# printfn/fend

Arbitrary-precision unit-aware calculator

Repository: https://github.com/printfn/fend
Canonical: https://ross.abutalabs.com/products/fend
Homepage: https://printfn.github.io/fend
Language: Rust
License: MIT
License Family: permissive
Topics: calculator, rust, units-of-measure
Last push: 2026-07-21T11:38:09+00:00

## Health v2 (maintenance only)
Score: 77/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 93, release rhythm 43, longevity 100
- inputs: {"age_days": 2224, "days_push": 43, "days_rel": 221, "gap_med": 117, "n_releases_24m": 6}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1027, forks 72 (observed 2026-08-28T04:03:16.985834+00:00)

## What it is
fend is an arbitrary-precision, unit-aware calculator written in Rust, available as a CLI REPL, a Rust library (fend-core), and a web interface. It supports SI, US/UK customary and historical units, complex numbers, variables, multiple number bases, dice rolls, and lambda calculus.

## Use cases
- convert 1 ft to cm from the terminal
- do arbitrary-precision math without floating point errors
- calculate with units of measure like SI and imperial units
- convert between hex, binary, octal and other bases
- roll D&D-style dice from the command line
- embed a unit-aware calculator into a Rust application

## When to choose
- you need a fast terminal calculator with unit conversion
- you need exact rational arithmetic instead of floating point
- you want a calculator library to embed in Rust projects

## When to avoid
- you need a full spreadsheet or symbolic algebra system (CAS)
- you need graphing or plotting capabilities

## Facets
- artifact type: cli-tool
- maturity: active
- function: math, cli
- domain: mathematics, developer-tools
- platform: cli, cross-platform, windows
- tags: calculator, units-of-measure, arbitrary-precision, unit-conversion, repl, rust, command-line, linux, macos, web-server

## Member repositories
- printfn/fend (main) score 77

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:03:16.985834+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T07:07:54.300833+00:00, confidence not recorded.
  - readme: https://github.com/printfn/fend (fetched 2026-08-28T04:03:16.985834+00:00, sha aa4b837a28b2)
  - homepage: https://printfn.github.io/fend (fetched 2026-08-29T13:08:02.662314+00:00, sha 221f5cd04146)
  - registry_crates: https://crates.io/api/v1/crates/fend (fetched 2026-08-29T13:08:02.664726+00:00, sha 30d1bade5454)
- Data as of 2026-08-30T08:39:29.467469+00:00.