Identify an Unknown Connector: Pitch, Markings, Series Match

How to Identify an Unknown Connector from Housing Markings and Pitch

Direct answer for buyers who already hold the sample

If you hold a connector with no part number, the fastest path to a sourcing line is to measure pitch center-to-center with calipers, count positions and rows, read the stamped or laser-etched code on the housing, and note polarization keys and lock style. Once those five numbers — pitch, positions, rows, code, mating style — are written down, a search against the 174,000-SKU catalog at icsourcedirect.com and the parametric filters at /products usually returns a probable series. We are an independent China connector distributor and procurement desk; when the part is ambiguous, we work from photos and your physical sample, then quote against the matched series, never a guess.

Why an identification workflow matters more than a guessing game

Russian and CIS maintenance, repair and operations (MRO) teams, contract electronics manufacturers, and small-batch integrators run into the same situation every week: a connector on a 2008 CNC controller, a 2014 laboratory analyzer, or a 2017 filling-line PLC has failed, the OEM has long since discontinued the part or has no local channel, and the only thing in front of you is the broken housing, a piece of attached wire, or a cell-phone photo. As Russian buyers usually phrase the question: «чем заменить разъём, если нет маркировки, только фото» — or in the shop-floor English variant: «how do I match a connector I cannot read». The temptation is to photograph the housing, post it on a forum, and pick whatever name comes back first. That shortcut burns time and stock. A 2.00 mm pitch JST PH and a 2.50 mm JST XH look almost identical at thumbnail size, but the crimp contacts, the retainer geometry, and the wire gauge range are not interchangeable, and a part-number-by-guess quote usually returns the wrong series and burns a lead-time week.

This is a method article — not a substitution guide and not a substitute-by-photo service. The goal is to give you a written procedure that takes an unmarked sample to a probable series, then to one or two candidate part numbers, on your own workbench. Once you have a probable series, you can submit a short list to the sourcing desk at icsourcedirect.com through the BOM-quoting flow at /baojia or the general inquiry form at /inquiry. We work from the candidate series, never from the visual guess, and we screen every line before quoting.

Tools you need at the bench

You can do most of the work with three items: a digital caliper readable to 0.01 mm, a 10× loupe or a phone-macro lens, and a strong desk lamp. Add a multimeter for sanity checks on continuity and a fine-tipped permanent marker for writing findings directly on the sample bag. A flatbed scanner at 600 dpi captures housing text better than a phone camera when the laser-etched code is faint. If you have access to a stereo microscope, use it for fine-pitch work — anything under 1.00 mm pitch is hard to read by eye.

Before you start, photograph the connector from four angles: top, mating face (the side that meets its counterpart), termination side (where the wires or PCB tails come out), and a profile shot that shows lock latches, mounting flanges, and any polarization key. Lay a ruler or a coin next to the sample in at least one frame; that becomes your scale reference if a remote reviewer needs to estimate dimensions you missed.

Step 1 — Measure pitch, pin count, and rows

The first three numbers you write down will narrow the search faster than anything else. Pitch is the center-to-center distance between two adjacent contacts. Measure across at least three adjacent contacts, divide by the count, and round to the nearest catalog value: 0.40 mm, 0.50 mm, 0.80 mm, 1.00 mm, 1.25 mm, 1.27 mm (0.050 inch), 1.50 mm, 2.00 mm, 2.50 mm, 2.54 mm (0.100 inch), 3.00 mm, 3.50 mm, 3.96 mm, 4.20 mm, 5.00 mm, 5.08 mm (0.200 inch), 6.20 mm, and so on. If you cannot fit caliper jaws between contacts, you are below 1.00 mm pitch; switch to the microscope and the microscope reticle, or stack five contacts and divide.

Count the total positions on the mating face, then count rows: one row (single inline), two rows (dual inline), or — for circular connectors — the number of pins around the insert. A 2.54 mm pitch, 10-position, single-row housing is a different family from a 2.54 mm pitch, 10-position, dual-row IDC header, and both are different from a 2.54 mm pitch, 10-pin D-sub. Without these three numbers you are searching blind; with them you can land on a series in seconds.

