The 2.2nF capacitor (code 222) explained: decode the marking, choose the right dielectric, calculate RC filter cutoffs, and master PCB layout — engineer’s guide.

If you’ve ever squinted at a tiny ceramic disc stamped with 222 and asked yourself what it means, you’re in good company. The 2.2nF capacitor — marked with the three-digit EIA code 222 — is one of those unassuming components that shows up everywhere: RF snubbers, RC timing loops, ADC anti-aliasing filters, and decoupling rails. It’s not glamorous, but pick the wrong value or the wrong dielectric and your design will tell you loud and clear.

This guide breaks down everything a working PCB engineer needs to know about the 2.2nF capacitor — from reading the code off the body to calculating real cutoff frequencies and integrating the part cleanly into your next layout.

What Does Capacitor Code 222 Mean?

The 2.2nF capacitor carries the EIA three-digit marking 222, decoded as follows:

Digit Position	Value	Meaning
1st digit	2	First significant digit
2nd digit	2	Second significant digit
3rd digit (multiplier)	2	× 10² = × 100
Result	2200 pF = 2.2 nF = 0.0022 µF	All equivalent values

So the math is: 22 × 100 = 2200 pF = 2.2 nF. You’ll sometimes see this part listed as 2200pF in distributor catalogs — same component, different unit preference. If there’s a letter suffix like J (±5%) or K (±10%), that’s the tolerance code. The voltage rating, if encoded, usually appears as a separate prefix (e.g., 2A = 100 VDC per EIA standard).

Worth noting: a 222 and a 223 are not the same thing. The 223 decodes to 22 × 1000 = 22,000 pF = 22 nF — a full 10× larger. Confusing these two on a BOM has caused more than one engineering headache.

2.2nF Capacitor Key Specifications at a Glance

Parameter	Typical Values
Capacitance	2.2 nF (2200 pF / 0.0022 µF)
EIA Code	222
Common Dielectrics	C0G/NP0, X7R, Y5V
Voltage Rating	16V, 50V, 100V, 250V, 400V (type-dependent)
Tolerance	±5% (J), ±10% (K), ±20% (M)
Package (SMD)	0402, 0603, 0805, 1206
Package (TH)	Radial disc, 5mm / 10mm pitch
ESR	Very low (suitable for RF and HF circuits)
Mounting	Polarised? No — fully non-polarised

Dielectric Matters: Choosing the Right 2.2nF Capacitor Type

This is where a lot of engineers get burned. Ceramic capacitors are divided into two broad application classes, and a 2.2nF part comes in both:

C0G / NP0 (Class 1) — Your Best Bet for Precision Work

C0G dielectric has near-zero temperature coefficient and almost no capacitance drift with voltage or age. If your 2.2nF capacitor sits in a timing circuit, an oscillator feedback loop, or any precision analog path, C0G is the non-negotiable choice. It gives you high stability, low loss (high Q), and predictable behaviour across temperature — exactly what resonant circuits and filter poles demand.

X7R (Class 2) — Good for General-Purpose Filtering

X7R offers a ±15% capacitance variation over −55°C to +125°C. It’s far more compact and cheaper than C0G at equivalent values. For bypass, decoupling, and non-precision filter stages where the cutoff frequency doesn’t need to be tight, X7R works fine. Just be aware of DC bias derating — at high DC bias, effective capacitance can drop noticeably.

Y5V / Z5U — Generally Avoid for Signal Paths

High volumetric efficiency, but capacitance can vary by as much as −82% over temperature and voltage. You wouldn’t use this in a filter or timer where predictability matters.

2.2nF Capacitor in RC Timing Circuits

The RC time constant is the foundational equation for any timing application:

τ = R × C

With a 2.2nF capacitor, the time constants you can achieve across standard resistor values look like this:

Resistor (R)	Time Constant (τ = R × C)	Typical Use Case
1 kΩ	2.2 µs	High-frequency pulse timing
10 kΩ	22 µs	Mid-range timing, debounce circuits
47 kΩ	103 µs	Oscillator RC networks
100 kΩ	220 µs	Low-power timer stages
470 kΩ	1.034 ms	Longer interval timing

In a 555 timer charging circuit, the 2.2nF capacitor is commonly paired with resistors in the tens-of-kilohm range to set oscillation frequencies in the tens-of-kilohertz — a sweet spot for tone generation, PWM generation, and clock references in simple microcontroller circuits.

One thing to watch: the time constant defines when the capacitor charges to ~63.2% of supply voltage. Full “charged” is conventionally taken at 5τ (99.3%). For timing accuracy, always use a C0G dielectric and a tight-tolerance resistor (1% metal film minimum).

2.2nF Capacitor in Filter Applications

Low-Pass and High-Pass RC Filter Design

The cutoff frequency formula for an RC filter is:

fc = 1 / (2π × R × C)

With a 2.2nF capacitor, here are the cutoff frequencies you get across common resistor values:

Resistor (R)	Cutoff Frequency (fc)	Filter Application
100 Ω	~723 kHz	RF pre-filter, HF bypass
1 kΩ	~72.3 kHz	Audio anti-aliasing (high end)
7.23 kΩ	~10 kHz	Audio band filter
10 kΩ	~7.23 kHz	ADC input conditioning
72.3 kΩ	~1 kHz	Low-frequency signal separation

At the cutoff frequency, the output signal drops to 70.7% of the input (−3 dB). Below fc for a low-pass, the signal passes through largely unaffected. Above fc, it rolls off at −20 dB per decade for a single-pole stage.

