RC Time Constant Calculator
Calculate tau and the approximate five-time-constant interval for an RC circuit.
Result
Complete the fields to calculate.
Formula and method
τ = R × C
Important assumptions
In an ideal RC circuit, after 5τ the transition exceeds approximately 99%.
Frequently asked questions
Does the calculation run locally?
Yes. Values are processed in your browser and are not sent to a server.
Can I use it for a real installation?
Use it as an educational reference and verify components, tolerances, safety, and applicable code with technical documentation or a qualified person.
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