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Disclaimer
What our calculators assume, where those assumptions stop applying, and why safety comes first.
Electricity is dangerous. Contact with live conductors can cause serious injury or death, and faults in wiring can cause fire. Nothing on this site should be treated as instruction to carry out electrical work. Always isolate a circuit before working on it, verify it is dead with a suitable tester, and involve a qualified electrician for anything beyond low-voltage bench experimentation.
Educational Purpose
Ohms Law Wheel exists to explain electrical relationships and to perform standard calculations quickly. Its content is general and educational. It is not a design service, an inspection service or a substitute for professional judgement, and it cannot take account of the specific conditions of your circuit, installation or location.
Calculations Are Estimates
Every calculator here implements a simplified model, and each one states the assumptions it relies on. Common simplifications across the site include:
- Components are treated as ideal, linear and at constant temperature.
- Resistivity, forward voltage and similar constants are typical published values, not the specification of the part you actually hold.
- AC results assume resistive loads. Reactance, impedance and power factor are not modelled.
- Voltage drop and conductor calculations ignore skin effect, grouping, ambient temperature and installation method.
- Component tolerances are not applied unless a calculator says otherwise, so real measured values will differ.
Treat every output as a first-pass engineering estimate to be verified by measurement, by datasheet, or by a qualified person.
Not a Substitute for Codes and Standards
Electrical installation is governed by codes and standards that vary by country and often by region. Requirements for conductor sizing, ampacity, protection, earthing, derating and permitted voltage drop come from those documents and from the authority having jurisdiction, not from this website. A result that satisfies a calculation here may still be non-compliant where you are working.
Component and Manufacturer Data
Typical values are used where a datasheet figure is unavailable, for example a nominal LED forward voltage or a standard resistivity. Real components vary. Where a manufacturer publishes a figure for the part you are using, that figure takes precedence over anything calculated here.
Demonstration Content
The review cards displayed on the homepage are illustrative placeholder content included to demonstrate the page layout. They are not verified customer testimonials, the names and locations shown are not those of real individuals, and no aggregate rating is published or implied.
No Warranty and No Liability
This site and its calculators are provided as-is, without warranty of any kind, express or implied, including any warranty of accuracy, fitness for a particular purpose or non-infringement. To the fullest extent permitted by law, the site operator accepts no liability for any loss, damage or injury arising from use of this site or reliance on its results.
External Content
Links to other websites are provided for convenience only. We do not control and are not responsible for the content or accuracy of any external site, and a link does not constitute an endorsement.
Further detail is set out in our terms and conditions and privacy policy.
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Solve for voltage, current, resistance or power from any two known values.