# Engineering calculations in a tool that will handle units

I know Mathcad handles units along with numbers which makes it easier to avoid errors by tracking units the way we would by hand.

e.g. 250 kW + 500 W


I just wanted to compare tools before I switch to Mathcad. Are there any other tools people are aware of which will handle units as well?

I am especially interested in free / open source alternative that could do this unit-tracking either natively or with a Plugin.

e.g. Python or Jupyter notebooks etc.

If I must go with a paid version then Mathcad (or Mathcad Express, its free cousin) works as well unless there's a paid competitor that had more features or ease of use.

• WolframAlpha and by extension it’s bigger brother Mathematica (now called Wolfram One I think?) can do this Jul 5 '20 at 5:50
• @SolarMike Indeed! I always do this by hand so far but moving to a software like MathCad which can handle this natively seems an improvement from just using Excel and then validating the units by hand. Also in Excel the formula itself remains a bit opaque. Jul 5 '20 at 6:49
• I don't know what you are after next to the units support, but if just need numerical calculations, basic graphing and units this speqmath.com is simple, light and great. Jul 5 '20 at 7:56
• Mathematica incorrectly called wolfram one has many dedicated functions for handling units and can directly numerically solve Jul 6 '20 at 10:06
• I'd echo the importance of knowing dimensional analysis. I'm not sure about this since I don't use it but I seem to recall that the Boost libraries for C++ have ways of enforcing this. Dec 21 '20 at 19:06

If you're interested in using Python, check out the pint, astropy.units or unyt packages. I have personally used pint + jupyter for day-to-day engineering in the past, and have looked at the others and they all should be suitable.

Another great free tool that work very well and its a clone of MathCad (so you won't have to relearn something) is SMath Studio

As I've mentioned up until now its free (although I think its closed source).

If you were using Mathcad before and you liked it, I guarantee that you will love this.

For me, although I work day to day with Python, this is the go to place for me when I want to make a quick calculation and I'm worried about units consistency.

No one seems to have suggested this, but Google search bar handles mixed units just fine. You can type "(25 pounds mass)(7 m/s^2) in dynes" and it'll give it to you. If you don't specify the output it typically defaults to SI. You can even say things like (Planck's constant)*(speed of light)/(700 nm) and it will give you the energy.

Downside is you don't have a nice record of your calculations, but for quick things I use it in my job all the time

There are good and extensive examples using unyt module for Python. Check out this: Working with unyt-unvt v2.8.0 documentation.pdf.

For everyday use, basically as my desktop "pocket" calculator, I use Qalculate!

The look and feel is like a pocket calculator, under the hood it's a computer algebra sytem. It handles units just fine and allows you to force output in a specific unit by typing the calcualtipon you want as an equation, for example you could type a * b / c = x kWh if a * b / c would return a result in J and you want kWh.