What Is a 100nF Capacitor and How Do You Choose the Right One

Published Sep 29, 2026, updated Sep 29, 2026

13 min

What Is a 100nF Capacitor?
How to Read 100nF Capacitor Marking: 104, 0.1 µF, and Unmarked SMD Parts
What Is a 100nF Capacitor Used For?
100nF Capacitor Types: Ceramic, Film, and Electrolytic
How to Choose a 100nF Capacitor
Can You Replace a 100nF Capacitor with a Different Value?
100nF Capacitors in JLCPCB PCB Assembly
Conclusion
FAQs About the 100nF Capacitor

Key Takeaways

Value: A 100nF capacitor has a nominal capacitance of 0.1 µF, or 100,000 pF, and all three names describe the same part value.
Marking: Many through-hole ceramic and film capacitors use the three-digit code 104, while most SMD MLCCs are unmarked.
Main use: Its most common function is local decoupling at an IC power pin, where it supplies fast transient current and shunts high-frequency noise to ground.
Default choice: For general decoupling, an X7R or X5R MLCC is a common starting point; 0402 and 0603 are widely used package sizes.
Selection rule: Choose the dielectric, voltage rating, and package together, because a Class 2 ceramic capacitor can lose a significant share of its capacitance under DC voltage.

A 100nF capacitor is a 0.1 µF capacitor, usually marked 104 on leaded parts. It is the capacitor most often placed beside the power pins of an integrated circuit, and it is also used for signal coupling, noise filtering, and RC timing.

The same nominal value can behave differently depending on its dielectric, voltage rating, and package, so a part chosen by capacitance alone may deliver less effective capacitance than the schematic indicates.

In this guide, you will learn:

What a 100nF capacitor is and how its value converts between nF, µF, and pF
How to read the markings on ceramic and film 100nF capacitors
Where 100nF capacitors are used and why the value is so common
How to choose the type, dielectric, voltage rating, and package

100nF capacitors

Figure: 100nF capacitors in 0402, 0603, and 0805 MLCC, ceramic disc, and box packages.

What Is a 100nF Capacitor?

A 100nF capacitor is a capacitor with a nominal capacitance of 100 nanofarads, which equals 0.1 microfarad (µF) or 100,000 picofarads (pF).

100 nF and 0.1 µF are equivalent notations for the same nominal capacitance. Both appear commonly in schematics, datasheets, and BOMs.

Notation	Value	Where You See It
Nanofarads	100 nF	Schematics, BOMs, and European datasheets
Microfarads	0.1 µF	US datasheets, reference designs, and film capacitor bodies
Picofarads	100,000 pF	The base unit behind the three-digit code
Three-digit code	104	Leaded ceramic and film capacitor bodies
Letter as decimal point	100n or u1	Schematics and small capacitor bodies

Capacitance alone does not describe the part. When selecting a 100nF capacitor, five key parameters are typically considered:

Capacitance: 100nF, often written as 104 in the part number
Tolerance: typically ±5%, ±10%, or ±20%
Voltage rating: the maximum continuous DC voltage
Dielectric: C0G, X7R, X5R, or Y5V for multilayer ceramic capacitors (MLCCs)
Package: the case size, such as 0402 or 0603

How to Read 100nF Capacitor Marking: 104, 0.1 µF, and Unmarked SMD Parts

The most common 100nF capacitor code is 104. The first two digits are the significant figures, and the third digit is the number of zeros, with the result in picofarads: 10 followed by four zeros gives 100,000 pF, or 100nF.

100nF capacitor markings

Figure: 100nF capacitor markings on a ceramic disc, a film capacitor, and an SMD reel.

A suffix letter after the code gives the tolerance, and a prefix on film capacitors gives the voltage rating:

Marking	Where It Appears	Meaning
104	Ceramic disc and leaded MLCC	100,000 pF = 100nF
104J, 104K, 104M	Ceramic and film bodies	100nF with ±5%, ±10%, or ±20% tolerance
104Z	Low-cost ceramic discs	100nF with −20% to +80% tolerance
2A104J	Film capacitors	100 V rating (2A), 100nF, ±5%
0.1 or .1	Box and dipped film capacitors	0.1 µF
u1 or 100n	Small film bodies and schematics	0.1 µF, with the letter in place of the decimal point
No marking	SMD MLCCs	Identify from the reel label, part number, or BOM

Ceramic chip capacitors usually carry no printed value, so a 100nF MLCC is identified from its reel label, manufacturer part number, or BOM, as our guide to SMD capacitor codes explains.

What Is a 100nF Capacitor Used For?

A 100nF capacitor is used mainly for local decoupling. It sits between an IC power pin and ground, supplies the fast current pulses that switching logic draws, and shunts high-frequency noise away from the supply rail.

Common 100nF capacitor uses include:

Decoupling at IC power pins: One 100nF capacitor per power pin is a common starting point, placed as close to the pin as practical.
Filtering: In RC and LC filters, it sets the corner frequency together with the resistor or inductor, for example, on ADC inputs and sensor lines.
AC coupling: In series between two stages, it blocks the DC level and passes the signal. With a 10 kΩ load, the cutoff frequency is about 159 Hz.
Reset and debounce circuits: With a pull-up resistor, it sets the delay on the MCU reset pins and switch inputs. A 10 kΩ resistor and 100nF give a 1 ms time constant.
Snubbers and EMI suppression: Film 100nF capacitors are used in RC snubbers across relay contacts and, as safety-rated parts, across AC mains inputs.

