Metric Case Sizes in Germany: Why 0603 Names Two Different Walsin Parts

In Germany an engineer reading a metric case size sees 0603 as 0.6 × 0.3 mm. Walsin’s MLCC export uses 0603 to mean the imperial 1.6 × 0.8 mm part, and carries no metric case-size code on any of its 24,026 rows. In the chip resistor files Walsin Technology (Walsin) writes both codes, imperial first, so the literal string 0603 appears on 60,201 of 234,815 rows meaning two parts 7.1 times apart in board area.

---

Venatech Limited, an authorised Walsin distributor in Hong Kong, holds Walsin’s MLCC parametric export of 24,026 rows and all 137 chip resistor export files totalling 234,815 rows. This post measures how the Size column behaves in each and where the convention changes between them. Every part number below is real. Counts are of part numbers, not pieces.

Why does 0603 mean two different parts in Walsin’s data?

Because the two exports use different notations and one of them is unlabelled. The chip resistor files write imperial(metric) — 0603(1608) for the 1.6 × 0.8 mm part and 0201(0603) for the 0.6 × 0.3 mm part. The MLCC file writes the imperial code alone. So 0603 in the MLCC Size column is always the larger part, while 0603 inside the brackets of a resistor Size is always the smaller one.

Where the string 0603 appears	What it denotes	Nominal size	Rows	Match / mismatch vs a German metric reading
MLCC export, Size column	imperial 0603	1.60 × 0.80 mm	4,730	Mismatch — metric-first reading gives 0.6 × 0.3 mm
Chip resistor, 0603(1608)	imperial 0603	1.60 × 0.80 mm	42,374	Mismatch — same trap, but the metric code is shown
Chip resistor, 0201(0603)	metric 0603	0.60 × 0.30 mm	17,827	Match — this is the part a metric reading means

1.60 × 0.80 mm is 1.28 mm² of board. 0.60 × 0.30 mm is 0.18 mm². The ratio is 7.11 to 1. A footprint chosen on the wrong reading of the same four digits is not a near miss.

Does Walsin’s MLCC export give a metric case size at all?

No. We read the Size column on all 24,026 MLCC rows. It holds 16 distinct values — 0201, 0402, 0603, 0805, 1206, 1210, 1808, 1812, 1825, 2211, 2220, 2225, 0306, 0505, 1111 and 01R5 — plus one defective row where the series name and a tab character have been jammed into the field. Every one of the 16 is an imperial code or a Walsin size name. Not one row carries a metric designation.

The columns immediately to the right are metric. L, W and T are millimetres. So on a single MLCC row an imperial-only case code sits beside three metric dimensions, with nothing in the file stating which system the case code belongs to.

Column	Convention	Example value on MT18B103K100
Size	imperial code, unlabelled	0603
L	millimetres	1.60±0.10
W	millimetres	0.80±0.10
T	millimetres	0.80±0.07

The dimensions are the reliable field. If a selection is built on L and W rather than on Size, the notation question disappears. That is also the practical check on any incoming Walsin BOM: read the millimetres, not the four digits.

How many rows does the 0603 collision actually touch?

60,201 of the 234,815 chip resistor rows, and 4,730 of the 24,026 MLCC rows. The 0402 code collides the same way, because metric 0402 is imperial 01005.

Four digits	Imperial meaning	Rows reading it as imperial	Metric meaning	Rows reading it as metric	Total rows affected
0603	1.60 × 0.80 mm	42,374 chip resistor + 4,730 MLCC	0.60 × 0.30 mm	17,827 chip resistor	64,931
0402	1.00 × 0.50 mm	28,085 chip resistor + 3,991 MLCC	0.40 × 0.20 mm	755 chip resistor	32,831

No other code in either file collides. 1608, 2012, 3216, 1005, 6432, 5025, 3225, 3248, 1632, 3264, 2550, 0816 and 2037 all appear only as metric codes, and 0805, 1206, 1210, 2010, 2512, 1218, 0612, 1225, 1020 and 01005 only as imperial ones. The ambiguity is confined to exactly two codes, and both of them are high-volume.

Inside the automotive subsets that a German tier-1 BOM is most likely to contain, the split is: 18,567 automotive chip resistor rows at 0603(1608) against 6,783 at 0201(0603), and 883 automotive MLCC rows reading 0603 against 240 reading 0201. The nine Size values across the 102,995 automotive chip resistor rows all carry both codes; the nine across the 3,082 automotive MLCC rows carry none.

What does the same specification look like at both sizes?

Here is one 10 nF X7R 10 Vdc MT-series line and one 10 kΩ ±1% automotive general purpose resistor line, each at both case sizes, with the dimensions that settle the question.

