Capacitance Converter
Convert farads, microfarads, nanofarads and picofarads — the range that trips up every parts order, where the same capacitor is labelled 0.1 µF, 100 nF or 104 depending on who printed it.
Capacitance Converter
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Nominal values only. Real capacitance varies with DC bias, temperature, frequency and age, and class 2 ceramics can lose more than half their marked value under bias.
- The three-digit code covers values that round to two significant figures in picofarads and does not apply to large electrolytics.
- Energy and charge figures assume an ideal capacitor with no leakage or equivalent series resistance.
In short: Capacitance converts through the farad, one coulomb per volt. The farad is enormous, so real components live in microfarads, nanofarads and picofarads, and the same part is labelled differently by region: 0.1 µF, 100 nF and the code 104 are the same capacitor. All prefix steps are exact powers of ten, so the only real difficulty is keeping track of which one a datasheet is using.
Formula
Each factor is the number of farads in one of that unit. All SI prefix steps are exact powers of ten. The statfarad, confusingly also called the centimetre, comes from the electrostatic CGS system.
Worked Example
- Identify the source factor. One nanofarad is 10−9 F.
- Convert to the SI unit. 100 × 10−9 = 10−7 F.
- Identify the target factor. One microfarad is 10−6 F.
- Divide. 10−7 ÷ 10−6 = 0.1 µF.
- Recognise the part. That is the same component marked 104 on a ceramic disc.
Why one capacitor has three names. A 0.1 µF part is 100 nF is 100,000 pF is marked 104. American schematics have historically preferred microfarads even for small values, European ones nanofarads, and the printed code on the part itself is always in picofarads. None of this is a conversion difficulty — the factors are exact powers of ten — but it causes a great many wrong parts to be ordered, because 100 nF and 100 µF differ by a factor of a thousand and look almost identical in a bill of materials.
Strengths & Limits Of This Model
Where this engine is strong
- Decodes the three-digit marking alongside the conversion, which is where most real confusion lives.
- States explicitly that capacitors combine the opposite way to resistors.
- Shows charge and energy together so the voltage-squared relationship is visible.
Where it stops
- Does not model DC bias derating or temperature coefficient.
- Not a filter or power-supply design calculator.
- Ignores ESR and leakage.
Practical Use Cases
Electronics design and BOM checking
Datasheets, schematics and part markings each favour a different prefix. Converting to one unit before ordering prevents the thousand-fold error.
Power supply and filter design
Smoothing capacitors are specified in microfarads while the ripple calculation may be presented in farads. Both must agree before the sizing is trustworthy.
RF and timing circuits
Oscillator load capacitance and filter values are quoted in picofarads, where stray board capacitance of a few pF is a real part of the total.
Energy storage sizing
Supercapacitors are rated in farads and their usable energy follows E = ½CV² — pair with the Energy Converter to compare against battery figures.
Methodology & Editorial Standards
All conversions route through the farad, the SI unit of capacitance, defined as one coulomb per volt. Every SI prefix step is an exact power of ten. The abfarad and statfarad from the CGS systems are included for legacy literature; the statfarad, which is also confusingly called the centimetre, derives from the exact speed of light and equals about 1.1127 × 10⁻¹² F. Charge and energy figures apply Q = CV and E = ½CV² and require an explicit working voltage. The three-digit marking is decoded in picofarads by the standard convention of two significant digits followed by a decimal exponent. Series and parallel behaviour is shown because capacitors combine in the opposite sense to resistors, which is a persistent source of error. Real capacitance varies with temperature, applied voltage and age, and class 2 ceramics in particular can lose a large fraction of their nominal value under DC bias; this converter handles nominal values only. All conversion factors are exact by definition under the International System of Units, or exact by international agreement where the unit is defined by treaty. Values are held at full IEEE-754 double precision internally and rounded only for display, so chained conversions do not accumulate drift.
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Capacitance Converter — 8 Expert FAQs
8 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
How many nanofarads are in a microfarad?
Exactly 1,000, and there are 1,000,000 picofarads in a microfarad. All prefix steps are exact powers of ten. The practical difficulty is not the arithmetic but the labelling: the same physical part may be printed as 0.1 µF, 100 nF or the code 104, and confusing 100 nF with 100 µF is a thousand-fold error that will not be obvious until the circuit misbehaves.
What does the code 104 on a capacitor mean?
It is read in picofarads: the first two digits are the significant figures and the third is the number of zeroes that follow. So 104 means 10 followed by four zeroes, or 100,000 pF, which is 0.1 µF. Similarly 103 is 10 nF and 105 is 1 µF. The convention only covers values that round to two significant figures, which is why larger electrolytics simply print their value in full.
Why is the farad such a large unit?
Because it is defined as one coulomb per volt, and a coulomb is an enormous quantity of charge. A capacitor of one farad holding one volt stores 6.24 × 10¹⁸ elementary charges. For most of the twentieth century a one-farad capacitor was a laboratory curiosity; supercapacitors have since made them commonplace, but ordinary circuit work still lives in millionths and billionths of a farad.
Do capacitors in series add up like resistors?
No, they behave in the opposite way. Capacitances ADD in parallel and combine as RECIPROCALS in series, which is exactly the reverse of resistors. Two 100 µF capacitors in parallel give 200 µF; in series they give 50 µF. The physical reason is that putting them in series effectively increases the separation between the outer plates.
How much energy does a capacitor store?
Half of the capacitance times the voltage squared. A 470 µF capacitor at 25 V holds 0.147 joules. The square term matters enormously: the same capacitor at 50 V would store four times as much. It also means a large capacitor charged to a high voltage remains genuinely dangerous after the power is removed, which is why bleed resistors exist.
What is a statfarad?
The capacitance unit of the electrostatic CGS system, equal to about 1.1127 × 10⁻¹² F, which is roughly a picofarad. It is also called the centimetre, because in that system capacitance has dimensions of length — an isolated conducting sphere of radius one centimetre has a capacitance of one statfarad. It appears only in older physics texts.
Does a capacitor really have its marked value?
Often not, once it is in circuit. Class 2 ceramic dielectrics such as X7R and especially Y5V lose a substantial fraction of their capacitance under DC bias, sometimes more than half at rated voltage, and they also drift with temperature and age. Electrolytics have wide tolerances to begin with, frequently −20% to +80%. This converter handles nominal values; the datasheet curve tells you the real one.
What is the RC time constant?
The product of resistance and capacitance, in seconds, and it is the time the capacitor takes to reach about 63% of its final voltage. A 470 µF capacitor through 10 kΩ gives 4.7 seconds. Five time constants is conventionally treated as fully charged. This is the basis of most simple timing and filtering behaviour.