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Factor is a Web app that aims to be an alternative to spreadsheets for calculating production rates and ratios in factory games (like Factorio or Satisfactory).

Try it online at: (Or you can run it yourself! See the Development section.)

Factor is...

  • Entirely client-side (everything is stored in your browser's local storage.)
  • Game-agnostic (The available items/recipes/etc. are fully editable.)
  • Written with Clojurescript and re-frame (among other dependencies!)

Basic usage:

  1. Input all the Items, Machines, and Crafting Recipes available in the game you're playing.
    • Note that in Factor, different types of items -- fluid, gas, etc. -- are all treated the same way.
  2. Create a Factory and set the Desired Output of the factory to the items you want to produce (e.g. "1 blue science per second").
  3. Factor will calculate a Production Graph for the factory that indicates exactly what machines and recipes you need to meet your desired output.


The following is a list of high-level features/capabilities that I want to build into Factor.

  • Checked-off features like this are supported.
  • Unchecked features are unsupported, but may be supported in the future.

Here's the list:

  • Create/edit Items (e.g. Iron ore).
  • Create/edit Machines (e.g. Smelter).
    • Machines can have a power.
    • Machines can have a speed.
  • Create/edit Recipes (e.g. Smelt iron ore).
    • Recipes can have any number of inputs and outputs.
    • Recipes can specify a list of compatible machines.
    • Recipes have a configurable :duration
    • The list of compatible machines can be prioritized.
    • Recipes can specify a power modifier.
    • Recipes can include catalysts (items only required at startup, not per craft).
  • Create/edit Factories (e.g. Starter base)
    • Factories have configurable desired outputs (e.g. 1 blue research per second).
    • Factories can generate a Production Graph that shows what recipes can be used to produce the desired output.
      • The production graph is rendered as a Production Tree for users to visualize.
      • The graph is exportable to dot code
      • The graph is renderable in the browser
      • Circular dependencies are supported. (when Recipe A's output is required for Recipe B, and Recipe B's output is required for a predecessor of Recipe A)
        • The "seed items" required for the circular dependency are calculated and included in the factory's catalysts.
      • Production graph calculation takes machine speed into account.
    • Factories can specify machines/recipes/items to exclude (e.g. don't use Recipe A for given factory.) Should support both allow-lists and deny-lists, in hard and soft variants. ("Soft" meaning it's a preference -- things in a soft-deny list will only be picked if there are no soft-denied alternatives. Things in a hard-deny list will never be picked.)
    • Factories can report the overall power usage required for all machines.
    • Factories include a "checklist" of all the machines needed to build the factory.
  • All quantities/rates have units (e.g. J, W, items/sec, etc.)
    • Units are configurable in settings.
    • Units are presented in human-readable form (e.g. 2.3 MW instead of 2300 W)
    • Units support conversions between them (e.g. changing unit from items/sec to items/min converts values by multiplying by 60)
  • URL-based routing (including pushing history and supporting deep links to sub-pages.)
    • Ability to generate "share URLs" that contain your whole world in the URL.
  • Import/Export
    • World data can be exported as EDN
    • EDN world data can be imported.
    • You can load presets from popular games
      • Factorio
  • Bulk-Editing
    • Ability to bulk-edit recipes (e.g. remove a certain machine from a bunch of recipes at once)
  • Conveyor/Inserter Calculator


  • Catalyst: A catalyst is a one-time requirement for crafting recipes. Catalysts can either be items that aren't consumed in crafting (e.g. a "Gear casting mold" used to make gears) or that are consumed to kickstart a self-sustaining reaction (e.g. a hohlraum).
  • Factory: Represents a player-built, self-contained production system that produces some desired outputs. For example, perhaps your factory's desired output is "One supercomputer per second." The factory contains all the various machines required to produce the output, which could include multiple stages of complex crafting.
  • Item: Represents an in-game item that is produced/consumed/conveyed/stored. e.g. "Iron ore" would be an item, and so would "Water" and "Research cube."
  • Preset: A preset is a built-in world that ships with Factor and can be imported from the Settings page. (Note: I haven't built out any presets yet, but the framework is in place.)
  • Production Graph (pgraph): A directed, cyclic graph that represents the flow of items within a factory. The nodes of the graph represent a bank of machines in the factory, all processing the same recipe (e.g. three Smelters using the "Smelting iron ore" recipe would be grouped in a single node.) The edges of the graph represent the flow of items between the banks of machines. Factor can automatically calculate a Production Graph for your factories.
  • Production Tree: A simplified view of a Production Graph, used for display purposes. Some types of pgraphs can be directly represented as a tree, but many pgraphs don't have a tree-like structure, in which case the calculated production tree will have to list some nodes more than once (as children of different parents).
  • Recipe: Represents an in-game crafting recipe. The recipe describes a crafting operation that consumes certain inputs to produce some outputs. (e.g. consuming iron ore to produce iron plates.) Recipes can also specify catalysts required to bootstrap crafting, what machines can be used to craft, and a duration of the crafting operation. (Note that even resource collection is modeled as a recipe: the ability to mine coal would be represented as a recipe that outputs coal and has no inputs.)
  • World: The "world" is a piece of data that encapsulates everything that models in-game entities -- namely, all items, machines, recipes, and factories. It doesn't contain personal configuration (e.g. units) or UI state (e.g. which factory is open by default). Factor can import/export worlds; it's recommended to export your world occasionally for backup purposes. You can also share it with your friends!

