Capacitor Value Guide: Understanding µF, pF, and nF Ratings

If you’ve ever picked up a ceramic disc capacitor marked “104” and wondered what that actually means, or tried to order a 0.1 µF Capacitor only to find the distributor lists it as 100 nF, you’ve run into the most common source of confusion in electronics. Capacitor values are expressed in three different sub-units of the Farad, and converting between them trips up hobbyists and working engineers alike.

I’ve been designing PCBs for over a decade, and I still keep a conversion chart pinned above my workbench. The problem isn’t that the math is hard — it’s just three zeros at a time. The problem is that schematics, component markings, distributor listings, and datasheets all use different conventions, and one misplaced decimal point means a circuit that doesn’t work.

This guide covers everything you need to work confidently with capacitor values: the unit system, conversion between µF, nF, and pF, how to read markings on physical components, the standard E-series values you’ll actually find in stock, and practical guidance on which values to use for common circuit applications.

How Capacitor Values Are Measured

Capacitance measures a component’s ability to store electrical charge. The base unit is the Farad (F), named after Michael Faraday, but a single Farad represents an enormous amount of capacitance. For perspective, a 1 Farad capacitor charged to 1 volt stores 1 coulomb of charge — roughly the amount of charge that flows through a 100W light bulb in about two seconds.

In practical electronics, we work with fractions of a Farad that are almost absurdly small compared to the base unit. The three sub-units you’ll encounter daily are microfarads, nanofarads, and picofarads, each separated by a factor of 1,000.

Microfarads (µF)

A microfarad is one millionth of a Farad (10⁻⁶ F). This is the largest unit commonly used in circuit design and the one you’ll see printed on electrolytic capacitors, tantalum capacitors, and larger film capacitors. Typical values range from 0.1 µF for small ceramic decoupling caps up to tens of thousands of µF for power supply filtering electrolytics.

On older components and schematics, you might see µF written as uF, mfd, MFD, MF, or even UF. These all mean the same thing. The “mfd” notation is particularly confusing because it looks like it should mean “millifarad,” but in legacy documentation it always means microfarad.

Nanofarads (nF)

A nanofarad is one billionth of a Farad (10⁻⁹ F), or equivalently, one thousandth of a microfarad. The nanofarad occupies the middle ground between µF and pF and is commonly used for timing circuits, signal coupling, intermediate filtering, and noise suppression.

Nanofarad notation is especially common in European schematics and component catalogs. In North American practice, the nF unit was less popular historically — engineers would write 0.01 µF instead of 10 nF, or 10,000 pF instead of 10 nF. Modern practice has largely standardized on nF for this middle range, but you’ll still encounter both conventions depending on who drew the schematic.

Picofarads (pF)

A picofarad is one trillionth of a Farad (10⁻¹² F), or one millionth of a microfarad. This is the smallest common unit and the one used for RF circuits, oscillator tuning, high-frequency filtering, and any application where tiny amounts of capacitance matter.

Older documentation sometimes uses “mmfd” (micromicrofarad), “MMFD,” “MMF,” “uuF,” or “PF” — all of which mean picofarad. The “micromicrofarad” term makes mathematical sense (micro × micro = 10⁻⁶ × 10⁻⁶ = 10⁻¹²) but has been replaced by the cleaner “picofarad” designation.

Unit	Symbol	Value in Farads	Relationship	Common Applications
Microfarad	µF	10⁻⁶ F	1 µF = 1,000 nF	Power supply filtering, motor run, audio coupling
Nanofarad	nF	10⁻⁹ F	1 nF = 1,000 pF	Signal filtering, timing, decoupling
Picofarad	pF	10⁻¹² F	Base small unit	RF tuning, oscillators, high-frequency circuits

Converting Between Capacitor Value Units

The conversion between µF, nF, and pF follows a simple pattern: each step is a factor of 1,000 (three decimal places). Move the decimal point three places to the right when going from a larger unit to a smaller one, and three places to the left when going from smaller to larger.

Conversion Formulas

To convert from µF to nF: multiply by 1,000. So 0.1 µF × 1,000 = 100 nF.

To convert from nF to pF: multiply by 1,000. So 100 nF × 1,000 = 100,000 pF.

To convert from µF to pF: multiply by 1,000,000. So 0.1 µF × 1,000,000 = 100,000 pF.

Going the other direction, divide instead of multiply. To convert 4,700 pF to nF, divide by 1,000 to get 4.7 nF. To convert that to µF, divide by 1,000 again to get 0.0047 µF.

The trick that experienced engineers use: count the zeros. From µF to nF is three zeros. From nF to pF is three more. From µF to pF is six zeros total. If you can remember “three zeros per step,” you’ll never get lost.

