Calculator
Ohm's law, dividers, LED resistors and more
Pick a preset, fill in the labelled inputs, and read the answer. Presets are free.
iOS and Android, beta this winter.
What is included
- Ohm's law and power: enter any two of V, I, R, P and get the other two
- Series and parallel: R, C and L, with n inputs
- Voltage divider: Vout from Vin, R1 and R2, or R2 for a target Vout
- LED series resistor: supply V, LED Vf and current give R and power, with the nearest E12 or E24 value
- RC: time constant τ and cutoff frequency fc
- dB: voltage ratio, power ratio, and dBm to W and back
- Deviation: % error of measured against nominal, and imbalance % of three values, for example motor windings
- Unit converter: prefixes, °C, °F and K, W and dBm, A·h and W·h at a given V
Formula shown, hints inline
Each preset shows its formula, for example V = I × R. Missing or invalid inputs get an inline hint, never an exception.
Fill from your meter
Presets take values from the readings strip. See Cal Box.
What it does and doesn't do (yet)
| What it does | Plan |
|---|---|
| Presets for Ohm's law and power, series and parallel, dividers, LED resistors, RC, dB and unit conversion. | Free |
Not yet, or not planned
- Formulas reference the current run only; no cross-run analytics.
Questions
Which presets are included?
Ohm's law and power, series and parallel (R, C, L), voltage divider, LED series resistor, RC, dB, deviation and imbalance, and a unit converter.
Does the LED preset pick an E12/E24 value?
It gives R and power, with the nearest E12 or E24 value.
Coming to iPhone and Android.
iOS and Android, beta this winter.
Questions or a meter to suggest? Mail support@testnmeasure.app.
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