Developer-facing terms

Used in Factor's codebase and developer documentation.

  • Database: Factor's "database" is just an in-memory map accessed using the conventions of re-frame. There is NO server-side database in Factor (or indeed, any network access at all!)
  • Migration: In the context of Factor, a "migration" is a function that performs some modifications on application data when it's loaded from local storage or imported by the user. Whenever a breaking change is made in the schema, a corresponding migration function is defined to update old versions of the database. All migrations are idempotent and are always applied; there is no state tracking of which migrations have/haven't been run.
  • Quantity map (qmap): Widely used in the codebase, a qmap is a hash-map where keys are opaque strings (usually the IDs of items/machines) and values are a numeric quantity. Quantities can be floating-point, but zero or negative values are not allowed in a qmap.

Production Graphs

Under the hood -- but not very far under! -- Factor models the flow of items through a factory using a directed graph. The nodes of the graph represent groups of machines that are processing a recipe (e.g. "12 smelters using the Smelt iron ore recipe" would be one node) and the edges represent the flow of items between them.

Each edge has an associated quantity-map that defines the amount of items flowing along it.

Edges must follow an important constraint: The sum of the quantities of the edges pointing to a node must equal the node's specified inputs. Inversely, the sum of the quantities of the edges pointing from a node must equal the node's specified outputs.

There are two "special" nodes for which the above constraint does not apply: the missing node and excess node, which are used to "balance" the I/O of the pgraph. For example, if a recipe produces two outputs but only one is consumed by the next recipe, the "excess" output is connected to the excess node. Similarly, if a recipe is not satisfied (i.e. requires inputs not produced within the pgraph itself), those missing inputs are connected to the missing node. In this way, missing inputs and excess outputs are modeled without violating the edges-sum constraint.

For technical users, it can be helpful to understand how Factor constructs (aka "satisfies") a production graph (pgraph) for your factory.

A summary of the process:

  1. An "empty" pgraph is created. It's called "empty" because it models an empty processing chain -- like a factory with no machines. No edges exist in the graph yet. It has two nodes, though: the special missing and excess nodes are created in this step.
  2. A node is added to the pgraph to represent the desired output for the factory. This is called the desired node, and it consumes the desired items as input.
    • Since there are no other nodes to produce the desired items, an edge is created from missing -> desired to indicate that all the desired items are missing.
  3. Factor looks for a recipe that produces some or all of the items that are currently being provided by the missing node.
    • If no such recipes can be found or the missing node isn't providing any items, the pgraph is said to be satisfied and steps 4-5 is skipped.
  4. If such a recipe is found, Factor decides what machines, and how many, should process the recipe. This combo of recipe+machine+number is called a "candidate."
    • If more than one candidate is found, Factor picks one of them -- a process called "candidate selection."
    • If no candidates can be selected (e.g. because of a hard deny-list), pgraph is said to be satisfied and step 5 is skipped.
  5. Once a candidate is selected, Factor adds a node for that candidate to the pgraph, and then iteratively connects the inputs and outputs of that nodes to other nodes where they may be produced/consumed.
    • If the node has any inputs that aren't produced anywhere, they are provided from the missing node. If the node produces outputs that aren't needed anywhere, they are sent to the excess node.
    • Factor may produce cyclical connections -- single nodes feeding into themselves, and more complex cycles involving multiple nodes. Whenever your factory includes a cyclical connection, you'll need to bootstrap some part of processing when the factory is built in-game. (e.g. if items flow from X -> Y -> Z -> X, you will need to get some of the output of X, Y, or Z to bootstrap the cyclical crafting process.)
  6. Repeat steps 3-5 until the pgraph is determined to be satisfied. The algorithm is done! 🎉


This section of the README describes how to compile and run Factor on your own computer. Note that this isn't necessary for normal usage (you can visit instead), but is necessary if you want to hack on Factor yourself.

Factor source code is available in two locations:

The project is written with Clojurescript and compiled with shadow-cljs. In order to compile the site, you will need:

  • Java SDK 8
  • Node 6+ (w/NPM)

Before you build the site, install Node dependencies (this will pull in the shadow-cljs toolchain as well as runtime JS dependencies):

git clone
cd factor
npm install

All common operations in the project are exposed as NPM scripts. To generate a minified, production-ready bundle, run:

npm run build

The resulting site will be in the public/ directory, and can be served by any HTTP server, for example:

cd public
python -m http.server

For building/running Factor during development, run:

npm run start

This will:

  • Compile Factor and automatically recompile when source files are modified.
  • Run tests and automatically re-run when source files are modified.
  • Serve Factor at localhost:8080
  • Provide an nREPL server

(Tip: The VSCode extension Calva provides quick-and-easy nREPL integration: Install the extension, run npm run start, and do Ctrl-Alt-c Ctrl-Alt-c, then hit Enter three times, and you've got a REPL!)

My "official" version of Factor ( is published from, via and Netlify.

To run tests like the CI/CD pipeline will, use:

npm run test


A companion Web app for games like Factorio