Part number	Size as exported	Actual L × W	Metric case code	Match / mismatch vs a 1608 footprint
MT18B103K100	0603	1.60 × 0.80 mm	1608	Match — this is the 1608 part
MT03B103K100	0201	0.60 × 0.30 mm	0603	Mismatch — 7.1× smaller, same 10 nF
MG18B103K100	0603	1.60 × 0.80 mm	1608	Match — but MG carries no AEC-Q200 claim
MG03B103K100	0201	0.60 × 0.30 mm	0603	Mismatch — 0201 and not qualified
MR06X1002FTL	0603(1608)	1.60 × 0.80 mm	1608	Match — 10 kΩ, 1/8 W
MR02X1002FAL	0201(0603)	0.60 × 0.30 mm	0603	Mismatch — same 10 kΩ at 1/20 W

The two MLCC pairs hold the identical capacitance, dielectric, tolerance and rated voltage at both sizes. Nothing in the specification fields distinguishes them. The resistor pair holds the same resistance and tolerance and differs in rated power by a factor of 2.5 — 1/8 W against 1/20 W — which is the real consequence of getting the size wrong on a resistor rather than a capacitor.

Is there a third notation inside the part number?

Yes, and it is neither imperial nor metric. Walsin encodes case size in characters three and four of the MLCC part number using its own two-digit scheme. Across the 3,082 automotive MLCC rows the mapping is one-to-one with the Size column and has no collisions:

Code in part number	Size column	Metric	Automotive rows
03	0201	0603	240
15	0402	1005	685
18	0603	1608	883
21	0805	2012	736
31	1206	3216	406
32	1210	3225	118
43	1812	4532	7
46	1825	4564	2
55	2220	5750	5

So an engineer in Germany working from a Walsin MLCC part number has to hold three systems at once: 18 in the part number, 0603 in the Size column, and 1608 in the metric convention the drawing is dimensioned in. The chip resistor part number uses a different two-digit set again — 06 for 0603(1608) and 02 for 0201(0603), as MR06X1002FTL and MR02X1002FAL show. For the rest of the part number structure, see How to read a Walsin MLCC part number, and for the general case-size question, Passive component case sizes, imperial and metric.

Where does Walsin write one imperial size two different metric ways?

At 1225. 1,708 chip resistor rows read 1225(3264) and 47 read 1225(3263) — the same imperial case size with two metric spellings one digit apart. The 47 are the Metal Foil Low Ohm Power Sensing series, where WW25YR001FTL is a 1 mΩ, ±1%, 2 W part. The 1,708 are the Thick Film Wide Terminal Power series.

Size string	Series it appears in	Rows	Match / mismatch
1225(3264)	Thick Film Wide Terminal Power	1,660	Reference spelling
1225(3264)	Thick Film Wide Terminal Power Low Ohm	48	Match
1225(3263)	Metal Foil Low Ohm Power Sensing	47	Mismatch — 3263 against 3264

Imperial 1225 is 3.2 × 6.4 mm, so 3264 is the arithmetically correct metric code and 3263 is not. A grouping query on the Size string returns 1225 as two case sizes, and a part-count by size under-reports the wide-terminal family by 47 rows.

What should a German engineer do with a mixed Walsin BOM?

Three things, in order. Read the millimetre dimensions rather than the case code wherever the export gives them. Treat 0603 and 0402 as ambiguous on any line that arrived without its metric code. And group by the two-digit code inside the part number when counting, because that field is unambiguous within each product line.

What Venatech adds over a manufacturer search page is that the normalisation has already been done across both exports, so a BOM comes back with imperial code, metric code and millimetre dimensions on every line, and the lines where the four digits were ambiguous are named rather than silently resolved. We will not tell you a part is equivalent. We will show you where it differs, field by field. The full range is on the Walsin chip resistor range page.

The short version

Walsin’s MLCC export carries no metric case-size code on any of 24,026 rows, while all 234,815 chip resistor rows carry both codes with imperial first. 0603 and 0402 are the only two codes that collide, and they touch 64,931 and 32,831 rows respectively. The imperial 0603 part is 7.11 times the board area of the metric 0603 part. 1225 is written two metric ways, 3264 on 1,708 rows and 3263 on 47.

Send the BOM in whatever notation it already uses and we will return every line with the imperial code, the metric code and the millimetre dimensions side by side, and flag the lines where the four digits could have meant either part.

Faster than an email. The cross-reference tool takes a pasted list or a spreadsheet and returns Walsin candidates field by field, differences named. Ready stock is a dated snapshot of what is physically in Hong Kong, so a footprint decision and an availability decision happen together.

