How to Identify Molex Connectors: Series, Pitch & Application Guide
Molex connectors are everywhere — in your PC power supply, automotive wiring harness, industrial control panel, and hobby electronics. But with dozens of Molex series on the market, identifying the exact connector you're working with can be genuinely confusing.
This guide gives you a systematic method to identify any Molex connector by pitch, housing features, locking mechanism, and application context — so you can find the right replacement or mating connector the first time. Shop all Molex connectors at Keszoox.
Why Molex Connector Identification Matters
Unlike JST connectors (which are keyed and series-specific), many Molex connectors look visually similar but are not interchangeable. Forcing a mismatched Molex connector can damage the housing, bend pins, or — in power applications — create a fire hazard by exceeding the connector's current rating.
Correct identification ensures: proper mating and locking, correct current and voltage ratings, mechanical compatibility with your PCB footprint, and availability of replacement parts.
Step 1: Measure the Pitch
Pitch — the center-to-center distance between adjacent pins — is the single most important measurement for connector identification. Use a digital caliper for accuracy.
How to measure: Place the caliper tips on the center of two adjacent pins (or the center of two adjacent cavities in the housing). The reading is your pitch.
| Pitch | Molex Series | Common Application |
|---|---|---|
| 1.0 mm | Molex Pico-EZmate | Ultra-compact consumer electronics |
| 1.25 mm | Molex PicoBlade | Compact electronics, similar pitch to JST GH |
| 2.0 mm | Molex Micro-Latch | Consumer electronics, wire-to-board |
| 2.54 mm | Molex KK 254 / SL | PCB headers, prototyping, legacy systems |
| 3.0 mm | Molex Micro-Fit 3.0 | Power electronics, PC internals, servers |
| 4.2 mm | Molex Mini-Fit Jr. | PC ATX power, high-current industrial |
| 6.35 mm | Molex Standard / Nylon | Automotive, heavy industrial |
Pro tip: If you don't have a caliper, count the pins and measure the total housing width. Divide by (pin count − 1) to estimate pitch. This won't be as accurate but narrows down the options significantly.
Step 2: Count the Pins and Note the Row Configuration
- Single-row: Most common in signal connectors (KK 254, PicoBlade, Micro-Latch)
- Dual-row: Common in power connectors (Micro-Fit 3.0, Mini-Fit Jr.) and high-density signal connectors
- Dual-row with staggered pins: Characteristic of Micro-Fit 3.0 — pins are offset between rows for better contact retention
The combination of pitch + row count + pin count uniquely identifies most Molex connectors.
Step 3: Examine the Locking Mechanism
Friction Lock (No Latch): The connector relies on friction to stay connected. Common in Molex KK 254 and older SL series. Identifying feature: smooth housing sides, no visible latch or tab.
Side Latch (Single Latch): A latch on one side that clicks over a tab on the header. Common in Molex Micro-Latch (2.0mm) and some PicoBlade variants. Identifying feature: a small tab or wing on one side of the housing.
Dual Side Latch: Latches on both sides. Common in Molex Micro-Fit 3.0. Identifying feature: symmetrical tabs on both sides — squeeze both simultaneously to release.
Panel Latch / Positive Lock: A large, prominent latch for high-vibration environments. Common in Molex Mini-Fit Jr. (4.2mm). Identifying feature: a large, clearly visible latch requiring deliberate force to release.
Step 4: Check the Housing Color and Material
- Natural (off-white / cream): Classic Molex KK 254 and SL series
- Black: Micro-Fit 3.0, Mini-Fit Jr., and most modern Molex series
- White: PicoBlade and some Micro-Latch variants
- Colored (red, blue, yellow): Polarity identification or specific automotive applications
Important: Always confirm with pitch and locking mechanism — never rely on color alone.
The 5 Most Common Molex Series: Identification Guide
1. Molex KK 254 — 2.54mm Pitch
Pitch: 2.54mm | Rows: Single | Current: 3A per contact | Lock: Friction
How to identify: 2.54mm pitch (matches standard 0.1" grid), natural (cream/white) or black housing, no locking latch — friction fit only, single row 2–16 pins, rectangular housing with square pin cavities.
Common applications: PCB power connectors, fan headers, legacy computer peripherals, industrial control panels.
➡️ Shop Molex KK 254 2.54mm Connectors
2. Molex PicoBlade — 1.25mm Pitch
Pitch: 1.25mm | Rows: Single | Current: 1A per contact | Lock: Side latch
How to identify: 1.25mm pitch (very fine, requires magnification), white or natural housing, small side latch on one end, single row 2–15 pins. Often confused with JST GH (also 1.25mm) — check the latch style and terminal design. Not interchangeable with JST GH despite same pitch.
Common applications: Portable electronics, compact sensor modules, battery connections in small devices, FPV drones.