Write the pitch in millimeters, not inches, when you send the finding to a Chinese supplier — most catalog data on the icsourcedirect.com site uses metric pitch. If the part is genuinely inch-pitch, note both: a 1.27 mm pitch and a 0.050 inch pitch describe the same family of headers.

Step 2 — Read the housing code

Almost every housing carries some form of code. It may be molded into the plastic, laser-etched on the back, printed on a sticker, or stamped on a metal shield. Look for:

A short alphanumeric string (two to six characters). This is usually a series family code (XH, PH, SH, GH on JST; Mini-Fit, Micro-Fit, Nano-Fit, KK on Molex; DF13, DF40 on Hirose; CH, AMP-LATCH on TE Connectivity).
A longer manufacturer part number, sometimes with a date code, a lot code, and a country of origin. Two-digit year-week codes such as 2418 (year 2024, week 18) are common on Asian-made connectors and tell you the part is still being manufactured.
A safety mark — UL, CSA, VDE, TÜV, CE — which confirms the housing was made by a legitimate manufacturer and not a generic copy.
A material mark: PA66, PA9T, LCP, PBT, PPO. PA66 and PA9T are common in modern wire-to-board housings; PBT is older.

If you cannot see a code at all, the housing may be black-on-black laser etch under a matte finish. Raking light from the desk lamp at a low angle usually reveals it. A wipe with isopropyl alcohol removes release-agent haze that masks the etch.

The housing code alone will not always give you the full MPN. JST's "XH" is a series family, not a part number — the full MPN for a 4-position XH housing is XHP-4. A code such as "B4P-VH" on a JST-style VH housing tells you both series and position count in one stroke, but that format is not universal. Capture every character and let the catalog search do the resolution.

Step 3 — Capture style and polarization

Beyond pitch and code, four mechanical features identify the family almost as fast:

Mating style: crimp-on-wire, insulation-displacement (IDC), surface-mount (SMT), through-hole (THT), solder cup, or press-fit. The termination side of the housing tells the story; IDC housings show a sharp blade slot per contact, SMT housings show a flat pad with a metal solder tab, THT housings show square pins sticking through a board.
Lock style: friction lock, positive lock (a separate latch arm that snaps over the mating half), locking ramp (an integrated ramp on the housing that snaps into a window on the header), screw lock (D-subs, M12, M8), bayonet, twist-lock (M16, M23), or push-pull (LEMO-style).
Polarization: a single asymmetric keyway, a center key, multiple keys, or none at all. Headers with no key can be mated in either of two orientations; keyed headers can be mated in only one.
Mounting: board mount (through-hole or SMT), panel mount (with a square or hex flange), free-hanging (no mount), or in-line splice.

A 2.50 mm pitch, 4-position, single-row housing with friction lock and a center polarization rib on a 1.6 mm-thick PCB tail almost always belongs to the JST XH family or a JST XH-compatible family. A 2.54 mm pitch, 10-position, single-row housing with a friction lock and no polarization on a wire-side IDC blade is almost always a JST EH or a JST-compatible insulation-displacement series.

Step 4 — Check the wire and the PCB footprint

If wires are still crimped into the housing, the wire gauge and color can confirm the family. Japanese wire-to-board crimp families (JST XH/PH/SH/GH, Hirose DF13, Molex KK) typically use AWG 28 to AWG 22 stranded wire, 0.5 to 1.0 mm² cross-section. European terminal-block families (Phoenix Contact MSTB, WAGO 231/733, Weidmüller BL) take solid or ferruled conductors from 0.14 to 4 mm². RF and coax connectors show characteristic dielectric and shield dimensions that almost always map to a known series (SMA, SMB, MCX, MMCX, BNC, TNC, N-type, U.FL).

If the housing is still soldered to a PCB, the board side tells you which mating half to look for. Take a photo of the PCB pads under magnification; the land pattern — pin spacing, pad shape, and any polarization notch — is the footprint specification the manufacturer publishes. The mating half you need to source is the one that mates to that footprint.