---

Frequently asked questions

<!– wp:rank-math/faq-block {"questions":[{"id":"faq-question-01","title":"Is 0603 imperial or metric in Walsin's data?","content":"It depends on the file. In the MLCC export, where 4,730 rows read 0603, it is always imperial 1.6 × 0.8 mm and no metric code is given anywhere. In the chip resistor files it is imperial when it appears before the bracket, as 0603(1608), and metric when it appears inside, as 0201(0603).”,”visible”:true},{“id”:”faq-question-02″,”title”:”Does Walsin publish metric case sizes for its MLCC range?”,”content”:”Not in the parametric export. All 24,026 rows carry an imperial or Walsin-specific code in the Size column and none carries a metric designation. The L, W and T columns are in millimetres on 2,989 of the 3,082 automotive rows, so the dimensions are the dependable field rather than the case code.”,”visible”:true},{“id”:”faq-question-03″,”title”:”How many Walsin part numbers are affected by the 0603 ambiguity?”,”content”:”64,931 rows in total: 42,374 chip resistor rows and 4,730 MLCC rows where 0603 is the imperial code, and 17,827 chip resistor rows where it is the metric code of imperial 0201. The 0402 code collides the same way on 32,831 rows, because metric 0402 is imperial 01005.”,”visible”:true},{“id”:”faq-question-04″,”title”:”What is the size code inside a Walsin MLCC part number?”,”content”:”Characters three and four. Across the 3,082 automotive MLCC rows the mapping is one-to-one and collision-free: 03 is 0201, 15 is 0402, 18 is 0603, 21 is 0805, 31 is 1206, 32 is 1210, 43 is 1812, 46 is 1825 and 55 is 2220. Chip resistors use a different two-digit set.”,”visible”:true},{“id”:”faq-question-05″,”title”:”How much bigger is an imperial 0603 part than a metric 0603 part?”,”content”:”7.11 times in board area. Imperial 0603 is 1.60 × 0.80 mm, which is 1.28 square millimetres. Metric 0603 is imperial 0201 at 0.60 × 0.30 mm, which is 0.18 square millimetres. MT18B103K100 and MT03B103K100 are both 10 nF X7R 10 Vdc parts at those two sizes.”,”visible”:true},{“id”:”faq-question-06″,”title”:”Why does Walsin’s data show 1225 as two different metric sizes?”,”content”:”Because 1,708 rows read 1225(3264) and 47 read 1225(3263). Imperial 1225 is 3.2 × 6.4 mm, so 3264 is correct and 3263 is not. The 47 affected part numbers are all in the Metal Foil Low Ohm Power Sensing series. Venatech has flagged it for written confirmation from Walsin.”,”visible”:true},{“id”:”faq-question-07″,”title”:”Does Venatech hold stock in Germany?”,”content”:”No. Venatech Limited is in Hong Kong, with group entities in Shenzhen, Singapore and Jiangmen and Chengdu in preparation. There is no German entity and no European inventory. Everything ships from Hong Kong, and ready stock is always a dated snapshot rather than a live feed.”,”visible”:true}],”listStyle”:””,”titleWrapper”:”h3″,”titleCssClasses”:””,”contentCssClasses”:””,”sizeSlug”:””} –>

---

---

Three ways to get this answered today

1. Cross a part, free. Paste up to 500 part numbers, or drop an Excel or CSV file, into the free cross-reference tool. It is matched against Walsin’s published catalogue and returns candidates field by field, with every difference from your original stated rather than hidden. Filter by commercial or automotive grade, or for soft termination, high temperature, safety certified, high Q / low ESR or low profile. There is no login and no charge.

2. Send the whole BOM. Upload a BOM and request a quote and we will come back line by line — including the lines we cannot help with, which is usually the more useful half of the answer.

3. Check the shelf before you commit. Ready stock shows what was physically in Hong Kong as at 23 September 2026. It is a dated snapshot, never a live feed, and quantities are never permanent.

Why take our word for any of this? Don’t — check it.

Venatech Limited (威納電子有限公司) is an authorised Walsin Technology distributor in Hong Kong. Confirm that with Walsin rather than with us. On the safety capacitor series we hold UL file E182369, which is searchable in UL’s own public database, together with TUV certificates R50381780 and R50195920 and CQC CQC20001280137 and CQC20001280136, against EN 60384-14:2023, IEC 60384-14:2023 and UL 60384-14. We hold 28 Walsin datasheets, 451 pages, and we will send the one covering your part number. Shipments arrive in original sealed Walsin packaging with lot and date-code traceability, and a certificate of conformity is available per shipment on request.

We will also tell you what we do not hold, which no competitor publishes. REACH, SVHC, conflict minerals, PFAS, China RoHS, ISO 9001, IATF 16949, PPAP, IMDS and a Declaration of Conformity appear nowhere in those 451 pages. You would rather hear that from us now than from your own supplier-approval team later. AEC-Q200 is compliant in Walsin’s own words and never certified, we hold no manufacturer’s end-of-life or allocation list for any brand, and qualification in your own circuit stays with you. We will not tell you a part is equivalent. We will show you where it differs.

Venatech Limited · Unit 207, 2/F, Sun Ling Plaza, 30 On Kui Street, Fanling, N.T., Hong Kong · (852) 2628 4777 · Hong Kong, Shenzhen, Singapore and Jiangmen, with Chengdu in preparation.