About ZeroAndSpan

ZeroAndSpan is a growing library of free online calculators for instrumentation, process and industrial engineers — the kind of calculations we all do on scrap paper at the calibration bench, done once, done right, and available on any device.

Every tool explains its formula and shows a worked example, so you can verify the math instead of trusting a black box. Where a standard applies (IEC 60751 for RTDs, NAMUR NE 43 for signal limits, ISA practices for calibration), the tools follow it and say so.

The site is built and maintained by an Applied Electronics & Instrumentation engineer. New calculators are added every week — if a tool you need is missing, tell us and it moves to the top of the build list.