A handy utility for converting between quantities in different units.

npm install convert-units --save

convert-units has a simple chained API that is easy to read.

Here's how you move between the metric units for volume:

var convert = require('convert-units')

convert(1).from('l').to('ml')
// 1000

Jump from imperial to metric units the same way:

convert(1).from('lb').to('kg')
// 0.4536... (tested to 4 significant figures)

Just be careful not to ask for an impossible conversion:

convert(1).from('oz').to('fl-oz')
// throws -- you can't go from mass to volume!

You can ask convert-units to select the best unit for you. You can also optionally explicitly exclude orders of magnitude or specify a cut off number for selecting the best representation.

convert(12000).from('mm').toBest()
// 12 Meters (the smallest unit with a value above 1)

convert(12000).from('mm').toBest({ exclude: ['m'] })
// 1200 Centimeters (the smallest unit excluding meters)

convert(900).from('mm').toBest({ cutOffNumber: 10 });
// 900 Centimeters (the smallest unit with a value equal to or above 10)

convert(1000).from('mm').toBest({ cutOffNumber: 10 })
// 10 Meters (the smallest unit with a value equal to or above 10)

You can get a list of the measurement types supported with .measures

convert().measures()
// [ 'length', 'mass', 'volume' ]

If you ever want to know the possible conversions for a unit, just use .possibilities

convert().from('l').possibilities()
// [ 'ml', 'l', 'tsp', 'Tbs', 'fl-oz', 'cup', 'pnt', 'qt', 'gal' ]

convert().from('kg').possibilities()
// [ 'mcg', 'mg', 'g', 'kg', 'oz', 'lb' ]

You can also get the possible conversions for a measure:

convert().possibilities('mass')
// [ 'mcg', 'mg', 'g', 'kg', 'oz', 'lb', 'mt', 't' ]

You can also get the all the available units:

convert().possibilities()
// [ 'mm', 'cm', 'm', 'in', 'ft-us', 'ft', 'mi', 'mcg', 'mg', 'g', 'kg', 'oz', 'lb', 'mt', 't', 'ml', 'l', 'tsp', 'Tbs', 'fl-oz', 'cup', 'pnt', 'qt', 'gal', 'ea', 'dz' ];

To get a detailed description of a unit, use describe

convert().describe('kg')
/*
  {
    abbr: 'kg'
  , measure: 'mass'
  , system: 'metric'
  , singular: 'Kilogram'
  , plural: 'Kilograms'
  }
*/

To get detailed descriptions of all units, use list.

convert().list()
/*
  [{
    abbr: 'kg'
  , measure: 'mass'
  , system: 'metric'
  , singular: 'Kilogram'
  , plural: 'Kilograms'
  }, ...]
*/

You can also get detailed descriptions of all units for a measure:

convert().list('mass')
/*
  [{
    abbr: 'kg'
  , measure: 'mass'
  , system: 'metric'
  , singular: 'Kilogram'
  , plural: 'Kilograms'
  }, ...]
*/

• mm
• cm
• m
• in
• ft-us
• ft
• fathom
• mi
• nMi

• mm2
• cm2
• m2
• ha
• km2
• in2
• ft2
• ac
• mi2

• mcg
• mg
• g
• kg
• oz
• lb
• mt
• t

• mm3
• cm3
• ml
• l
• kl
• m3
• km3
• tsp
• Tbs
• in3
• fl-oz
• cup
• pnt
• qt
• gal
• ft3
• yd3

• mm3/s
• cm3/s
• ml/s
• cl/s
• dl/s
• l/s
• l/min
• l/h
• kl/s
• kl/min
• kl/h
• m3/s
• m3/min
• m3/h
• km3/s
• tsp/s
• Tbs/s
• in3/s
• in3/min
• in3/h
• fl-oz/s
• fl-oz/min
• fl-oz/h
• cup/s
• pnt/s
• pnt/min
• pnt/h
• qt/s
• gal/s
• gal/min
• gal/h
• ft3/s
• ft3/min
• ft3/h
• yd3/s
• yd3/min
• yd3/h'

• C
• F
• K
• R

• ns
• mu
• ms
• s
• min
• h
• d
• week
• month
• year

• Hz
• mHz
• kHz
• MHz
• GHz
• THz
• rpm
• deg/s
• rad/s

• m/s
• km/h
• m/h
• knot
• ft/s

• s/m
• min/km
• s/ft
• min/km

• Pa
• hPa
• kPa
• MPa
• bar
• torr
• psi
• ksi

• b
• Kb
• Mb
• Gb
• Tb
• B
• KB
• MB
• GB
• TB

• lx
• ft-cd

• ppm
• ppb
• ppt
• ppq

• V
• mV
• kV

• A
• mA
• kA

• W
• mW
• kW
• MW
• GW

• VA
• mVA
• kVA
• MVA
• GVA

• VAR
• mVAR
• kVAR
• MVAR
• GVAR

• Wh
• mWh
• kWh
• MWh
• GWh
• J
• kJ

• VARh
• mVARh
• kVARh
• MVARh
• GVARh

• deg
• rad
• grad
• arcmin
• arcsec

• c
• mC
• μC
• nC
• pC

• N
• kN
• lbf

• g (g-force)
• m/s2

Adding new measurement sets is easy. Take a look at lib/definitions to see how it's done.

Copyright (c) 2013-2017 Ben Ng and Contributors, http://benng.me

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.