Why Is 100nF Commonly Used for Decoupling?

At 1 MHz, an ideal 100nF capacitor has a reactance of about 1.6 Ω, and at 10 MHz, about 0.16 Ω. This low impedance across the frequency range of digital switching noise is one reason 100nF became the standard local decoupling value.

impedance of a real 100nF capacitor

Figure: Impedance of a real 100nF capacitor.

Frequency	Reactance of an Ideal 100nF Capacitor
100 kHz	15.9 Ω
1 MHz	1.59 Ω
10 MHz	0.16 Ω

A real capacitor also has equivalent series inductance (ESL) from its package, pads, and vias. At its self-resonant frequency, the capacitive and inductive reactances cancel, and the impedance reaches its minimum. Above that frequency, the ESL dominates, and the impedance rises again.

With about 1 nH of total mounted inductance, a 100nF capacitor resonates near 16 MHz. The actual frequency depends on the package, pad layout, and via placement, so check the manufacturer's impedance curve for the exact part.

100nF decoupling capacitor

Figure: 100nF decoupling capacitor placed beside an IC power pin with a short via to ground.

Because the impedance of a 100 nF capacitor increases at lower frequencies (15.9 Ω at 100 kHz), designs often pair it with a 1 µF to 10 µF bulk capacitor on the same rail.

Our decoupling capacitor guide covers layout placement and value combinations in detail.

100nF Capacitor Types: Ceramic, Film, and Electrolytic

Most 100 nF capacitors are multilayer ceramic capacitors (MLCCs) because they offer compact size and low ESL for this value. Film capacitors are preferred when stability, low losses, or a mains safety rating is more important

Type	Polarity	Size at 100nF	Strengths	Typical Use
SMD multilayer ceramic (MLCC)	Non-polarized	0201 to 1206	Small, low ESL, and low cost	Decoupling, filtering, and general SMT designs
Ceramic disc or leaded MLCC	Non-polarized	Through-hole	Easy hand assembly	Breadboards and through-hole boards
Polyester (PET) film	Non-polarized	Larger box or dipped body	No DC bias loss, lower distortion than Class 2 ceramic	Audio coupling and general through-hole circuits
Polypropylene (PP) film	Non-polarized	Larger than PET	Very low loss and high stability	Snubbers, precision filters, and timing
Safety-rated film (X2)	Non-polarized	Large box	Certified for mains connection	Across-the-line EMI filters
Aluminum electrolytic or tantalum	Polarized	Larger than an MLCC	Generally not preferred for 100nF applications because MLCCs are typically smaller and have lower ESL	Legacy designs

How to Choose a 100nF Capacitor

Choosing a 100nF capacitor comes down to four variables: dielectric, voltage rating, package size, and tolerance.

The dielectric and voltage rating matter most because together they determine how much capacitance remains at the operating voltage and temperature.

mlcc capacitance change vs temperature graph

Figure: Capacitance change with temperature for 100nF C0G, X7R, X5R, and Y5V dielectrics.

Dielectric: C0G, X7R, X5R, or Y5V

Ceramic capacitor types include Class 1 and Class 2 dielectrics:

Class 1 (C0G, also called NP0): Stable over temperature and voltage, with low dielectric losses.
Class 2 (X7R, X5R, and Y5V): Provides higher capacitance per unit volume, but capacitance varies with temperature, DC voltage, and aging.

Dielectric	Class	Temperature Range	Temperature Characteristic	Best 100nF Use
C0G (NP0)	1	−55 to +125 °C	0 ±30 ppm/°C	Timing, filters, and oscillators
X7R	2	−55 to +125 °C	±15%	Decoupling and general use
X5R	2	−55 to +85 °C	±15%	Decoupling in small packages
Y5V	2	−30 to +85 °C	+22% to −82%	Non-critical, cost-driven circuits only

Choose X7R for: decoupling and general-purpose use, especially on boards that run warm.
Choose X5R for: decoupling in 0201 or 0402 packages where the board stays below 85 °C.
Choose C0G for: RC timing, active filters, and oscillator circuits, where the capacitance sets a time or frequency.

Note

Trade-off: A 100nF C0G capacitor is usually larger and more expensive than an X7R part with the same voltage rating. Y5V is usually the smallest and cheapest option, but its wide capacitance swing makes it a poor fit for supply rails.

Voltage Rating and DC Bias

Choose a voltage rating above the highest voltage the capacitor will see, including transients. Then check how much capacitance a Class 2 part keeps at that voltage.

Figure: DC bias reducing the effective capacitance of 100nF X7R capacitors in 0402 and 0805 packages.

X7R and X5R capacitors lose capacitance as the DC voltage across them increases. The loss is typically larger in smaller packages and in parts with a lower rated voltage, so a 100nF 0402 capacitor on a 5 V rail may deliver noticeably less than 100nF.

