I remember staring at a pile of screws after a botched IKEA assembly. Two bags, almost identical, but one said ’10 x 24′ and the other ‘5 x 80’. My brain just short-circuited. Are 10 x 24 and 5 x 80 machine screws the same? The answer, as I learned the hard way, is a resounding no. It’s not just a different way of saying the same thing; it’s a whole different language of measurement.
You’d think in the world of DIY and repairs, things would be straightforward. But the screw world is a labyrinth designed to trip up the unwary. Messing this up means your project won’t just look bad; it might not even hold together.
The Imperial vs. Metric Mess: Why Sizes Differ
Alright, let’s cut to the chase. The biggest reason why ’10 x 24′ and ‘5 x 80’ are not the same is that they come from two completely different measurement systems: Imperial (or US customary) and Metric. Think of it like trying to compare apples and… well, metric apples. They might both be fruit, but the way you describe them, their size, and how you use them is fundamentally different.
The ’10 x 24′ is your typical US-based measurement. The ’10’ refers to the nominal diameter of the screw, but it’s not a direct measurement in inches. Instead, it’s a gauge size. For machine screws, a size ’10’ is roughly equivalent to a diameter of about 0.190 inches (or 3/16 inch). The ’24’ is the thread pitch, meaning there are 24 threads per inch of screw length. This is a pretty common size for many household items, electronics, and general-purpose fastening.
Now, the ‘5 x 80’ is a metric measurement. The ‘5’ is the diameter of the screw in millimeters.
So, this screw is 5 millimeters across its widest point. That’s roughly 0.197 inches. See?
Pretty close to the ’10’ gauge in diameter, which is where the confusion often starts. But the ’80’ is the thread pitch, also in millimeters. This means there are 80 threads per 100 millimeters of screw length. This is a finer thread pitch than the 24 threads per inch on the US screw.
To convert 80 threads per 100mm to threads per inch, you’d divide 25.4 (mm per inch) by 100mm, then multiply by 80 threads. Or, more simply, just know it’s a much finer thread.
This finer pitch is common in metric countries for precision applications or where a more secure, less prone-to-vibration connection is needed.
So, while the diameters are very close (0.190 inches vs. 0.197 inches), the thread pitches are wildly different. Trying to force a 10 x 24 screw into a 5 x 80 nut, or vice versa, is like trying to screw a square peg into a round hole. It just won’t go, and if you force it, you’ll strip the threads on both the screw and the mating part, rendering both useless. I learned this the hard way when I tried to replace a screw on an old stereo receiver that had metric threads. I grabbed a US-made screw from my overflowing junk bin, and it wouldn’t even start threading. Frustrating doesn’t even begin to cover it.
What to Look for: Beyond the Numbers
So, you know they’re different. But what exactly should you be looking for when you’re at the hardware store or sifting through that chaos in your toolbox? It’s not just about memorizing numbers; it’s about understanding the characteristics of a screw. The key elements are diameter, thread pitch, thread type, length, and material.
Diameter: As we discussed, this is the first number. For ’10 x 24′, it’s the gauge size that translates to about 0.190 inches. For ‘5 x 80’, it’s 5 millimeters. They are close, but not identical. If you’re just eyeballing it, you might be fooled, but a caliper or even a good ruler with fine markings will show the difference. Always measure if you’re unsure.
Thread Pitch: This is the second number. For ’10 x 24′, it’s 24 threads per inch (TPI). For ‘5 x 80’, it’s 80 threads per 100 millimeters. This is the more important difference for compatibility. A screw with a finer thread pitch (like the 5 x 80) will have more threads packed into the same length compared to a coarser thread pitch (like the 10 x 24). If the threads don’t match, they won’t mate. This is true for both machine screws and bolts. (See Also: Can I Use Galvanized Deck Screws Instead Of Stainless Steel )
Thread Type: While both ’10 x 24′ and ‘5 x 80’ are machine screws, meaning they have uniform threads along the shank and are designed to be used with nuts or tapped holes, there are variations within these types. For example, some machine screws have a full thread (threads all the way up to the head), while others have a partial thread, leaving a smooth shank near the head. This affects how the screw seats against the surface. Also, the actual shape of the thread (the angle of the crest and root) can differ slightly between Imperial and Metric standards, though often they are designed to be compatible enough for a basic fit if the pitch and diameter are correct.
