Numbat — The Complete Guide: A Free Scientific Calculator That Checks Your Units
Numbat is a scientific calculator and small scripting language in which every number carries a unit. Type 12 kN times 3.5 m and you get a moment in kN·m; try to add metres to seconds and you get an immediate error. It runs in the browser with nothing to install, and on the command line on Windows, macOS and Linux.
Numbat
David Peter
A scientific calculator and scripting language with full unit checking: quick hand calculations without unit errors, in the browser or on the desktop.
Get it from the vendorWhat you get
- Dimension checking — every calculation is checked, and a unit error is stopped before it reaches the result.
- Unit conversion — SI, imperial units and prefixes, with conversion to any unit you ask for.
- Physical constants — common constants ready to use.
- Functions and variables — define a formula once and reuse it.
- Script files — save a whole calculation as a text file you can review and run again.
Where it helps
In quick checks: the load on a beam, the flow in a pipe, the power of a motor. A student sees at once when a formula is dimensionally wrong, and an engineer skips manual conversions between psi and MPa. For a documented calculation with formulas and sketches for a report, a calculation-sheet tool is a better fit.
Related tools
For a desktop calculator with units and a graphical interface — Qalculate!. For an engineering worksheet with written formulas — SMath Studio. For documented calculations in the browser — EngineeringPaper.xyz.
Qalculate!
Hanna Knutsson
A smart desktop calculator — full unit conversion, physical constants, uncertainty propagation and symbolic algebra.
Get it from the vendor
EngineeringPaper.xyz
Engineering Paper LLC
An engineering calculation sheet in the browser with automatic unit checking and conversion, equation solving and plots.
Get it from the vendor
handcalcs
Connor Ferster
Turns Python calculations in Jupyter into hand-calc style sheets — formula, substituted values and result, in LaTeX.
Get it from the vendorThe bottom line
Numbat is a small, handy safety net against unit errors in everyday calculations. Open source and completely free, including for commercial use.