Quick Reference Conversion Table

This table covers the capacitor values you’ll encounter most frequently, showing the same value expressed in all three units along with the common 3-digit marking code used on ceramic capacitors.

µF (Microfarad)	nF (Nanofarad)	pF (Picofarad)	3-Digit Code
0.000001 µF	0.001 nF	1 pF	010
0.0000047 µF	0.0047 nF	4.7 pF	4R7
0.00001 µF	0.01 nF	10 pF	100
0.000022 µF	0.022 nF	22 pF	220
0.000047 µF	0.047 nF	47 pF	470
0.0001 µF	0.1 nF	100 pF	101
0.00022 µF	0.22 nF	220 pF	221
0.00047 µF	0.47 nF	470 pF	471
0.001 µF	1 nF	1,000 pF	102
0.0022 µF	2.2 nF	2,200 pF	222
0.0047 µF	4.7 nF	4,700 pF	472
0.01 µF	10 nF	10,000 pF	103
0.022 µF	22 nF	22,000 pF	223
0.047 µF	47 nF	47,000 pF	473
0.1 µF	100 nF	100,000 pF	104
0.22 µF	220 nF	220,000 pF	224
0.47 µF	470 nF	470,000 pF	474
1 µF	1,000 nF	1,000,000 pF	105
4.7 µF	4,700 nF	4,700,000 pF	475
10 µF	10,000 nF	10,000,000 pF	106

How to Read Capacitor Markings

One of the most practical skills in electronics is reading the markings printed on a physical capacitor to determine its value. Different capacitor types use different marking conventions.

The 3-Digit Code System

Small capacitors like ceramic disc and ceramic multilayer (MLCC) types use a 3-digit code because there isn’t enough space to print the full value. This code works in picofarads, which is important to remember.

The first two digits are the significant figures of the capacitance value. The third digit is the multiplier — it tells you how many zeros to add after the first two digits. The result is always in picofarads.

For example, a capacitor marked “104” decodes as: first two digits are “10,” third digit is “4” meaning add four zeros. So 10 followed by 0000 = 100,000 pF = 100 nF = 0.1 µF.

Another example: “473” means 47 followed by three zeros = 47,000 pF = 47 nF = 0.047 µF.

For very small capacitor values, a two-digit code without a multiplier indicates the value directly in picofarads. A capacitor marked simply “47” is 47 pF. Some capacitors use “R” to indicate a decimal point: “4R7” means 4.7 pF.

3-Digit Code	Calculation	Value (pF)	Value (nF)	Value (µF)
100	10 × 10⁰ = 10	10 pF	0.01 nF	0.00001 µF
101	10 × 10¹ = 100	100 pF	0.1 nF	0.0001 µF
102	10 × 10² = 1,000	1,000 pF	1 nF	0.001 µF
103	10 × 10³ = 10,000	10,000 pF	10 nF	0.01 µF
104	10 × 10⁴ = 100,000	100,000 pF	100 nF	0.1 µF
105	10 × 10⁵ = 1,000,000	1,000,000 pF	1,000 nF	1 µF
221	22 × 10¹ = 220	220 pF	0.22 nF	0.00022 µF
222	22 × 10² = 2,200	2,200 pF	2.2 nF	0.0022 µF
223	22 × 10³ = 22,000	22,000 pF	22 nF	0.022 µF
224	22 × 10⁴ = 220,000	220,000 pF	220 nF	0.22 µF
471	47 × 10¹ = 470	470 pF	0.47 nF	0.00047 µF
472	47 × 10² = 4,700	4,700 pF	4.7 nF	0.0047 µF
473	47 × 10³ = 47,000	47,000 pF	47 nF	0.047 µF
474	47 × 10⁴ = 470,000	470,000 pF	470 nF	0.47 µF

Tolerance Letter Codes

After the 3-digit value code, you’ll often see a letter indicating the capacitor’s tolerance — how much the actual capacitance may deviate from the marked value. Common codes include:

Letter	Tolerance	Typical Use
B	±0.1 pF	Precision RF components
C	±0.25 pF	Precision circuits
D	±0.5 pF	Precision circuits
F	±1%	Precision timing, filters
G	±2%	Precision applications
J	±5%	General purpose, good quality
K	±10%	General purpose
M	±20%	Non-critical applications
Z	-20% / +80%	Very loose tolerance

So a capacitor marked “104J” is 0.1 µF with ±5% tolerance, and “473K” is 47 nF with ±10% tolerance.