The 2.2nF value places this capacitor solidly in the RF and high-frequency analog domain for typical resistor values. That’s why you’ll find it in:

• ADC anti-aliasing filters ahead of high-speed converters
• RF snubber networks to suppress switching transients
• Op-amp feedback networks for bandwidth limiting
• EMI/RFI suppression in power supply outputs
• I²C and SPI line filtering in noisy industrial environments

High-Pass Configuration

Swap the resistor and capacitor positions and you have a high-pass filter with the same cutoff frequency formula. A 2.2nF cap paired with a 7.23 kΩ resistor gives a 10 kHz high-pass — useful for AC coupling stages where you want to block DC and low-frequency noise but pass the signal band above 10 kHz.

PCB Layout Tips for 2.2nF Capacitors

When placing a capacitor on a PCB in this value range, layout discipline has a measurable impact on performance:

Keep placement close to the load. For decoupling duty, place the 2.2nF cap as close as physically possible to the VCC pin of the IC it’s serving. Trace inductance is the enemy — every millimetre adds parasitic inductance that raises the impedance at frequency.

Use a short, direct return path. The via to ground and the ground pour directly under the cap are as important as the cap placement itself. On a 4-layer board, dedicate an inner layer as a ground reference and stitch the cap’s GND pad to it with a via as close to the pad as your DRC allows.

Mind the solder mask clearance on 0402 and 0603 SMD. At this capacitance value and high frequency, parasitic inductance from long pads or tombstoning from asymmetric reflow can shift the effective resonant frequency enough to matter.

For filter circuits, match component placement to signal flow. Place the series resistor first (upstream), then the shunt capacitor to ground. This maintains a clean signal path and avoids routing loops that could couple noise.

Common 2.2nF Capacitor Part Numbers & Where to Find Them

Manufacturer	Part Number	Dielectric	Package	Voltage
Murata	GCM1885C1H222JA16D	C0G	0603	50V
TDK	C1608C0G1H222J080AA	C0G	0603	50V
Samsung	CL10C222JB8NNNC	C0G	0603	50V
Vishay	VJ0603D222JXPAJ	C0G	0603	200V
Kemet	C0603C222J5GACTU	C0G	0603	50V
Yageo	CC0603JRNPO9BN222	NP0	0603	50V

Useful Resources for Engineers

• Murata SimSurfing — Simulate frequency response and impedance curves for specific Murata MLCC part numbers
• DigiKey RC Filter Calculator — Calculate cutoff frequency for low-pass and high-pass RC filter stages
• Kemet SPICE Models — Download SPICE models for ceramic capacitors for simulation
• Capacitor Code Decoder (kiloohm.info) — Quickly decode any 3-digit capacitor marking
• IPC-2221 PCB Design Standard — The foundational PCB design standard covering component placement and spacing
• Murata “Capacitor Basics” Application Notes — In-depth technical notes on MLCC behaviour, DC bias effects, and dielectric selection

Frequently Asked Questions About the 2.2nF Capacitor

Q1: Is a 2.2nF capacitor the same as a 2200pF or 0.0022µF capacitor? Yes, exactly. All three notations describe the same capacitance value. Distributors and datasheets use different unit conventions depending on context, but 2.2 nF = 2200 pF = 0.0022 µF. The code 222 on the body always refers to this value regardless of which unit is shown in the catalog.

Q2: Can I substitute a 2.2nF capacitor with a 2.2nF film capacitor instead of ceramic? In many applications, yes. Film capacitors (polyester, polypropylene) offer excellent stability and low ESR, similar to C0G ceramic. The trade-off is physical size — a film cap at 2.2nF is considerably larger than an equivalent MLCC. In tight PCB layouts or high-frequency RF applications above a few megahertz, the ceramic MLCC is usually the better choice due to its lower parasitic inductance.

Q3: What resistor do I need to set a 10 kHz low-pass filter with a 2.2nF capacitor? Using fc = 1 / (2π × R × C), rearranged: R = 1 / (2π × fc × C) = 1 / (2π × 10,000 × 2.2×10⁻⁹) ≈ 7.23 kΩ. The nearest standard E24 value is 7.5 kΩ, which gives you a cutoff of approximately 9.65 kHz — close enough for most applications.

Q4: Why does my 2.2nF X7R capacitor behave differently at different temperatures? X7R dielectric has a capacitance variation of ±15% over −55°C to +125°C, plus additional drift under DC bias. If your circuit requires a stable, predictable time constant or filter corner, switch to a C0G/NP0 dielectric 2.2nF capacitor, which has negligible temperature and voltage dependence.

Q5: Is the 2.2nF capacitor polarised? No. Ceramic capacitors, including the 2.2nF 222-coded type, are non-polarised. You can install them in either orientation on the PCB without affecting performance. This contrasts with electrolytic and tantalum capacitors, which must be placed with correct polarity.

Final Thoughts

The 2.2nF capacitor might be one of the smallest line items on your BOM, but in RF, precision analog, and timing circuits it deserves the same level of specification discipline as any active device. Know your dielectric, understand how the RC time constant and cutoff frequency shift with your resistor values, and keep your PCB layout tight. Those three habits alone will save you more re-spins than almost any other single practice in analog and mixed-signal design.