Rail Voltage	Common 100nF Voltage Rating
1.8 V to 3.3 V	10 V or 16 V
5 V	16 V or 25 V
12 V	25 V or 50 V
24 V	50 V
48 V	100 V

Selection rule: Read the manufacturer's DC bias curve for the exact part number, and choose the voltage rating or package that keeps enough capacitance at your rail voltage. Most major MLCC manufacturers publish these curves in online selection tools.

Package Size

The package sets the board area, the available voltage ratings, and part of the capacitor's ESL. 0402 and 0603 are the most common choices for 100nF decoupling on SMT boards.

Package (Imperial and Metric Code)	Nominal Size	Commonly Available 100nF Ratings	Typical Use
0201 (0603 metric)	0.6 × 0.3 mm	6.3 V to 16 V	Dense BGA fanout, wearables, and phones
0402 (1005 metric)	1.0 × 0.5 mm	10 V to 50 V	Most compact digital boards
0603 (1608 metric)	1.6 × 0.8 mm	16 V to 100 V	General SMT designs are easier to rework
0805 (2012 metric)	2.0 × 1.25 mm	16 V to 100 V	Higher voltage with lower DC bias loss
1206 (3216 metric)	3.2 × 1.6 mm	50 V to 250 V	Higher-voltage rails and snubbers

Exact ranges vary by manufacturer, so confirm the rating in the part datasheet. Our guide to SMD capacitor sizes lists the body dimensions for each package.

Trade-off: A smaller package saves area and can sit closer to the power pin, but it typically offers lower voltage ratings and a larger DC bias loss.

100nf mlcc package sizes

Figure: 100nF MLCC package sizes from 0201 to 1206 shown at the same scale.

Tolerance

Tolerance matters mainly where the capacitance sets a frequency or time.

Choose ±10% (K) or ±20% (M) for: decoupling, usually in X7R or X5R.
Choose ±5% (J) or tighter for: RC timing and filters, usually in C0G or film.

Can You Replace a 100nF Capacitor with a Different Value?

Whether you can replace a 100nF capacitor depends on its function in the circuit. In decoupling, the IC datasheet's recommended value comes first.

In timing, filter, and coupling circuits, the value sets a time constant or frequency, so a change needs a new calculation.

Situation	Replacement
Decoupling at an IC power pin	Keep 100nF unless the IC datasheet specifies otherwise; adding 1 µF to 10 µF in parallel for bulk is common
RC timing, reset delay, or debounce	Same value; a different value changes the delay in proportion
RC or LC filter	Same value, or recalculate the corner frequency
AC coupling	A larger value lowers the cutoff frequency; a smaller one raises it
Same value, higher voltage rating	Acceptable if it fits the footprint; it often reduces DC bias loss
Same value, different dielectric	Only if the circuit tolerates the new temperature and DC bias behavior
Mains EMI filter position	Only a part of the same safety class (X for line-to-line, Y for line-to-ground) with an equal or higher voltage rating

100nF Capacitors in JLCPCB PCB Assembly

JLCPCB SMT assembly supports passive packages down to 01005 for Standard PCBA and 0402 for Economic PCBA, which covers the usual 100nF decoupling sizes.

The JLCPCB Parts Library lists common 100nF ceramic capacitors. For example, C14663 is a 0603, 50 V, X7R part (YAGEO CC0603KRX7R9BB104) listed as a Basic part.

Before finalizing your BOM, confirm that each part number matches the dielectric, voltage rating, and package your design needs, not only the 100nF value.

Conclusion

A 100nF capacitor is a 0.1 µF capacitor, usually marked 104 on leaded parts, and its main role is local decoupling at IC power pins. For most boards, an X7R or X5R MLCC in 0402 or 0603 is the right starting point, while C0G or film suits circuits where the value sets a time or frequency.

Choosing the dielectric, voltage rating, and package together keeps the effective capacitance at your operating voltage close to the value on the schematic. Once your design is ready, upload your files to JLCPCB to review assembly options and get an instant quote.

FAQs About the 100nF Capacitor

Is 100nF the Same as 0.1 µF?

Yes. 100nF, 0.1 µF, and 100,000 pF are the same capacitance written in different units, and the three-digit code for this value is 104.

What Does 104 Mean on a Capacitor?

It means 100,000 pF, or 100nF. The first two digits give 10, and the third digit adds four zeros, resulting in picofarads.

Does a 100nF Capacitor Have Polarity?

Usually not. Ceramic and film 100nF parts are non-polarized and can be fitted either way, while the uncommon electrolytic and tantalum versions are polarized.

Can I Use a 1 µF Capacitor Instead of 100nF?

Only in some circuits. For decoupling, a 1 µF MLCC often works if the IC datasheet allows it, but in timing, filtering, and coupling circuits, it changes the time constant or cutoff frequency.

Why Do Circuits Pair 100nF with a 10 µF Capacitor?

The 100 nF part handles higher-frequency noise near the IC, while the 10 µF part supplies charge at lower frequencies. Together, they keep the supply impedance low over a wider frequency range.