Direct Marking on Larger Capacitors

Electrolytic capacitors, tantalum capacitors, and larger film capacitors have enough surface area to print the value directly. You’ll see markings like “47µF 25V” or “1000µF 16V” — the capacitance value followed by the maximum voltage rating.

Some manufacturers use the RKM code system where the unit letter replaces the decimal point. Under this system, “4n7” means 4.7 nF, “1u0” means 1.0 µF, and “p47” means 0.47 pF. This convention is especially common on European-made components and avoids the problem of decimal points disappearing on photocopied schematics.

SMD Capacitor Markings

Surface-mount capacitors present a particular challenge because many smaller packages (0402, 0603) have no markings at all. Larger SMD capacitors (0805 and above) may use the same 3-digit code system as through-hole ceramics, or they may use a letter-digit code that encodes both capacitance and voltage.

For unmarked SMD capacitors, the only reliable way to determine the value is to check the circuit schematic, reference the BOM (bill of materials), or measure the capacitance with a meter. Keeping components in labeled tape or bags during assembly prevents identification headaches later.

Standard Capacitor Values and the E-Series

You might wonder why you can easily find a 4.7 µF capacitor but not a 5 µF. The answer lies in the E-series system of preferred numbers, which standardizes the capacitor values that manufacturers actually produce.

How the E-Series Works

The E-series is a system of logarithmically spaced values that divides each decade (factor of 10) into a set number of steps. The number after the “E” tells you how many values exist per decade. More values per decade means finer granularity and tighter tolerance requirements.

E3 series: 3 values per decade (for ±40-50% tolerance components, like some electrolytics) E6 series: 6 values per decade (for ±20% tolerance) E12 series: 12 values per decade (for ±10% tolerance) E24 series: 24 values per decade (for ±5% tolerance)

Most capacitors you’ll encounter in practice follow the E6, E12, or E24 series. High-precision capacitors may follow E48 or E96, but these are less common.

E6 and E12 Standard Capacitor Values

The E6 series contains six base values per decade: 1.0, 1.5, 2.2, 3.3, 4.7, and 6.8. Multiply these by any power of 10 to get the full range. So for the E6 series in the picofarad range, you’d find 1 pF, 1.5 pF, 2.2 pF, 3.3 pF, 4.7 pF, 6.8 pF, then 10 pF, 15 pF, 22 pF, and so on.

The E12 series adds six more values between the E6 entries: 1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, and 8.2.

E6 Values	E12 Values (includes E6)	E24 Values (includes E12)
1.0	1.0	1.0, 1.1
—	1.2	1.2, 1.3
1.5	1.5	1.5, 1.6
—	1.8	1.8, 2.0
2.2	2.2	2.2, 2.4
—	2.7	2.7, 3.0
3.3	3.3	3.3, 3.6
—	3.9	3.9, 4.3
4.7	4.7	4.7, 5.1
—	5.6	5.6, 6.2
6.8	6.8	6.8, 7.5
—	8.2	8.2, 9.1

Why the E-Series Matters for Design

Understanding the E-series saves time during design. If your calculation calls for a 5 µF capacitor, you won’t find one — the nearest standard values are 4.7 µF (E6/E12) or 5.1 µF (E24). Designing with standard values from the start avoids component sourcing problems later.

The spacing between E-series values is designed so that the tolerance bands of adjacent values overlap or just touch. With ±20% tolerance and E6 values, any actual capacitance value you might need falls within the tolerance range of at least one standard value. This is the fundamental elegance of the preferred number system.

For practical design work, I recommend designing to E12 values whenever possible. E12 gives you enough granularity for most applications, the components are universally stocked by distributors, and the parts are generally less expensive than E24 or higher series components.

Capacitor Values by Application

Knowing which capacitor values to use for common circuit functions is as important as knowing how to read them. Here’s a practical reference based on real-world design practice.

Power Supply Filtering

Bulk filtering capacitors in power supplies typically use large electrolytic or tantalum values: 100 µF, 220 µF, 470 µF, 1,000 µF, or even higher. The rule of thumb is roughly 1,000 µF per amp of output current for linear regulators, though switching supplies have different requirements.

Secondary filtering or output decoupling uses smaller values, typically 10 µF to 100 µF ceramic or tantalum capacitors placed close to the voltage regulator output pins.

IC Decoupling

Every IC power pin needs a decoupling capacitor placed as close as physically possible to the pin. The standard value for general-purpose digital IC decoupling is 100 nF (0.1 µF), which has been the go-to value for decades. For higher-speed digital circuits, adding a smaller capacitor in parallel (such as 10 nF or 1 nF) helps suppress higher-frequency noise.