Step 5 — Look up, then verify against the datasheet

Once you have pitch, positions, rows, code, and style, take the candidate series and search. The catalog at /products lets you filter by series family and by pitch; the brand pages at /manufacturers give you a brand-by-brand view; a category filter under /category/wire-to-board-connectors narrows to one family at a time. Look at the candidate MPNs, then open the manufacturer datasheet for at least one of them. The datasheet confirms dimensions, current rating, voltage rating, mating cycles, plating, and operating temperature — the parameters you must align before you order a part.

Two verification habits matter:

The mating face you measured is the male or female half of the connector. If your sample is the male half (pins sticking out), you source a female housing; if your sample is the female half (sockets), you source a male housing. Mixing those up is the single most common ordering error in the MRO segment.
The code on the housing is usually the housing-only code. The full connector line item often needs three or four parts: the housing, the crimp contacts (sold separately from the housing for most Japanese-style wire-to-board families), and the retention wedge or TPA (Terminal Position Assurance). A "Mini-Fit Jr. 4.20 mm 6-pin connector" is meaningless without knowing whether it is the panel-mount receptacle, the free-hanging plug, the through-hole header, the SMT header, or a wire-to-wire variant. Each has its own housing, contact, and retainer MPN. This is also why an RFQ that lists one MPN per BOM line, without separating housing, contact and retainer, almost always under-specifies the order.

How we work an identification request on the desk

When you send an unknown connector to icsourcedirect.com for sourcing, the workflow runs through five gates. We treat every step as a question we cannot skip, because quoting on a guess is what burns lead time.

Photo and dimensional intake. Send two or three photos with a ruler in frame, the pitch measurement, the position count, the row count, and the housing code. If you have a sample, ship it to the Shenzhen desk — the address is on /about.
Series candidate shortlist. Our desk maps your findings to two or three probable series. We list the family code, the brand, the candidate series, and what we still cannot confirm.
Datasheet pull and parameter check. We open the manufacturer datasheet for the top candidate and verify pitch, current rating, voltage rating, mating cycles, plating, and operating temperature.
RFQ line build. We build the RFQ line as housing + contact + retainer (where applicable), with packaging options per line. Packaging options — reel, cut tape, tube, tray, bulk — are confirmed on the quotation, since the same MPN in tray and in cut-tape can carry different price tiers and different lead-time behavior.
Quotation with screening note. We issue the quotation per line. If any line is still ambiguous after step 3, we mark it as "identification to be confirmed by sample" and decline to ship until the sample matches. We screen end users and end uses, classify before quoting, and decline transactions that cannot be screened. Delivery to Russia and the CIS is arranged under DDP where the quotation states it; transit times depend on lane and carrier availability and are not guaranteed.

When you should not identify from a photo at all

Some identification requests should not be answered from a photo. They include:

Critical systems with OEM-controlled qualification. When the connector sits in a circuit whose qualification, lot traceability, and regulatory paperwork are owned by the equipment OEM, identification from a photo is not a useful first step. The part may be visually generic; the qualification trail is not. Engage the OEM's authorized channel for those lines.
Patient-implanted and life-sustaining medical electronics. We do not write identification guidance for those applications. The qualification, regulatory paperwork, and lot traceability are not substitutable on visual grounds alone.
Defense, aerospace, and dual-use end uses. Requests carrying any of those contexts are out of scope for this method and out of scope for our desk. We do not identify or source connectors flagged for those end uses.
Samples with no visible code, no readable dimensions, and no attachment. If pitch cannot be measured (e.g., the contacts are corroded away), no code is visible under loupe or raking light, and no wire or PCB is attached, the identification has to fall back to the host equipment's BOM or the equipment manufacturer's spare-parts list. We will help you write that fallback request, but we will not quote on a guess.

These four cases are the boundary. If your request sits inside them, the right move is to pull the equipment's documentation, the OEM's spare-parts list, or the OEM's authorized channel — not the independent desk.

Common identification traps worth knowing

A few patterns come up often enough to call out as known traps.

