Engineering work is full of quick checks that do not deserve a spreadsheet: is this stress inside the limit, how much will this bar grow in the sun, what current does this load draw. This calculator for engineers lets you name each value, write the formula as it appears in your notes, and keep units attached to the numbers so a millimeter does not silently become a meter.
Each example shows the answers Notes Calculator gives. Choose Open in Notes Calculator to open one in the web app and change the inputs.
Area with the built-in pi
pi is built in, and a radius in millimeters gives an area in square millimeters that you can convert in the same expression.
| Note | Result |
|---|---|
| radius = 50 mm | 50 mm |
| pi * radius ^ 2 | 7,853.98 mm² |
| pi * radius ^ 2 to cm² | 78.54 cm² |
Stress with SI shorthand
Write large values with k for thousands. A load in newtons over an area in square millimeters gives megapascals.
| Note | Result |
|---|---|
| load = 50k | 50,000 |
| area = 200 | 200 |
| Stress in MPa: load / area | 250 |
Current and power
Ohm’s law with named values: divide the voltage by the resistance for the current, multiply them for the power.
| Note | Result |
|---|---|
| voltage = 240 | 240 |
| resistance = 1.2k | 1,200 |
| current = voltage / resistance | 0.20 |
| Power in watts: voltage * current | 48 |
Thermal expansion
Length times the expansion coefficient times the temperature change gives the growth, and the result can come out in millimeters directly.
| Note | Result |
|---|---|
| length = 12 m | 12 m |
| coefficient = 0.000012 | 1.20e-5 |
| temperature rise = 40 | 40 |
| length * coefficient * temperature rise to mm | 5.76 mm |
For drawings in inches on a metric shop floor, pressure ratings in psi and bar, and tolerance stack-ups, see the engineering unit converter. Number bases and bit math are covered in the hex, binary and octal guide, and how Notes Calculator compares with Soulver, Numi and Parsify is on the comparison pages.
Start free at app.notescalculator.com, or see what Lifetime adds if you want a note per project synced between the office and the lab.