GitPedia

Insect

High precision scientific calculator with support for physical units

From sharkdp·Updated June 14, 2026·View on GitHub·
·Archived

you can read more about why Insect has been rewritten from scratch [here](https://github.com/sharkdp/numbat/blob/master/assets/reasons-for-rewriting-in-rust.md). The project is written primarily in PureScript, distributed under the MIT License license, first published in 2017. It has gained significant community traction with 3,169 stars and 127 forks on GitHub. Key topics include: calculator, mathematical-expressions, parser, physics, purescript.

Latest release: v5.9.0
July 23, 2023View Changelog →

Note: Please consider using the follow-up project instead: Numbat.

you can read more about why Insect has been rewritten from scratch here.

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insect

A high-precision scientific calculator with full support for physical units.

Contents

Documentation

  • Evaluate mathematical expressions:

    1920/16*9
2^32
sqrt(1.4^2 + 1.5^2) * cos(pi/3)^2

    • Operators: addition (+), subtraction (-), multiplication
      (*, ·, ×), division (/, ÷, per), exponentiation (^,
      **). Full list: see Reference below.

    • Mathematical functions: abs, acos, acosh,
      acot/arccotangent, acoth/archypcotangent,
      acsc/arccosecant, acsch/archypcosecant, arcsecant,
      asech/archypsecant, asin, asinh, atan2, atan, atanh,
      ceil, cos, cosh, cot/cotangent, coth/hypcotangent,
      csc/cosecant, csch/hypcosecant, exp, floor,
      fromCelsius, fromFahrenheit, gamma, ln, log10, log,
      maximum, mean, minimum, round, secant, sech/hypsecant,
      sin, sinh, sqrt, tan, tanh, toCelsius, toFahrenheit.

    • High-precision numeric type with 30 significant digits that
      can handle very large (or small) exponents like 10^(10^10).

    • Exponential notation: 6.022e23.

    • Hexadecimal, octal and binary number input:

      0xFFFF
0b1011
0o32
0x2.F
0o5p3

  • Physical units: parsing and handling, including metric prefixes:

    2 min + 30 s
40 kg * 9.8 m/s^2 * 150 cm
sin(30°)

    • Supported units: see Reference section below.

    • Implicit conversions: 15 km/h * 30 min evaluates to 7.5 km.

    • Useful error messages:

      > 2 watts + 4 newton meter

Conversion error:
  Cannot convert unit N·m (base units: kg·m²·s⁻²)
              to unit W (base units: kg·m²·s⁻³)

  • Explicit unit conversions: the -> conversion operator (aliases:
    →, ➞, to):

    60 mph -> m/s
500 km/day -> km/h
1 mrad -> degree
52 weeks -> days
5 in + 2 ft -> cm
atan(30 cm / 2 m) -> degree
6 Mbit/s * 1.5 h -> GB

  • Variable assignments:

    Example: mass of the earth

    r = 6000km
vol = 4/3 * pi * r^3
density = 5 g/cm^3
vol * density -> kg

    Example: oscillation period of a pendulum

    len = 20 cm
2pi*sqrt(len/g0) -> ms

    • Predefined constants (type list to see them all): speed of
      light (c), Planck's constant (h_bar), electron mass
      (electronMass), elementary charge (elementaryCharge), magnetic
      constant (µ0), electric constant (eps0), Bohr magneton (µ_B),
      Avogadro's constant (N_A), Boltzmann constant (k_B),
      gravitational acceleration (g0), ideal gas constant (R), ...

    • Last result: you can use ans (answer) or _ to refer to the
      result of the last calculation.