JST XH vs JST PH. XH is 2.50 mm pitch, rated 3 A per circuit, typically with 4 to 16 positions. PH is 2.00 mm pitch, rated 2 A per circuit, typically with 2 to 16 positions. They look similar at a glance because both use a top-entry friction lock on a rectangular housing. If you measured 2.00 mm and wrote 2.50 mm, you will order the wrong family.
JST SH vs JST GH. SH is 1.00 mm pitch top-entry; GH is 1.25 mm pitch side-entry. A side-entry housing measured on the top can look like a top-entry housing if you do not check the cable exit angle.
Molex Mini-Fit Jr. vs Molex Micro-Fit 3.0. Mini-Fit Jr. is 4.20 mm pitch. Micro-Fit 3.0 is 3.00 mm pitch. Both use a positive lock. Both look like rectangular black housings with four to twenty-four circuits. A 0.5 mm error on the pitch call moves the buyer from one family to the other.
Hirose DF13 vs DF40. DF13 is a 1.25 mm pitch wire-to-board crimp family. DF40 is a 0.40 mm pitch board-to-board mezzanine family. They share a brand and a "DF" prefix; they do not share a mating interface. A photo taken from the wrong side of the board can read as either.
M12 vs M8 vs M16. All are sensor-style circular connectors with screw threads. The thread diameter is the giveaway: M8 is 8 mm thread, M12 is 12 mm, M16 is 16 mm. Coding (A, B, C, D, K, L, M, S, T, X) tells you the application (sensor, Profinet, Ethernet, power). A coding-error on the mating half can fry a sensor.
D-sub 9 vs D-sub 15 vs D-sub 25. The shell size (DE, DA, DB, DC, DD) gives the family. DE is the 9-pin shell; DA is the 15-pin shell; DB is the 25-pin shell. Counting pins from the mating face, not the solder cup side, avoids the most common reversal error.

If the sample sits on your bench and you have a caliper, none of these traps are hard to resolve. If you are working from a phone photo with no ruler, several of them are unresolvable — that is the single strongest argument for sending the sample.

What to send us when you want a desk identification

If you choose to submit the part to icsourcedirect.com for a desk identification, send us the following four items in one message through /baojia or /inquiry. We will respond with a probable series, an identification confidence level, and any clarification questions before issuing a quotation.

The five numbers. Pitch in millimeters, total positions, rows (1 or 2), housing code (or "no code visible"), and mating style (crimp, IDC, SMT, THT, solder, press-fit).
The four photos. Top, mating face, termination side, profile. Ruler or coin in one frame for scale.
The context. Host equipment name, model, year if known, the failure mode (mechanical, electrical, thermal), and the application (MRO, small-batch build, prototype, repair).
The desired quantity and packaging. Per-line quantity, packaging preference (reel, cut-tape, tube, tray, bulk), and any date-code or lot-code constraints (e.g., "date code must be 2024 or later").

If we cannot identify the part from photos plus the five numbers, we will tell you on the first response and ask for the sample. We do not quote on a guess, and we do not bill for the identification.

Boundaries of this service

We are an independent China connector distributor and procurement desk, not an authorized distributor for any of the brands we carry. The identification service is a pre-quoting step. Every match we propose is offered as "visually similar outline, mating interface matches on paper, electrically rated per datasheet" at the appropriate level of the substitution ladder — and you should verify against the original manufacturer datasheet and your own qualification process before adopting any cross-reference. Where a parameter is not documented in the manufacturer datasheet and not published in our catalog specifications, we mark it as unverified and ask for your engineering sign-off.

The identification workflow described above is intended for MRO, repair, equipment-refresh, and small-batch assembly contexts. It is not intended for OEM-controlled critical applications, for patient-implanted medical electronics, for defense or aerospace end uses, or for volume production runs that must carry a manufacturer-issued Certificate of Conformance. For those contexts, please engage the original manufacturer's authorized channel or the equipment OEM directly. We are happy to refer you back to those channels when that is the right answer.

Data Notes

By the ICSourcing supply-chain desk. Data through September 2026.

