SMD resistor and capacitor sizes: 0402, 0603, 0805 and 1206 explained

Most resistors and ceramic capacitors on a modern PCB are chip parts with a four-digit size code. The code tells you the length and width of the part. It does not tell you the value, the tolerance or the voltage, so a BOM line needs all of them. This guide explains the codes we see most often in orders from India and what to check before you send a list.

You can see the chip resistors and capacitors we keep in passive components. For a full board, send the list through upload a BOM and we quote every line in INR with one GST invoice.

What the four digits mean

The common codes are imperial: the first two digits are the length and the last two the width, in hundredths of an inch.

Be careful with the metric names. A metric "0603" is the imperial 0201, which is much smaller. If a datasheet or a supplier list uses metric codes, write "imperial" or "metric" next to the size on your BOM.

The size must match the pads

The size code has to match the copper pads on your PCB. A 0603 part on 0402 pads will not sit flat, and a 0402 part on 0805 pads can tombstone (stand up on one end) during reflow. Changing the size is a layout change, not a purchasing change.

Power and voltage grow with size

A bigger chip can spread more heat and usually has a higher working voltage. As a rough guide, chip resistors are often rated about 1/16 W for 0402, 1/10 W for 0603, 1/8 W for 0805 and 1/4 W for 1206, but the datasheet of the actual part decides. For a current-sense resistor or a resistor on mains-derived voltage, choose the size from the power and voltage, not from what is already on the reel.

Ceramic capacitors lose capacitance under DC voltage, and small sizes lose more. A 10 µF capacitor in 0402 at its rated voltage can behave like a much smaller capacitor. If the value matters, pick a larger size or a higher voltage rating.

Hand soldering or machine assembly

For hand soldering and repair, 0805 and 1206 are the easiest. 0603 is fine with a fine tip and some practice. 0402 is meant for machine assembly. If your prototype is soldered by hand and production is machine assembled, design for the production size and accept slower prototype work.

What to write on the BOM

For a resistor: value, tolerance (for example 1 % or 5 %), size code, power rating if it matters, and the manufacturer part number if you have one. For a ceramic capacitor: value, voltage, dielectric (C0G / NP0, X7R, X5R), tolerance and size code. "10k 0603" is enough for many pull-up resistors, but "10 µF" alone is not enough for a capacitor.

If you are not sure, keep the original manufacturer part number on the line and say that an equivalent is allowed. See also BOM best practices.

Common questions

Is 0603 the same in every catalogue?

No. Imperial 0603 is 1.6 × 0.8 mm, while metric 0603 is 0.6 × 0.3 mm (imperial 0201). Always say which system you use.

Can I replace a 0603 resistor with 0805 on the same board?

Only if the pads were designed for it. On 0603 pads an 0805 part will not solder properly.

Which size should a beginner use?

0805 or 1206 for boards soldered by hand; they are big enough to hold with tweezers and see the marking.

Do you sell small quantities of chip resistors?

Yes. Prototype quantities on cut tape are fine, and reels can be quoted for assembly runs.