Many designers also place a bulk decoupling capacitor of 10 µF or 47 µF near groups of ICs to provide a local charge reservoir.

Timing Circuits

RC timing circuits (using resistors and capacitors together) require specific capacitor values calculated from the desired time constant. Common timing capacitor values range from 1 nF to 10 µF depending on the timing period required. For 555 timer circuits, values of 10 nF, 100 nF, and 1 µF are frequently used.

Precision timing applications demand capacitors with tight tolerance (±5% or better) and stable temperature characteristics. NP0/C0G ceramic capacitors or polypropylene film types are preferred over standard X7R or Y5V ceramics, whose capacitance varies significantly with temperature and applied voltage.

Audio Circuits

Audio coupling capacitors block DC while passing AC audio signals. Typical values range from 100 nF to 10 µF depending on the impedance of the circuit and the lowest frequency that needs to pass through. Higher-impedance circuits need larger coupling capacitors to maintain low-frequency response.

Audio filter circuits use values calculated from the desired crossover or cutoff frequencies. Film capacitors (polypropylene or polyester) are preferred in audio signal paths for their low distortion characteristics.

RF and High-Frequency Circuits

Radio frequency circuits use picofarad-range capacitors, typically 1 pF to 100 pF, for tuning, impedance matching, and filtering. At these frequencies, even the parasitic capacitance of PCB traces and component leads matters, so precise capacitor values and careful layout are essential.

NP0/C0G ceramic capacitors are the standard choice for RF applications due to their excellent stability across temperature and voltage.

Application	Typical Value Range	Recommended Type	Tolerance
Power supply bulk filter	100-10,000 µF	Electrolytic, Tantalum	±20% OK
IC decoupling	100 nF (+ 10 nF)	Ceramic MLCC (X7R)	±10-20%
Timing circuits	1 nF – 10 µF	Film or NP0 ceramic	±5% or better
Audio coupling	100 nF – 10 µF	Film (polypropylene)	±5-10%
Audio filters	1 nF – 1 µF	Film (polypropylene)	±5% or better
RF tuning/matching	1-100 pF	NP0/C0G ceramic	±5% or better
Motor run	1-80 µF	Metallized polypropylene	±5-10%
EMI suppression	1 nF – 100 nF	Ceramic (Y-rated for safety)	±20% OK

Understanding Capacitor Voltage Ratings

While this guide focuses on capacitance values, voltage rating is the other critical specification. Every capacitor has a maximum voltage it can safely withstand, and exceeding this rating causes the dielectric material to break down, potentially destroying the capacitor.

Standard voltage ratings follow their own series of preferred values: 6.3V, 10V, 16V, 25V, 35V, 50V, 63V, 100V, 200V, 250V, 400V, 450V, and 630V are common. Some capacitors also carry letter codes for voltage: 0G = 4V, 0J = 6.3V, 1A = 10V, 1C = 16V, 1E = 25V, 1H = 50V, 2A = 100V, and so on.

The safe practice is to select a capacitor with a voltage rating at least 50% higher than the maximum voltage it will see in the circuit. A 5V rail should use at least a 10V rated capacitor, and preferably 16V or 25V for extra margin. This derating extends the capacitor’s life and provides a safety buffer against voltage transients.

Combining Capacitors for Non-Standard Values

Sometimes a design requires a capacitance value that doesn’t match any standard E-series value. Rather than sourcing a custom component, you can combine standard capacitors.

Capacitors in parallel add directly: two 4.7 µF capacitors in parallel give 9.4 µF. This is the most common approach and the easiest to implement on a PCB.

Capacitors in series combine by the reciprocal formula: 1/C_total = 1/C₁ + 1/C₂. Two equal capacitors in series yield half the value of either one. So two 10 nF capacitors in series give 5 nF.

For practical design, parallel combinations are preferred because they’re simpler and increase the total capacitance. Series combinations are rarely used except in specialized high-voltage applications where the voltage is split across multiple capacitors.

Common Mistakes with Capacitor Values

Avoiding these frequent errors saves debugging time and prevents damaged components.

Confusing µF with nF

The most common mistake is misreading 0.1 µF as 0.1 nF or vice versa. These values differ by a factor of 1,000, so getting them wrong causes dramatic circuit malfunctions. A decoupling capacitor that should be 100 nF but is installed as 100 pF provides essentially no filtering. Always double-check conversions, especially when translating between a schematic drawn in one notation and a parts list using another.

Ignoring Voltage Derating in Ceramic Capacitors

Many high-K ceramic capacitors (X5R, X7R, Y5V) lose significant capacitance when DC voltage is applied. A “10 µF” X5R capacitor rated for 16V might only provide 5-6 µF of actual capacitance at 10V bias. This voltage coefficient effect is not reflected in the marked value and can be a significant trap for designers who don’t check the datasheet curves.