Length: This is usually straightforward. For Imperial screws, length is typically measured in inches. For Metric, it’s in millimeters. Some US manufacturers might list length in fractions of an inch (e.g., 1 inch, 1.5 inches), while others use decimals. Metric lengths will always be in whole millimeters or sometimes half-millimeters.
Material and Head Type: These are secondary considerations for compatibility but important for the application. Screws come in steel (often zinc-plated, brass, stainless steel, etc.) and have different head types (pan, round, flat, hex, security). While these don’t affect whether a 10 x 24 will fit a 5 x 80 nut, they are vital for the overall function and appearance of your repair or build. Always match the material to the environment to prevent corrosion and make sure sufficient strength.
Common Mistakes and What They Cost
Look, we’ve all been there. You’re halfway through a project, you’ve got a stripped screw head, or you’ve lost one and need a replacement now. The temptation to just grab ‘something that looks about right’ is immense. But this is where you really start to burn money and time.
The most common mistake is assuming that because two screws look similar in diameter, they’ll work. This is especially true when you’re dealing with the close diameters of Imperial and Metric screws.
You grab a 10 x 24, it almost starts to thread into a hole meant for a 5 x 80, and you give it a good shove. What happens? You mangle the threads. The screw might go in a bit, but it’s not secure.
Worse, you’ve likely damaged the threads in the nut or the tapped hole. Now you’ve got a dual problem: you need a new screw, and you need to figure out how to re-thread or replace the damaged part. This can involve buying thread chasers, taps and dies, or even entire replacement components, easily costing you $50 to $100 more than just buying the correct screw in the first place. And the time wasted?
Forget about it.
Another mistake is not checking the thread pitch properly. You might have a screw with the correct diameter but the wrong pitch.
For example, a 10-32 screw has the same diameter as a 10-24 screw but a finer thread pitch (32 threads per inch). If you try to use a 10-32 in a 10-24 nut, it won’t thread properly, or if it does, it will be a very loose, insecure fit.
Similarly, trying to jam a coarse thread metric screw into a fine thread metric nut, or vice-versa, will lead to the same thread-mangling disaster. The metric system has common thread pitches like M5 x 0.8 (which is close to the 5 x 80, but not exactly) and M5 x 0.9.
My personal screw-up involved trying to repair a vintage lamp. It had metric screws holding the base to the stem. I, in my infinite wisdom, used a box of assorted US machine screws. I found one that was the right length and looked right diameter-wise. It went in a few turns, felt a little tight, but I figured that was good – a snug fit. About a week later, the lamp fell over because the screw had worked its way loose and stripped the cheap pot metal nut. The repair cost me $30 for a replacement nut and a trip to the hardware store, plus the embarrassment. That was a cheap lesson compared to what some people end up paying. (See Also: Can Machine Screws Be Used In Wood )
A Quick Comparison Table
| Feature | 10 x 24 Machine Screw | 5 x 80 Machine Screw | Verdict |
|---|---|---|---|
| Diameter System | Imperial (Gauge Size) | Metric (mm) | Fundamentally different systems. |
| Nominal Diameter | Gauge 10 (~0.190 inches) | 5 mm (~0.197 inches) | Close, but not identical. Metric is slightly larger. |
| Thread Pitch System | Imperial (Threads Per Inch – TPI) | Metric (Threads Per 100mm) | Requires different nuts/tapped holes. |
| Thread Pitch Value | 24 TPI | 80 threads / 100mm | Significantly different. 5×80 has a much finer thread. |
| Compatibility | Requires 10 x 24 nuts/holes. | Requires 5 x 80 nuts/holes. | Absolutely NOT interchangeable. |
| Common Applications | Electronics, furniture, general household repairs (US). | Many imported electronics, appliances, machinery (metric). | Depends on the origin of the device. |
When Are They Not the Same? Practical Applications
So, beyond the technical specifications, where do you actually encounter these different screw types, and why does it matter? It boils down to the origin of the equipment you’re working on. If it was made in the United States, there’s a high probability it uses Imperial-sized fasteners like the 10 x 24. If it was manufactured in Europe, Asia, or anywhere else that primarily uses the Metric system, you’re going to be dealing with metric fasteners, such as the 5 x 80.
