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MLCC Dielectric Class and Temperature Code Reference

A ceramic capacitor line on a BOM often carries a dielectric code like X7R or C0G, and the code decides whether a substitute is safe. This reference decodes each code into its temperature range and allowed capacitance drift, and shows how the three characters are built.

Download:
CodeClassOperating rangeCapacitance change over rangeMeaning for sourcing
C0G
Class I
-55 to +125 deg C
0 +/-30 ppm/deg C
Very stable, low loss; used for timing, filters and RF. Often listed as NP0.
U2J
Class I
-55 to +125 deg C
-750 +/-120 ppm/deg C
Intentional negative temperature coefficient used to compensate other parts.
X7R
Class II
-55 to +125 deg C
+/-15 %
General purpose decoupling and bypass; capacitance falls with DC bias.
X7S
Class II
-55 to +125 deg C
+/-22 %
Looser than X7R, higher volumetric efficiency.
X7T
Class II
-55 to +125 deg C
+22 / -33 %
Wider drift for higher capacitance in small bodies.
X8R
Class II
-55 to +150 deg C
+/-15 %
Automotive under hood and high temperature designs.
X6S
Class II
-55 to +105 deg C
+/-22 %
Common for dense mobile decoupling where 105 deg C is enough.
X5R
Class II
-55 to +85 deg C
+/-15 %
Consumer and indoor equipment; not a drop in for 125 deg C designs.
Y5V
Class II
-30 to +85 deg C
+22 / -82 %
Large capacitance swing; avoid where value matters.
Z5U
Class II
+10 to +85 deg C
+22 / -56 %
Narrow range, low cost bulk decoupling in older designs.
Letter 1: X
Decoder
Low limit -55 deg C
n/a
First letter sets the lowest operating temperature.
Letter 1: Y
Decoder
Low limit -30 deg C
n/a
First letter sets the lowest operating temperature.
Letter 1: Z
Decoder
Low limit +10 deg C
n/a
First letter sets the lowest operating temperature.
Digit 2: 5
Decoder
High limit +85 deg C
n/a
Second character sets the highest operating temperature.
Digit 2: 6
Decoder
High limit +105 deg C
n/a
Second character sets the highest operating temperature.
Digit 2: 7
Decoder
High limit +125 deg C
n/a
Second character sets the highest operating temperature.
Digit 2: 8
Decoder
High limit +150 deg C
n/a
Second character sets the highest operating temperature.
Letter 3: R
Decoder
n/a
+/-15 %
Third letter sets the allowed capacitance change.
Letter 3: S
Decoder
n/a
+/-22 %
Third letter sets the allowed capacitance change.
Letter 3: T
Decoder
n/a
+22 / -33 %
Third letter sets the allowed capacitance change.
Letter 3: V
Decoder
n/a
+22 / -82 %
Third letter sets the allowed capacitance change.

Class II and III values are measured without DC bias. In use, applied voltage reduces effective capacitance, sometimes by half or more on small high-value parts, so size the part from the manufacturer's DC bias curve. Dielectric substitution should always go through engineering approval.

Alternate part approval review

Optional: we look at how alternates are recorded in your ERP and suggest a structure that keeps dielectric and rating data searchable.

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How to use the reference

Search the code from your BOM or from a distributor listing. The top block lists the codes you will meet most often, and the bottom block shows how to decode any three character code yourself. Use it before accepting an alternate: an engineer can tell at a glance whether an X5R is being offered for an X7R requirement.

  • Search a code such as X7R or the letter you want decoded
  • Compare operating range before capacitance change
  • Export the table to attach to an alternate approval record

How the EIA code is read

Class II and III capacitors use three characters. The first letter is the low temperature limit, the digit is the high temperature limit, and the last letter is the maximum capacitance change over that range. So X7R means -55 to +125 deg C with no more than +/-15 percent change. Class I parts such as C0G use a different scheme that states a temperature coefficient in parts per million per degree, which is why they are far more stable.

What it means when approving an alternate

A part with a wider operating range and equal or tighter capacitance change can usually replace a lesser one, so X7R can often stand in for X5R but not the reverse. C0G cannot be replaced by a Class II part in a filter or timing circuit, because the capacitance will shift with temperature and bias. Voltage rating, case size, and DC bias behaviour also matter, so treat the code as one filter, not the full answer.

Common mistakes

Buyers sometimes treat Y5V as a cheaper X7R. It is not: its capacitance can fall by more than 80 percent at temperature extremes. Another error is ignoring DC bias, which can make a 10 uF part in a small body deliver only a few microfarads at the working voltage. Record dielectric, voltage and size together in your ERP item description so searches return true equivalents.

Frequently Asked Questions

Is NP0 the same as C0G?

In practice yes. NP0 is the older name for the Class I dielectric that EIA calls C0G, with a temperature coefficient near zero. Manufacturers use both labels for the same behaviour.

Can I replace X5R with X7R?

Often yes, because X7R covers a wider temperature range with the same +/-15 percent change. Confirm voltage rating, case size, DC bias curve and height, and get engineering sign off.

Why does my 10 uF capacitor measure much lower in circuit?

Class II ceramics lose effective capacitance as DC voltage rises. Small bodies and high capacitance values lose the most, so the datasheet bias curve shows what you really get at the rail voltage.

Should I use Y5V in new designs?

It is rarely a good idea. Its capacitance swing is very large, and most designers choose X5R, X6S or X7R when the value must hold. Check with the design engineer before accepting it as an alternate.

If alternate capacitor approvals live in email threads, we can build a private agent over your ERP and engineering documents that checks dielectric and rating before an alternate is proposed.

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