Using Wrong Tolerance for the Application

A ±20% tolerance capacitor (M code) is fine for power supply bulk filtering but can cause problems in a precision timing circuit where component values directly affect the output frequency or timing period. Match the tolerance to the application requirements.

Frequently Asked Questions About Capacitor Values

What does the “104” code on a ceramic capacitor mean?

The code “104” follows the standard 3-digit marking system where the first two digits are the significant figures and the third digit is the multiplier (number of zeros to add). So “104” means 10 followed by four zeros: 100,000 pF, which equals 100 nF or 0.1 µF. This is one of the most common capacitor values, used primarily for IC decoupling.

Is 0.1 µF the same as 100 nF?

Yes, they are exactly the same value. Since 1 µF = 1,000 nF, then 0.1 µF = 0.1 × 1,000 = 100 nF. Similarly, 100 nF = 100 × 1,000 = 100,000 pF. The 3-digit code for this value is “104.” You’ll see this same value written in all three formats depending on the source — schematics might show 0.1 µF, component markings might show 104, and distributor listings might show 100 nF.

Why can’t I find a 5 µF or 500 pF capacitor?

Capacitor manufacturers produce components in standardized E-series values, not arbitrary numbers. The standard values near 5 µF are 4.7 µF (E6 series) and 5.1 µF (E24 series, less commonly available). Similarly, near 500 pF you’ll find 470 pF (E6) or 510 pF (E24). Designing with standard E-series values from the start ensures your components are readily available and cost-effective.

What’s the difference between NP0/C0G and X7R capacitor values?

While both might be marked with the same capacitance value, their actual performance differs significantly. NP0/C0G capacitors have extremely stable capacitance across temperature and voltage — the marked value is what you get under all operating conditions. X7R capacitors can vary ±15% with temperature and lose substantial capacitance under DC bias voltage. For applications where the exact capacitor value matters (timing, filtering, oscillators), NP0/C0G is the better choice despite its higher cost and lower maximum capacitance.

Can I replace a capacitor with a different value?

It depends entirely on the application. For power supply decoupling, using a slightly larger value (say 150 nF instead of 100 nF) is generally fine. For timing circuits, filter networks, or oscillators, using a different value changes the circuit’s behavior and can cause it to malfunction. As a general rule: match the original value as closely as possible, use the same voltage rating or higher, and match the capacitor type (ceramic, film, electrolytic) unless you have a specific reason to change it.

Useful Resources for Working with Capacitor Values

Online Calculators and Tools:

• DigiKey Capacitance Conversion Calculator (digikey.com/en/resources/conversion-calculators)
• Circuit Digest Capacitor Code Calculator (circuitdigest.com/calculators)
• ElecCalculator Capacitor Code Decoder (elecalculator.com)

Reference Charts:

• PeterVis.com — Complete E24 standard values conversion chart (pF/nF/µF)
• Electronics-Notes.com — Comprehensive capacitor conversion tables
• RF Cafe — Standard capacitor values and color codes reference

Component Distributors (for sourcing standard values):

• DigiKey (digikey.com) — Extensive parametric search, excellent datasheets
• Mouser Electronics (mouser.com) — Wide selection with detailed filtering
• LCSC (lcsc.com) — Cost-effective source for standard components
• Arrow Electronics (arrow.com) — Professional component sourcing

Technical Documentation:

• Vishay E-Series Values reference (vishay.com)
• IEC 60062 standard (defines E-series preferred numbers)
• Manufacturer datasheets (always the most reliable source for specific parts)

Summary of Key Capacitor Value Relationships

Working confidently with capacitor values comes down to internalizing a few key facts. The three units — µF, nF, and pF — are separated by factors of 1,000. The 3-digit marking code on ceramic capacitors gives the value in picofarads with the third digit as a multiplier. Standard E-series values (especially E6 and E12) define which capacitor values are actually available from manufacturers.

Once these relationships become second nature, you’ll read component markings at a glance, convert between units without hesitation, and select appropriate values for your circuits without constantly reaching for a reference chart. That’s the goal — not memorizing every possible value, but understanding the system well enough that the numbers make intuitive sense.

The capacitor values you’ll use most frequently are surprisingly few: 10 pF, 22 pF, 100 pF for RF work; 1 nF, 10 nF, 100 nF for decoupling and filtering; and 1 µF, 10 µF, 100 µF, 1000 µF for power supply work. Master these common values first, and the rest of the system falls into place naturally.