How this calculator works
A capacitor stores charge, and its capacitance is the charge stored per volt: one farad holds one coulomb per volt. The farad is a large unit for practical electronics, so components are almost always marked in microfarads (millionths of a farad), nanofarads (thousand-millionths) or picofarads (million-millionths). Each step between these units is a factor of 1,000, which is why a part marked 4n7 means 4.7 nF and a part marked 104 means 100,000 pF or 0.1 µF.
Formula
base = value x F(unit), where F is the capacitance in farads. 1 F = 1,000,000 µF = 1,000,000,000 nF = 1,000,000,000,000 pF. Equivalently, 1 µF = 1,000 nF = 1,000,000 pF and 1 nF = 1,000 pF.
Worked example
A 4.7 µF capacitor is 4.7 x 1,000 = 4,700 nF and 4,700,000 pF. A 100 pF capacitor is 0.1 nF and 0.0001 µF. A 1 F supercapacitor is 1,000,000 µF.
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Frequently asked questions
What does the code 104 mean on a ceramic capacitor?
The first two digits are significant and the third is the number of zeros in picofarads, so 104 means 10 followed by four zeros, or 100,000 pF. That is 100 nF or 0.1 µF.
Why is capacitance measured in farads when components are so much smaller?
The farad is an SI coherent unit, so formulas work without conversion factors. Practical capacitors range from a few picofarads to thousands of microfarads, so prefixes carry the everyday numbers.
Is a millifarad supported here?
Not on this page. Millifarads are uncommon in component marking, so the page lists farads and the three smaller SI prefixes used on parts. Divide a millifarad value by 1,000 to enter it as farads, or multiply by 1,000 to enter it as microfarads.