Shunt resistor power calculator
The Shunt resistor power calculator computes shunt resistor power from the relation P = I^2 R. It takes 2 inputs (current in A, shunt resistance in ohm) and returns the power dissipated in W. These calculators are for electronics hobbyists, technicians, students and working engineers handling circuit values, and they support decisions such as which component value to fit, whether a stage will behave the way the schematic intends, and what to expect from a circuit before it is built and measured. Enter your values below and the result updates instantly, and you can share a permalink that pre-fills the exact calculation. Unit prefixes are the easiest thing to get wrong, so check the unit each field is labelled with and convert your figure to match it rather than assuming it wants the same prefix as the part marking or the datasheet, and carry enough digits through intermediate steps that early rounding does not distort the final value. For example, with current = 5 A, shunt resistance = 0.1 ohm, the power dissipated works out to 2.5 W, and the worked example further down the page shows every step so you can follow the arithmetic and reproduce it by hand. Units and physical constants follow NIST / IEEE; the relation itself is a standard result of electrical engineering, and the figure above each result carries the date it was last verified. The result assumes ideal components and steady conditions, so it takes no account of tolerance spread, parasitics, temperature drift, supply limits or the power and voltage ratings of the parts you actually fit; treat it as a starting point to check on the bench, not as a finished design, and confirm every part against its rated limits before power is applied.
With Current = 5 A, Shunt resistance = 0.1 ohm, the result is 2.5 W.
Applies to: any numeric inputs. Method source: NIST / IEEE, checked 2026-06-22.
The formula
P = I^2 R
Worked example
With Current = 5 A, Shunt resistance = 0.1 ohm:
- P = I^2 R
- Power dissipated = 2.5 W
This worked example is one of the automated golden-value tests this calculator must pass before it can publish.
What this assumes
- Inputs are real numbers in the units shown.
- The result is the exact value of P = I^2 R; general information, not professional advice.
Frequently asked questions
What formula does this use?
P = I^2 R. This is a standard result of electrical engineering; units and physical constants follow NIST / IEEE.
Does the result ever change over time?
No. This is a pure formula with no external rate, so the same inputs always give the same result.
Official sources and verification
- Method: NIST / IEEE, checked 2026-06-22.
Reviewed by the CalculatorHub team, edited by James Graham, 2026-06-22. See our methodology. General information, not professional advice.