  • User-defined functions:

    Example: kinetic energy

    kineticEnergy(mass, speed) = 0.5 * mass * speed^2 -> kJ

kineticEnergy(800 kg, 120 km/h)

    Example: barometric formula

    P0 = 1 atm
T0 = fromCelsius(15)
tempGradient = 0.65 K / 100 m

pressure(height) = P0 * (1 - tempGradient * height / T0)^5.255 -> hPa

pressure(1500 m)

  • Sums and products:

    Syntax:

    sum(<expression>, <index-variable>, <from>, <to>)
product(<expression>, <index-variable>, <from>, <to>)

    Examples:

    # sum of the first ten squares
sum(k^2, k, 1, 10)

# the factorial of n as the product 1 × 2 × ... × n
myFactorial(n) = product(k, k, 1, n)

  • Unicode support:

    λ = 2 × 300 µm
ν = c/λ → GHz

  • And more: tab completion, command history (arrow keys,
    Ctrl+R), pretty printing, syntax highlighting, ...

Reference

Pros and cons

Reasons to use Insect

  • Insect is open-source.
  • There is a web version that requires no
    installation    .
  • With both browser and terminal versions available, Insect is truly
    cross-platform.
  • Insect has first-class support for physical units, including
    metric and binary prefixes. While evaluating your calculation, Insect
    ensures that you did not accidentally make any mistakes in combining
    the physical quantities.
  • Insect supports an
    interactive style with its
    readline-like interface. There is a saved history that can be browsed
    by pressing the up and down arrow keys. The history is also searchable
    via Ctrl-R.
  • Insect's syntax is rather strict. The parser does not try to be
    "smart" on syntactically incorrect input, so there shouldn't be any
    surprises - and you can trust the result of your calculation. The
    parsed user input is always pretty-printed for a quick double-check.
  • Insect is written in PureScript and
    therefore benefits from all the safety guarantees that a strictly
    typed functional programming language gives you.
  • The source code of
    purescript-quantities
    (the underlying library for physical units) as well as the code of
    Insect itself is extensively tested.

Reasons to choose an alternative

  • Insect is a scientific calculator. It's not a computer algebra system
    that solves differential equations or computes integrals. Try
    WolframAlpha instead.
  • There is no graphical user interface with buttons for each action
    (x², 1/x, DEG/RAD, etc.).
    Qalculate! is a fantastic tool that
    supports both text as well as graphical input.
  • Insect supports a huge range of physical units: all SI
    units    ,
    all non-SI units that are accepted by SI as well as most units of the
    imperial and US customary systems (and many more). However, if you
    need something even more comprehensive, try GNU
    units    .
  • Insect is not a general-purpose programming language. You could try
    Frink.
  • Insect does not have a special mode for hexadecimal, octal, or binary
    numbers (yet), though it does support inputting them.

FAQ

  • Why are Celsius and Fahrenheit not supported?

    In contrast to the SI unit of temperature, the
    Kelvin, and to all other
    units, Celsius and Fahrenheit both require an additive offset when
    converting into and from other temperature units. This additive offset
    leads to all kinds of ambiguities when performing calculations in
    these units. Adding two temperatures in Celsius, for example, is only
    meaningful if one of them is seen as an offset value (rather than as
    an absolute temperature). Insect is primarily a scientific calculator
    (as opposed to a unit conversion tool) and therefore focuses on
    getting physical calculations right.

    Even though °C and °F are not supported as built-in units, there
    are helper functions to convert to and from Celsius (and Fahrenheit):

    • fromCelsius takes a scalar value that represents a temperature
      in Celsius and returns a corresponding temperature in Kelvin:

      > fromCelsius(0)

   = 273.15 K

> k_B * fromCelsius(23) to meV

   = 25.5202 meV

    • toCelsius takes a temperature in Kelvin and returns a scalar
      value       that represents the corresponding temperature in Celsius:

      > toCelsius(70 K)

   = -203.15

> toCelsius(25 meV / k_B)

   = 16.963

  • Why is 1/2 x parsed as 1/(2x)?

    Implicit multiplication (without an explicit multiplication sign)
    has a higher precedence than division (see operator precedence
    rules    ). This is by design, in order to parse inputs like
    50 cm / 2 m as (50 cm) / (2 m). If you meant ½ · x, write
    1/2 * x.

  • What is the internal numerical precision?

    By default, Insect shows 6 significant digits in the result of the
    calculation. However, the internal numerical precision is much higher
    (30 digits).

