How to Read Ceramic Capacitor Codes

How to Read Ceramic Capacitor Codes

Ceramic disc capacitors are usually too small to print a full value like “470 picofarads” on the body, so manufacturers use a compact numeric code instead. Once you know how to decode it, you can identify any ceramic capacitor’s value in seconds — no datasheet required.

How to Read the Code

Most ceramic capacitors use a 2 or 3-digit code, always read in picofarads (pF) unless stated otherwise:

• 2-digit codes (e.g. 47, 22) are read directly as the value in pF — no multiplier involved.
• 3-digit codes follow the format XY-Z: the first two digits (X, Y) are the significant figures, and the third digit (Z) tells you how many zeros to add.

Example: Code 104 → 10 × 10⁴ pF = 100,000 pF = 100nF = 0.1μF (this is the most common capacitor value you’ll ever see, used constantly for decoupling).

Capacitor Code Reference Table

Common Uses by Value Range

• 1–100 pF: Oscillator and resonant circuits, RF tuning, timing crystals
• 100pF–10nF: Noise filtering, signal coupling, EMI suppression
• 0.1μF (104): The universal decoupling/bypass capacitor placed near IC power pins
• 1μF and above: Power supply filtering, bulk decoupling

Quick Tips

• A letter after the number (J, K, M) indicates tolerance — J = ±5%, K = ±10%, M = ±20%.
• All 3-digit codes are read in picofarads by default — there’s no separate code for nF or μF.
• Values under 10pF are sometimes marked with a decimal directly (e.g. “4R7” = 4.7pF) instead of the 3-digit system.
• When in doubt, use a multimeter with a capacitance mode or an LCR meter to confirm the actual value.

Reference chart and values shown are for standard ceramic disc capacitors following the common EIA 3-digit marking system.