIR> - The location of the save(s) to be benchmarked.

Options:

Option	Description	Default
--ticks <TICKS>	How many ticks per run to run the benchmark for	6000
--runs <RUNS>	How many runs per save file	5
--pattern <PATTERN>	A pattern to match against when searching for save files in <SAVES_DIR>	*
--output <OUTPUT_DIR>	A directory to output the .csv and .md files to	.
--mods-dir <MODS_DIR>	A directory containing mods to be used for the benchmark	--sync-mods on each save file
--run-order <RUN_ORDER>	In which order to run the benchmarks. Available: sequential, random, grouped	grouped
--verbose-metrics <VERBOSE_METRICS>	Exports per-tick verbose metric CSVs for the selected metrics	none
--strip-prefix <PREFIX>	Strip a given prefix off of the save names	none
--headless <HEADLESS>	Whether or not to assume headless factorio	false
--record-cpu <RECORD_CPU>	Whether or not to log CPU frequency samples during benchmark runs	true

belt blueprint

Stamp blueprints into a base save.

Arguments:

• <BLUEPRINTS_DIR> - Directory containing blueprint files.
• <BASE_SAVE_PATH> - Base save file to stamp blueprints into.

Options:

Option	Description	Default
--count <COUNT>	Number of times to stamp each blueprint.	required
--buffer-ticks <BUFFER_TICKS>	Ticks to wait between stamping operations.	required
--mining-module-replacement <MINING_MODULE_REPLACEMENT>	Module to insert into mining drills after ore marker modules have been interpreted.	speed-module-3
--mining-module-replacement-quality <MINING_MODULE_REPLACEMENT_QUALITY>	Quality of replacement modules inserted into mining drills.	legendary
--bot-count <BOT_COUNT>	Number of construction bots to use for building.	0
--prefix <PREFIX>	Prefix to add to generated save names.	none
--pattern <PATTERN>	Pattern to match against when searching for blueprint files.	*
--output <OUTPUT_DIR>	Directory to output generated saves.	.
--mods-dir <MODS_DIR>	Directory containing mods to use.	--sync-mods on each save file
--headless <HEADLESS>	Whether or not to assume headless factorio	false

belt blueprint passes each blueprint string to the belt-sanitizer mod, which stamps it into the base save before generating the benchmark save. For mining setups, the sanitizer creates ore patches before reviving ghosts so drills can be built immediately. Ore selection is controlled by blueprint markers in this order:

Marker	Resource
stone-path tile	stone
concrete tile	iron-ore
hazard-concrete tile	coal
refined-concrete tile	copper-ore
refined-hazard-concrete tile	scrap
efficiency-module request	stone, iron-ore, copper-ore, coal, or uranium-ore for normal, uncommon, rare, epic, or legendary quality
efficiency-module-2 request	calcite, tungsten-ore, or scrap for normal, uncommon, or rare quality

Tile markers near a drill take precedence over module markers. After the resource is selected, mining-drill module requests are replaced with --mining-module-replacement and --mining-module-replacement-quality, so marker modules do not have to be the modules used in the final save.

belt sanitize

Run the belt-sanitizer mod on save files to track item/fluid production and consumption.

Arguments:

• <SAVES_DIR> - The location of the save(s) to be sanitized.

Options:

Option	Description	Default
--pattern <PATTERN>	A pattern to match against when searching for save files in <SAVES_DIR>	*
--ticks <TICKS>	How many ticks to run the sanitization for	3600
--mods-dir <MODS_DIR>	A directory containing mods to be used for the benchmark	--sync-mods on each save file
--data-dir <DATA_DIR>	If B.E.L.T. can't find your user data directory, pass it explicitely here.	none
--items <ITEMS>	A comma separated list of items to track.	none
--fluids <FLUIDS>	A comma separated list of fluids to track.	none
--headless	Whether or not to assume headless factorio	false

Global Options

Option	Description	Default
--factorio-path <PATH>	An explicit path to the factorio binary	Auto-detected
--verbose	Shows all debug statements	false

Examples

Example 1: Basic Benchmarking

# Run 3 benchmarks per save for 6000 ticks each
belt benchmark ./my-saves --ticks 6000 --runs 3

Example 2: Pattern Filtering

# Benchmark only saves starting with "science"
belt benchmark ./my-saves --pattern "science*" --output ./science-results

Example 3: Custom Factorio Path

# Specify explicit Factorio binary location
belt --factorio-path /path/to/factorio benchmark ./my-saves

Example 4: Blueprint Testing

# Stamp each blueprint 100 times with 60 tick buffer
belt blueprint ./blueprints ./base-save.zip --count 100 --buffer-ticks 60

Example 5: Item/Fluid Tracking

# Track specific items and fluids over 3600 ticks
belt sanitize ./saves --items "iron-plate,copper-plate" --fluids "water,crude-oil"

Charting Existing Data

BELT 4.0 no longer renders charts directly. Use the exported benchmark and verbose CSV files with external tooling such as belt-charts.

Advanced Usage

Best Practices

While belt benchmark offers sensible defaults, optimizing --ticks and --runs can refine your results. --ticks sets the simulation duration per run, while --runs determines the number of repetitions. Through testing, I've found that fewer runs with more ticks generally offers the most consistent UPS results for the shortest overall benchmark time, by reducing overhead from repeated Factorio launches. Experiment with these values for your specific saevs to find the optimal balance for accuracy and speed. However, for prolonged and thorough benchmarks, I recommend more runs in total, per save. This is because Factorio is deterministic, and when running BELT with verbose metrics, a "min" chart is generated. This chart is meant to combat any random noise that could slow down the Factorio benchmark, by only taking the fastest ticks of every run of a save.

Verbose Metrics

Here are all the verbose-metrics that are available: wholeUpdate,latencyUpdate,gameUpdate,planetsUpdate,controlBehaviorUpdate,transportLinesUpdate,electricHeatFluidCircuitUpdate,electricNetworkUpdate,heatNetworkUpdate,fluidFlowUpdate,entityUpdate,lightningUpdate,tileHeatingUpdate,particleUpdate,mapGenerator,mapGeneratorBasicTilesSupportCompute,mapGeneratorBasicTilesSupportApply,mapGeneratorCorrectedTilesPrepare,mapGeneratorCorrectedTilesCompute,mapGeneratorCorrectedTilesApply,mapGeneratorVariations,mapGeneratorEntitiesPrepare,mapGeneratorEntitiesCompute,mapGeneratorEntitiesApply,spacePlatforms,collectorNavMesh,collectorNavMeshPathfinding,collectorNavMeshRaycast,crcComputation,consistencyScraper,logisticManagerUpdate,constructionManagerUpdate,pathFinder,trains,trainPathFinder,commander,chartRefresh,luaGarbageIncremental,chartUpdate,scriptUpdate

Contributing

Any help is welcome. Whether you have never written a line of code, or simply don't know Rust. This is what the CI/CD pipeline is for! Bug reports and feature requests can be submitting through GitHub Issues.

If you want to contribute, please open an issue to discuss the proposed changes before submitting a pull request.

Standards

On every push a linter and formatter checks the code, so just write the code however you want and fix any errors that occur.

Note

To do this locally, run cargo fmt and cargo clippy -- -D warnings

I follow the Conventional Commits specification as a standard for my commit messages, I can only encourage you do the same.

Credits

This was heavily inspired by abucnasty's videos. I wanted to make a more universal, cross-platform version of the existing ps1 script. belt sanitize's settings.rs file was inspired by the Typescript work of justarandomgeek