This article draws on the 174,000-SKU connector catalog at icsourcedirect.com, the manufacturer family pages at /manufacturers, and the parametric filters at /products, plus the publicly available series pages on JST (jst.com) and Molex (molex.com). Series pitch, current rating, and mating-style attributes in this article are written as commonly published on the manufacturer datasheets for the families named; specific values for any candidate line item must be verified against the manufacturer datasheet that is current at the time of quotation. The article does not enumerate stock levels or quote lead times by the line; both are confirmed on the quotation per line, per the workflow on /procurement and /baojia.

FAQ

What is the fastest way to identify an unknown connector from a photo?

The fastest path is to measure pitch center-to-center with a digital caliper, count positions and rows, read any stamped or laser-etched code on the housing, and note the lock style (friction, positive lock, latch arm, screw, bayonet, push-pull). With those numbers and a clear top-and-side photo with a ruler in frame, our desk can usually return two or three probable series within one working day. A photo alone, without measurements, leaves too much room for error: a 2.00 mm JST PH and a 2.50 mm JST XH look almost identical at thumbnail size, but they do not mate and they do not take the same crimp contacts.

Can you identify a connector from a sample we ship you?

Yes. Ship the sample to the Shenzhen desk at the address on /about, with a one-page note that lists pitch, position count, row count, host equipment, application context, and the desired quantity. A physical sample removes the photo-resolution ambiguity and lets us verify polarization, lock style, and plating under the microscope. We return the sample with the matching series, the full MPN for the housing, the contact, and the retainer (where applicable), and a per-line quotation.

How do I tell a JST XH from a JST PH if the housing code is unreadable?

Measure the pitch between two adjacent contacts. JST XH is 2.50 mm pitch and is typically rated 3 A per circuit; JST PH is 2.00 mm pitch and is typically rated 2 A per circuit. Both use a top-entry friction lock on a rectangular black housing. If the caliper reads 2.00 mm, it is PH; if it reads 2.50 mm, it is XH. Counting positions alone will not separate the two families because both span roughly 2 to 16 positions. The pitch reading is the single tiebreaker.

How do I tell a wire-to-board from a board-to-board connector on the bench?

A wire-to-board connector has wires or a wire-side crimp interface on one face and a PCB-tail header on the other. A board-to-board connector has PCB tails on both faces (a mezzanine or stacking connector) or PCB tails on one face and a mating socket on the other (a board-to-board plug-and-receptacle pair). If the sample has wires still attached, it is wire-to-board. If both faces show PCB pads or PCB pins and no wire is present, it is board-to-board, and you need to source the mating half as a separate line item.

How do I match the mating half when only the receptacle is in my hand?

Identify the receptacle family first (pitch, position count, row count, lock style, housing code). Then look up the mating plug or header in the same series. For wire-to-board families, the mating half is usually a through-hole or SMT PCB header with the same pitch and one additional row count. For board-to-board, the mating half is the corresponding plug or socket in the same series. Do not assume the part number of the receptacle tells you the part number of the header; the catalog usually lists them as separate line items.

Why do I need the housing, the contact, and the retainer as separate line items?

Most wire-to-board connector families — JST XH/PH/SH/GH, Molex Mini-Fit/Micro-Fit/KK, Hirose DF13 — sell the housing (the plastic body), the crimp contact (the metal terminal), and the retainer or TPA (the secondary lock) as three separate MPNs. A quote that lists one MPN per line, without separating these three, is incomplete. Quoting all three on the same line item lets you verify quantity per position, prevents a mismatch between housing pitch and contact series, and is the format our desk uses for the consolidated shipment.

What information should I send with an unknown-connector inquiry to speed up the quotation?

Send the five numbers (pitch, positions, rows, housing code, mating style), four photos (top, mating face, termination side, profile) with a ruler in one frame, the host equipment name and year, the failure mode, the application (MRO, small-batch build, prototype, repair), and the desired quantity and packaging per line. With those, our desk can usually return a probable series and a quotation on the first response. We screen end users and end uses, classify before quoting, and decline transactions that cannot be screened.