Understanding Multimeter and Oscilloscope Specs

Test equipment specs get thrown around like marketing copy. Here's what the numbers actually tell you.

Multimeters: accuracy class and resolution

A multimeter's accuracy is usually listed as a percentage plus digit count (e.g. ±0.5% + 2 digits) — that's the real precision you get, not the display resolution alone. For general electronics and automotive work, a 3.5 to 4.5 digit meter with basic accuracy is plenty. For calibration or precision lab work, look for true RMS measurement and tighter accuracy specs.

Oscilloscopes: bandwidth and sample rate

Bandwidth tells you the highest frequency signal the scope can measure accurately — as a rule of thumb, buy at least 3-5x the highest frequency you actually need to see, since signal accuracy degrades near the bandwidth ceiling. Sample rate (samples/second) needs to be at least 4-5x your bandwidth to avoid aliasing artifacts. Channel count matters too — 2 channels is fine for basic debugging, 4 channels if you're comparing multiple signals (e.g. digital bus lines).

What actually matters for your bench

• Match bandwidth to your actual signal frequencies, not the highest number available
• True RMS matters if you're measuring non-sinusoidal AC waveforms
• Safety category (CAT rating) matters if you're working on mains-connected or industrial equipment — don't skip this spec

Not sure what spec range fits your bench? Email us what you're measuring and we'll tell you what actually matters.