# Ohm's Law & Power Law Calculator

> Utilities

Canonical page: [https://chrome-stats.com/d/id592763080](https://chrome-stats.com/d/id592763080)

## Overview

- **ID:** `id592763080`
- **Platform:** Apple
- **Type:** Apple app
- **Status:** Available
- **Publisher:** Cressall Resistors Ltd
- **Category:** Utilities
- **Rating:** 4.40 / 5 (27 ratings)
- **Version:** 1.7
- **Last updated:** 2017-06-12
- **First published:** 2013-01-16
- **Size:** 1.49 MB
- **Data as of:** 2026-09-05
- **Store listing:** [Apple App Store](https://apps.apple.com/us/app/ohms-law-power-law-calculator/id592763080)

## Description

Ohm's law and the power law describe the relationship between the following four electrical entities:

Entity..............Unit.......Symbols

Voltage..........Volts......V
Current..........Amps.....A, I
Resistance...Ohms.....Ω, R
Power.............Watts.....W
 
Ohm's law: Voltage = Current x Resistance
Power law: Power   = Voltage x Current 

Set any two, and the other two can be calculated.

This application allows you to continually lock one parameter and input another, enabling rapid "what-if" recalculation.

Use the keypad to enter a value then tap on the parameter you want to set. It is now fixed, as shown by the padlock symbol.  

 Enter another parameter and the remaining two are calculated.  The most recently entered parameter becomes the new fixed one. 

You can alter which parameter is fixed by tapping it when the input box is empty, or by dragging the padlock to it.

You can 'Freeze' a parameter with a long press until it changes colour. Now alter any of the other three as required. To unfreeze, with the input box empty, tap any other parameter.

The value of the fixed parameter may not be changed. If you attempt to do so, the padlock will flash. In this case, fix another parameter first.

Available in the following Languages:
English, French, German, Swedish, Russian, Polish, Spanish, Italian, Chinese (Traditional & Simplified).

* * * * * * * * * * * * * * * * * * * * * * *

If you find any errors, or have any suggestions, please email us the details & we will address them!

support@cressall.com

## Rankings

- #224,775 — Overall

## Review summary

Most reviews praise the app as a practical, simple tool for Ohm's and Power Law calculations in real-world scenarios (vehicles, RVs) and for homework help. Repeated concerns focus on broken value-locking/input handling (second inputs overwrite or swap the first), data retention issues after updates, a clumsy interface, and limited usefulness for microamp-range circuits.

### Pros

- Very practical for real-world vehicle electrical calculations (cars, motorcycles, boats, RV battery loads, inverter efficiency).
- Simple, straightforward, easy-to-use calculator; does the math with minimal effort.
- Helpful for homework and studying (noted by users as aiding college work).
- Generally reliable and uncluttered, with straightforward results.

### Cons

- Value locking/holding input values is broken; entering a second value overwrites or swaps the first.
- Input management can be buggy; locking features and data retention sometimes fail after updates.
- Interface is clumsy or not very user-friendly.
- Not suitable for microamp-range currents; limited for low-current use.

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Source: [Chrome-Stats](https://chrome-stats.com/d/id592763080)