Molex Connector Buying FAQ from an Admin Buyer: 5556, Power Supply, and Total Cost

I'm the office administrator for a 40-person engineering company. I handle component purchasing—roughly $350,000 annually, give or take a few thousand, across 12 vendors. I report to both operations and finance. When I took over purchasing in 2020, I didn't know a crimp terminal from a housing. I've learned by doing, and the lessons are not the ones in the datasheets.

We process 60-80 component orders a year. Not huge compared to a factory, but enough to see patterns. One pattern is that people search for “molex connector.” with a period. Another is that they ask “what's a Molex 5556?” as if that's a complete part number. This FAQ is for people in that situation, whether you're an admin buyer or an engineer who's doing procurement for the first time.

What is a Molex connector, really?

A “Molex connector” is a generic phrase for any connector made by Molex. In our drawings, it isn't enough. The series matters: Mini-Fit Jr., Micro-Fit, PicoBlade, CMC, and others all carry the Molex name but have different current ratings, pitch, locking features, and terminal systems.

The question everyone asks is “what's your price?” The better question is “what's the full part number?” That isn't just procurement talk. It's the difference between a smooth order and a $500 emergency.

What is a Molex 5556, and why can't I order it without a suffix?

The Molex 5556 is not a standalone connector. It's a family of female crimp terminals used in Mini-Fit Jr. power connectors. The number is a start, but the full part number includes wire gauge, plating, and packaging. A 5556 for 16-18 AWG is not the same as one for 20-22 AWG. The same physical shape can have tin or gold plating, and plating affects performance.

I learned this the hard way in our 2024 vendor consolidation project. We bought what looked like the right 5556 terminals from a new supplier. They didn't match the wire gauge in our harness. The line stopped for a day while we reordered. The delay was a cost that the quote didn't show.

When someone sends me a bill of materials with “Molex 5556,” I send it back. What I mean is: give me the full part from the approved vendor list, or at least the series, size, and plating. It takes two minutes to avoid a $500 mistake.

Why did my Molex connector quote seem expensive? The TCO lesson

Here's the moment I changed my mind. In March 2023, a new supplier quoted a very good price on 5556 terminals and Mini-Fit housings. The unit cost was 15% below our regular distributor. I placed the order. Then the invoice included freight, a small-order fee, and a payment term that made finance unhappy. And because I hadn't specified the plating clearly, the parts were the wrong type. We paid for a rush replacement from the regular distributor. That “cheap” order ended up costing more than the standard one would have.

Why does this matter? Because the unit price is just the visible part. Total cost of ownership includes the part, freight, handling, payment friction, receiving inspection, rework, downtime, and the risk of a field failure. I didn't fully understand that until a $3,000 order went sideways. The vendor didn't provide proper documentation, my expense report got rejected, and I ate part of the cost out of the department budget. Now I calculate TCO before comparing any vendor quotes.

Total cost includes the part, freight, handling, payment friction, receiving inspection, rework, downtime, and the risk of a field failure. The lowest unit price can still be the most expensive choice.

How do I order Molex connectors for a power supply?

For any power supply application, you need to look at the system, not just the connector. Start with the current rating. Then choose a series that can handle it: Mini-Fit Jr. is common for lower-voltage power interconnects, CMC handles more demanding high-current environments, and PicoBlade is for small signal wires. Then pick a housing with the right circuit count—2-pin, 4-pin, 14-pin, whatever the design calls for—and the correct terminals for the wire gauge.

The often-missed step is the crimp tool. A terminal that isn't crimped correctly can fail at the most inconvenient time. We have hand tools for repairs and a bench press for production harnesses. If you're buying connectors for a power supply and you skip the tooling, add it to the quote now.

To be fair, this feels like a lot for a non-engineer. But if you're the one placing the order, knowing the difference between a housing and a terminal will save you one embarrassing phone call.

What should I send when I ask for a Molex connector quote?

Now, when I get an engineering request, I use a short checklist: the full Molex part number, the quantity, the delivery date, and the packaging preference. If the engineer only gives me a series name like “Molex 5556” or “Mini-Fit Jr.,” I ask for the approved vendor part number. If they don't have it, I look for the housing, terminal, and crimp tool separately. That sounds obvious, but it's the step that prevents most of our rework.

I also ask for the manufacturer's lead time. A distributor can list “in stock” and still allocate stock differently for high-volume customers. We've had a quote for 50 pieces with a three-week lead time, and another quote for 500 pieces of the same part with a two-day lead time. Same part, different supply chain. The quote is not a menu. It's a promise.

Should I buy genuine Molex or compatible parts?

I have mixed feelings. Part of me wants to save budget. Another part knows that a connector that fails in the field is more expensive than the money saved. For low-voltage signal boards in an early prototype, a compatible part from a reputable source may work. For power supplies, medical products, or anything that ships to a customer, I buy genuine Molex. The reasoning is simple: the data sheet for a compatible part is not the same as a datasheet with full traceability and an approval chain.

Granted, compatible connectors can be perfectly fine. I've seen them work. But I've also seen a batch where the fit was fine until a temperature cycle, and then the retention force dropped. That experiment ended quickly. For our volume, the price difference between genuine and compatible is small next to the cost of a product failure. Choose with your eyes open.

What hidden costs should I look for in a Molex order?

As of January 2025, a quick look at Digi-Key, Mouser, and Newark listings shows 5556 terminals around $0.05-$0.35 each and Mini-Fit Jr. housings around $0.15-$0.80, depending on circuit count, plating, and quantity. But list prices are only half the story. Hidden costs usually come from:

• Freight minima and small-order handling fees
• Minimum order quantities that differ between distributors
• Customs or duties if the item ships from outside your region
• Obsolete part notices that force a redesign and a new purchase
• Packaging: a full reel is priced differently from cut tape or loose terminals

I'm not saying every “cheap” order is a trap. I'm saying that the cheapest quote is the easiest one to lose money on. The quote should include the exact supplier, the manufacturer's full part number, shipping terms, and the expected delivery date. If a vendor can't answer those, I use another vendor.

A note for people who searched “heartguide” or “how to unblock a number on phone”

This is not a traditional connector FAQ, but the search logs for our site include both terms. If you're here because of one of those searches, this page won't help with either. HeartGuide is a wearable blood pressure monitor made by Omron, not by Molex. And unblocking a number depends on your phone: on an iPhone, look in Settings > Phone > Blocked Contacts; on Android, the path is usually Settings > Calls > Blocked numbers.

I include it because the confusion is a good lesson for buyers. “Molex 5556” without a suffix is as incomplete as “HeartGuide” without checking the manufacturer. If a spec sheet doesn't identify the exact component, someone has to guess. Guessing creates the same kind of wrong orders as searching for a connector when you actually wanted a blood pressure monitor.