  • How does the conversion operator work?

    The conversion operator -> attempts to convert the physical quantity
    on its left hand side to the unit of the expression on its right
    hand side. This means that you can write an arbitrary expression on
    the right hand side (but only the unit part will be extracted). For
    example:

    # simple unit conversion:
> 120 km/h -> mph

  = 74.5645 mi/h

# expression on the right hand side:
> 120 m^3 -> km * m^2

  = 0.12 m²·km

# convert x1 to the same unit as x2:
> x1 = 50 km / h
> x2 = 3 m/s -> x1

  x2 = 10.8 km/h

  • What is the relation between the units RPM, rad/s, deg/s and
    Hz?

    The unit RPM
    (revolutions per minute) is defined via 1 RPM = 1 / minute where the
    1 on the right hand side symbolizes "1 revolution".

    As the base unit is the same (1 / second), RPM can be converted to
    rad / s, deg / s or Hz. Note, however, that 1 RPM does not
    equal 2π rad / min or 360° / min or 1 Hz, as some might expect.
    If you're interested in computing the traversed angle of something
    that rotates with a given number of revolutions per minute, you need
    to multiply by 2π rad or 360° because:

    1 RPM · (360°/revolution) = (1 revolution / minute) · (360° / revolution) = 360° / minute

Terminal version

In addition to the web interface, there is also a command-line version
(supporting Node.js 10 and later) which can by installed via
npm:

npm install -g insect

Note that you should almost always never run this as root or with
sudo. If the command fails due to permission issues, set up a prefix
directory
and call npm install as a user instead.

For Arch Linux, there is an AUR
package:

yaourt -S insect

For macOS, there is a Homebrew
formula:

brew install insect

For Android, install Termux from
F-Droid. Install Node.js in
Termux and then install insect from npm:

pkg install nodejs-lts
npm install -g insect

Development

Insect is written in PureScript (see the Getting
Started
guide). First, install all dependencies:

npm install

To start the web version:

npm start

To build a bundled JavaScript file that you can run from the terminal
(note that this builds the web version too):

npm run build

To run the index.cjs file which the previous command creates:

node index.cjs
# Or simply on Un*x
./index.cjs

Note that it's not possible to just move this file anywhere and then run
it there, since it depends on packages in node_modules.

Insect comes with a comprehensive set of unit tests.
To run them:

npm test

Note that Node.js 12 or above is required to work on/build Insect
(despite Insect itself requiring only Node.js 10 or later to run). If
you don't have or want to install Node.js 12 or later, you can use the
following Dockerfile to build or run Insect on Node.js 18:

Dockerfile
FROM node:18

WORKDIR /usr/src/insect

COPY . .

RUN npm install && \
    npm run build

CMD ["node", "index.cjs"]

After creating the image (docker build -t sharkdp/insect .), you can
create the container and copy out the build artifacts:

docker create sharkdp/insect:latest
# copy SHA (e.g. 71f0797703e8)
docker cp 71f0797703e8:/usr/src/insect/index.cjs .
docker cp -r 71f0797703e8:/usr/src/insect/node_modules .

To directly run Insect inside Docker (paying a heavy startup time
penalty), you can use:

docker run -it --rm -v ~/.local/share/insect-history:/root/.local/share/insect-history sharkdp/insect:latest

Maintainers

Contributors

Showing top 12 contributors by commit count.

sharkdp

sharkdp

318 commits

triallax

triallax

63 commits

dependabot[bot]

dependabot[bot]

23 commits

n4bb12

n4bb12

16 commits

septatrix

septatrix

6 commits

benmaddison

benmaddison

5 commits

colinwahl

colinwahl

2 commits

jimmo

jimmo

2 commits

nunomarks

nunomarks

2 commits

justinwoo

justinwoo

2 commits

anilanar

anilanar

1 commits

archisman-panigrahi

archisman-panigrahi

1 commits

View all contributors on GitHub →

This article is auto-generated from sharkdp/insect via the GitHub API.Last fetched: 6/17/2026