➡️ Shop Molex PicoBlade 1.25mm Connectors | PicoBlade Complete Guide
3. Molex Micro-Latch — 2.0mm Pitch
Pitch: 2.0mm | Rows: Single | Current: 2A per contact | Lock: Side latch
How to identify: 2.0mm pitch, white or black housing, visible side latch on one end, single row 2–15 pins, slimmer profile than KK 254.
Common applications: Consumer electronics, wire-to-board connections in compact devices.
➡️ Shop Molex Micro-Latch 2.0mm Connectors
4. Molex Micro-Fit 3.0 — 3.0mm Pitch
Pitch: 3.0mm | Rows: Single or Dual | Current: 5A per contact | Lock: Dual side latch
How to identify: 3.0mm pitch, black housing (standard), dual side latches — squeeze both sides to release, single or dual row 2–24 circuits, staggered dual-row pin arrangement (pins offset between rows), larger and more robust than Micro-Latch.
Common applications: PC power supplies (internal connectors), industrial power distribution, server hardware, high-current LED drivers.
➡️ Shop Molex Micro-Fit 3.0mm Connectors | Micro-Fit 3.0 Complete Guide
5. Molex Mini-Fit Jr. — 4.2mm Pitch
Pitch: 4.2mm | Rows: Dual | Current: 13A per contact | Lock: Panel latch (positive lock)
How to identify: 4.2mm pitch — noticeably larger than Micro-Fit, black or natural housing, large prominent panel latch requiring deliberate force to release, always dual-row, rectangular terminals with distinctive shape. The largest commonly encountered Molex series in consumer electronics.
Common applications: PC ATX power connectors (24-pin, 4-pin, 8-pin), industrial power distribution, automotive power systems.
➡️ Shop Molex Mini-Fit Jr. 4.2mm Connectors | Mini-Fit Jr. Complete Guide
Molex vs JST: How to Tell Them Apart
| Feature | Molex | JST |
|---|---|---|
| Terminal design | Larger, more robust crimp barrel | Smaller, finer crimp wings |
| Housing material | Nylon (PA66), often stiffer | Nylon (PA66), often more flexible |
| Locking style | Varies by series (friction to panel latch) | Mostly friction or side latch |
| Current rating | Generally higher (up to 13A) | Generally lower (1–3A typical) |
| Common use | Power electronics, industrial, automotive | Signal, low-power, hobby electronics |
| Interchangeable? | No — even at the same pitch, Molex and JST connectors are NOT interchangeable | |
Quick Identification Checklist
- Measure the pitch with a caliper — narrows it to 1–2 series immediately
- Count the pins and note single vs dual row
- Examine the locking mechanism — friction, side latch, dual latch, or panel latch?
- Note the housing color — cream/white suggests KK 254 or older series; black suggests modern series
- Check the application context — power supply? Signal? Automotive? This confirms the series
Frequently Asked Questions
How do I tell Molex KK 254 from a generic 2.54mm header? Molex KK 254 uses a Molex-specific crimp terminal and housing geometry. Generic 2.54mm headers (DuPont-style) use a different terminal design. They are not interchangeable despite having the same pitch.
Is Molex Micro-Fit 3.0 the same as Mini-Fit Jr.? No. Micro-Fit 3.0 has a 3.0mm pitch and 5A per contact rating. Mini-Fit Jr. has a 4.2mm pitch and 13A per contact rating. Both are black dual-latch connectors but significantly different in size.
Can I use a Molex PicoBlade instead of a JST GH connector? No — despite both having 1.25mm pitch, PicoBlade and JST GH use different terminal designs and housing geometries. They will not mate with each other's headers.
How do I find the Molex part number for an unknown connector? Measure the pitch, count the pins, note the row configuration and locking style, then use Molex's online parametric search at molex.com. The housing often has a small part number molded into it — check with a magnifying glass.
What's the current rating of Molex KK 254? Molex KK 254 is rated at 3A per contact at 250V AC/DC. For power applications requiring more than 3A, use Molex Micro-Fit 3.0 (5A) or Mini-Fit Jr. (13A).
What is the difference between Molex Micro-Fit 3.0 and Mini-Fit Jr.? Micro-Fit 3.0 is 3.0mm pitch, 5A per contact, for compact power distribution. Mini-Fit Jr. is 4.2mm pitch, 13A per contact, for high-current applications like ATX power supplies. Not interchangeable.
Shop Molex Connectors at Keszoox
Keszoox stocks the complete range of Molex connector series — housings, crimp terminals, and PCB headers — ready to ship worldwide.
- Molex PicoBlade 1.25mm Connectors
- Molex Micro-Latch 2.0mm Connectors
- Molex KK 254 2.54mm Connectors
- Molex Micro-Fit 3.0mm Connectors
- Molex Mini-Fit Jr. 4.2mm Connectors
- All Molex Connectors
Related guides: Molex Connector Types Guide | Molex Micro-Fit 3.0 Complete Guide | Molex Mini-Fit Jr. Complete Guide | How to Measure Connector Pitch