Education & Student
Ohms Law Calculator
Ohms Law — it applies Ohm's law V = I × R (and power P = V × I) to the two quantities you provide. This page runs that same calculation on your numbers, in your browser: no signup, no uploads, nothing stored.
Ohms Law Calculator turns your two values and what to solve for into the missing voltage, current, resistance or power using V = I × R (and P = V × I). The maths runs locally, so nothing you enter leaves the page.
About this calculator
Get ohms law right and the rest of the task gets easier. It applies Ohm's law V = I × R (and power P = V × I) to the two quantities you provide. It matters when grades, percentages or averages decide a next step and hand arithmetic is error-prone. Ohm's law: 12 V across 4 Ω draws I = 12 ÷ 4 = 3 A , dissipating P = 12 × 3 = 36 W. The tool above does the same computation in your browser — free, private, nothing stored.
How to use
- Choose which quantity to solve for: V, I, or R.
- Enter the first value.
- Enter the second value.
- Press Calculate to read the result.
Why use Ohms Law Calculator
Fast
Calculations run in your browser. No round trip to a server.
Private
Your inputs never leave your device. Nothing is uploaded.
Free
No signup, no paywall, no ads-in-results, no watermarks.
Accurate
Uses standard formulas for quick educational estimates; check critical results before relying on them.
Mobile-ready
Optimised for phones, tablets, and desktops alike.
Transparent
Honest disclaimers wherever browser limits or regional rules apply.
Common uses
Use it for quick what-if calculations
Use it when comparing two scenarios
Use it for tutoring and study groups
Use it for cross-checking a measurement
Use it when checking a homework answer
Use it before a practical assessment
Technical notes
Ohms Law Calculator applies Ohm's law V = I × R (and power P = V × I) to the two quantities you provide.
Results assume ideal conditions and consistent units, so convert your inputs to the units shown before calculating.
The tool works offline once loaded, since every computation is client-side.
FAQ
What do Value 1 and Value 2 mean?
They depend on what you solve for: for V you enter current then resistance; for I you enter voltage then resistance; for R you enter voltage then current.
What is Ohm's law?
It states V = I × R, linking voltage, current, and resistance in a simple circuit.
Why must resistance or current be positive when dividing?
Solving for current or resistance divides by that value, so it must be greater than zero.
Does the Ohms Law Calculator send my data to a server?
No. The Ohms Law Calculator runs entirely in your browser, so nothing you enter is uploaded, stored, or shared.
Worked example
Ohm's law: 12 V across 4 Ω draws I = 12 ÷ 4 = 3 A, dissipating P = 12 × 3 = 36 W.