Capacitance Conversion
Unit conversion and basic capacitor code decoding
Required Parameters
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Quick Answer
Capacitance units: 1 F = 10⁶ µF = 10⁹ nF = 10¹² pF. Each prefix step is ×1000. The standard decoupling capacitor is 100 nF (0.1 µF). Capacitor codes like 104 are in picofarads: 10 + 0000 = 100,000 pF = 100 nF.
Capacitance Conversion Calculator
Convert between capacitance units: Farads, millifarads, microfarads, nanofarads, and picofarads.
Conversion
- 1 F = 1,000,000 uF = 1e9 nF = 1e12 pF
- 1 uF = 1,000 nF = 1,000,000 pF
Design Notes
Capacitance unit confusion is one of the most common errors in electronics design. Japanese datasheets prefer nF, American datasheets prefer µF. SPICE simulation uses 'u' for micro and 'm' for milli (not micro!) causing simulation errors.
Common Mistakes
- 1
Using 'm' for micro in SPICE — SPICE 'm' means milli (10⁻³). Use 'u' for micro (10⁻⁶).
- 2
Confusing capacitor code units with resistor code units — capacitor codes are in picofarads.
- 3
Not accounting for DC bias derating when selecting MLCC capacitors — actual capacitance can be 50-70% less than rated.
Knowledge Base
What is 100nF in uF?
0.1 µF. Conversion: divide nanofarads by 1000 to get microfarads. The prefixes: 1 F = 10⁶ µF = 10⁹ nF = 10¹² pF. So 100 nF = 100/1000 = 0.1 µF = 100,000 pF.
How do I convert between pF, nF, and µF?
Each step is ×1000: 1 µF = 1,000 nF = 1,000,000 pF. To go up: divide by 1000. To go down: multiply by 1000. Common equivalences: 0.1 µF = 100 nF = 100,000 pF. 0.01 µF = 10 nF = 10,000 pF. 0.001 µF = 1 nF = 1,000 pF.
What is a farad?
A farad (F) is an enormous amount of capacitance. 1 F stores 1 coulomb of charge per volt. In practice, most capacitors are measured in microfarads (µF), nanofarads (nF), or picofarads (pF). Supercapacitors reach 1-3000 F, but they operate at low voltages (2.5-2.7V).
Why do datasheets use different units?
Convention varies by application: RF circuits use pF (1-100 pF range). Timing and coupling circuits use nF (1-100 nF). Power supply decoupling uses µF (0.1-100 µF). Bulk energy storage uses mF or F. Japanese datasheets often use nF where US datasheets use µF for the same range.
What is the capacitance of a typical decoupling cap?
The standard decoupling capacitor is 100 nF (0.1 µF) ceramic, placed on every IC power pin. Additionally: 1-10 µF bulk decoupling per power group, and 10-100 µF at voltage regulator outputs. For high-speed designs, add 10 nF and 1 nF caps for high-frequency decoupling.
How big is a 1 farad capacitor?
A 1 F electrolytic capacitor at 16V is roughly the size of a soda can (35mm diameter × 60mm). A 1 F supercapacitor at 2.7V is much smaller (about 20mm coin size). The physical size depends on voltage rating, dielectric type, and technology. Higher voltage = larger size for the same capacitance.
What is the standard capacitor value series?
Capacitors follow the same E-series as resistors. E12 (20% tolerance): 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82. E24 (10%): adds intermediate values. Most common values you will encounter: 10, 22, 47, 100, 220, 470 in each decade (pF, nF, µF).
What are millifarads used for?
Millifarads (mF) are uncommon in everyday electronics but appear in: supercapacitor specifications, audio amplifier power supplies (10-100 mF), motor start/run capacitors (50-500 µF = 0.05-0.5 mF), and high-energy pulse applications. Note: some European datasheets use mF instead of µF — always verify the actual value.
How does capacitance relate to charge and voltage?
C = Q / V, where C is capacitance (farads), Q is charge (coulombs), V is voltage (volts). A 1 µF capacitor charged to 5V stores Q = 1×10⁻⁶ × 5 = 5 µC of charge. Doubling the voltage doubles the stored charge (but quadruples the stored energy since E = ½CV²).
What capacitance units are used in SPICE simulation?
SPICE uses base SI units (farads) but accepts engineering notation: 100p = 100 pF, 10n = 10 nF, 1u = 1 µF, 1m = 1 mF. Warning: SPICE uses lowercase 'm' for milli (10⁻³), not micro! To specify microfarads in SPICE: use '1u' not '1m'. This is a very common simulation error.
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