Calculator that can calculate with units

Question

I'm looking for a calculator

• that can calculate (basic operations +, -, *, / would suffice, more are welcome)
• that can calculate including units (e.g. 2m² + 5000cm²)
• can convert units (e.g. m to ft)
• is gratis
• works on Windows
• starts up quickly and is easy to use

Ideally (but optional)

• is portable

I do not want

• a full-blown mathematics solution like Matlab, Mathematica or similar

Answer 1

I was happy with Phyxcalc for a long time. See another answer recommending Qalculate now.

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I'm happy to have found Phyxcalc.

• Physxcalc can calculate with units, just type them

  4m/s*4.3s
  =17.2m
  
  2m²+5000cm²
  =2.5m²
  

• can convert units with the -> operator

  5W*1yr
  =157784760J
  5W*1yr->kWh
  =43.8291kWh
  
  2m²+5000cm²
  =2.5m²
  2m²+5000cm² -> ft²
  =26.9097760417743ft²
  

• is gratis (freeware, exact license unknown)

• works on Windows 95, 98, XP, Vista and 7 officially.
• works on Windows 10 (Build 10586) on my VM as well.
• startup time is less than 1 second on my second generation Intel i5
• is portable (single executable + a few text files with unit definitions)

• is easy to use: well, at least kind of. Entering formulas are quite straight forward as seen before. However, it starts with a completely empty UI that does not react on F1.

  

  It is possible to show a keypad using the context menu:

  

Answer 2

Not many people seem to be aware, but Windows (10, at least) has some of these functions built in, with its Calculator.

From what I could tell, it doesn't seem to be capable of adding together units natively, but it does have the ability to convert between units, which can assist with calculations at a later stage.

Simply open up Calc(Search in the Start Menu) and click the little burger icon at the top left for many unit options:

Answer 3

Meanwhile I have replaced Phyxcalc with Qalculate, which has more features and a UI that is a bit more self-explanatory.

• it's gratis, GPL 2 license
• it works on Windows 10 x64 1909 (official docs say it works from Vista)
• startup time is ~ 2 seconds
• download size is 51 MB, which is not exactly small. The largest thing about it is a 23 MB Unicode library (libicudt) which gives the nice graphical output.
• the 32 bit version even exists as a portable version

One thing I wanted to change first is the settings to

[x] ignore system language

because it confused my to have the UI in English but enter decimal digits in German.

Let me give the same examples as I did for Phyxcalc:

4m/s*4.3s
=17.2m

2m²+5000cm²
=2.5m²

For year, Phyxcalc uses yr and Qalculate uses year:

5W*1year
=157.788 MJ

Conversion is possible as well, but not that convenient to type (or I did not yet figure out how to type):

And an example where the nice output is a bit more obvious (in dark mode):

Answer 4

Since version 0.12, Speedcrunch supports units as well.

• it is gratis, licensed under GPL
• that can calculate including units (see screenshot below)
• can convert units (see screenshot below)
• works on Windows 10 (I tried, see screenshot below)
• starts up quickly (hardly measureable)
• is also available as a portable version