KEMI Docs · Parts Practice
Reading Package Size Codes — 0603 and 1608 Are the Same Part (and Not)
Last updated: 2026-08-30
Chip resistors and capacitors are named by 4-digit size codes — and there are two overlapping systems. Imperial 0603 (1.6×0.8mm) and metric 0603 (0.6×0.3mm — imperial 0201) are completely different parts. A bare '0603' in a BOM is ambiguous, and real ordering accidents come from exactly this.
1
Length × width
Both systems put length in the first two digits and width in the last two. Imperial counts hundredths of an inch (0603 = 0.06×0.03in); metric counts tenths of a millimetre (1608 = 1.6×0.8mm). The trouble: numbers like 0402 and 0603 exist in both systems.
2
Conversion table
| Imperial | Metric | Size (mm) | Notes |
|---|---|---|---|
| 01005 | 0402 | 0.4 × 0.2 | metric 0402 ≠ imperial 0402 — top confusion zone |
| 0201 | 0603 | 0.6 × 0.3 | metric 0603 ≠ imperial 0603 |
| 0402 | 1005 | 1.0 × 0.5 | mainstream for compact production boards |
| 0603 | 1608 | 1.6 × 0.8 | the accepted hand-soldering floor |
| 0805 | 2012 | 2.0 × 1.25 | easy hand soldering; good for prototypes |
| 1206 | 3216 | 3.2 × 1.6 | when current/voltage margin is needed |
| 1210 | 3225 | 3.2 × 2.5 | common for high-capacitance MLCCs |
| 2512 | 6332 | 6.3 × 3.2 | power parts, current-sense resistors |
⚠ Always qualify 0402 and 0603
These two codes exist in both systems. Write '0603 (1608 metric)' everywhere, or standardise internal documents on metric codes. KEMI manages sizes by the metric 4-digit code internally.
3
Which size to pick
- Hand-soldered or repairable boards: 0603 (1608) or larger — 0805 (2012) if space allows.
- Dense production boards: 0402 (1005) balances cost, yield and density; 0201 and below only after talking to your assembler.
- Power positions: bigger code, bigger rating — 0603 resistors are typically 1/10W, 0805 1/8W, 1206 1/4W.
- MLCCs lose more effective capacitance to DC bias as they shrink — where capacitance matters, go one size up.
4
ICs use a different system
The 4-digit codes apply to two-terminal chips only. ICs use package name + pin count (SOT-23, SOIC-8, TQFP-64, QFN-32), and identical names can differ in pitch — always verify footprints against the datasheet's recommended land pattern.
FAQ
Why are imperial codes still used?
Distributor inventory systems are built on them, so imperial dominates purchasing; Japanese manufacturers embed metric codes in their part numbers. Both coexist — qualify your notation.
Which system does my CAD library use?
KiCad's standard library names both ('R_0603_1608Metric'); Eagle and Altium libraries usually use bare imperial codes — keep a mapping table if you manage sizes in metric.
Can 0201 be hand-soldered?
With a microscope and skill, barely — not practically. If a prototype includes 0201 or smaller, SMT assembly ends up cheaper.
See also
This article summarises the working rules KEMI uses in real design and fabrication work. For production, part datasheets and fab specifications take precedence.