Let’s talk real-world scenarios. You’re assembling a piece of furniture from a US company. Chances are, the screws holding the drawer slides, the hinges, or the decorative trim will be Imperial. Maybe they’re 10 x 24, or perhaps 8 x 32, or 1/4-20 bolts. If you lose one or need to tighten something, you’ll need to match that specific Imperial size. A 10 x 24 screw is common for things like securing electrical outlet covers or attaching small brackets on electronics. You’ll also find them in some older toys or small appliances.
On the flip side, consider that imported TV mount you bought, or the foreign-made appliance. Those screws holding the VESA mounting plate to your TV, or the small screws securing the casing on a piece of audio equipment from Japan or Germany, are almost certainly metric. A 5 x 80 screw might be used for attaching small components inside electronic devices where a fine, secure thread is needed, or for securing panels on machinery. You’ll find metric screws in the precise measurements often used in automotive applications outside the US, and in many consumer electronics that are manufactured globally.
One of the trickiest areas is when you’re dealing with a mix. Some products, especially those designed for a global market, might use a combination of fasteners. You might have an American-designed product assembled with some US-made components and some imported metric ones. This is where having a good set of calipers and a basic understanding of thread identification becomes invaluable.
I once spent an hour trying to figure out why a particular panel on a high-end projector wouldn’t sit flush, only to discover that one of the securing screws was a metric fine thread and the other was a coarse thread. The slight difference in thread pitch was causing an angle, and I was fighting it instead of just getting the right screw.
If you’re not sure, the best approach is to try and identify the original screw. If it has any markings on the head, that’s a start.
Often, manufacturers will stamp the size directly onto the screw head. For example, you might see ’10-24′ or ‘M5 x 0.8’.
If there are no markings, you’ll need to measure. A digital caliper is your best friend here.
Measure the diameter across the threads, then try to count the threads per inch or per centimeter. You can do this by laying the screw flat on a ruler or using a thread gauge. If you still can’t figure it out, take the screw (or the part it came out of) to a well-stocked hardware store. They usually have experienced staff who can help you identify it, and they often have a ‘screw finder’ board where you can test different thread sizes.
When a Direct Swap Is a Disaster
I cannot stress this enough: you absolutely cannot directly swap a 10 x 24 screw for a 5 x 80, or vice versa. It’s not just about thread pitch; it’s about the entire system of measurement and manufacturing standards. It’s like trying to use US currency to buy something priced in Euros without converting. It just doesn’t work.
The core problem, as we’ve hammered home, is the thread pitch and diameter difference. Imagine trying to screw a 10 x 24 screw into a nut designed for a 5 x 80. The 10 x 24 has a coarser thread. It might start to engage a few threads of the 5 x 80 nut, but those threads are designed for a finer pitch.
As you try to turn it, the angled surfaces of the threads will rub against each other incorrectly. It won’t seat properly. You’ll feel resistance, and if you push it, you’ll start to deform both the screw threads and the nut threads. This is often called ‘cross-threading.’ (See Also: Can I Use Wood Screws For Durock )
It’s a messy situation because the screw won’t be secure, and the nut might be damaged to the point where it can’t accept the correct screw later on.
Conversely, trying to put a 5 x 80 screw into a 10 x 24 nut is also a disaster waiting to happen. The 5 x 80 has a finer thread. It might seem like it’s going in easily at first because the diameter is close. However, the finer threads of the 5 x 80 won’t properly engage with the coarser threads of the 10 x 24 nut. You’ll end up with a connection that feels loose and insecure, even if the screw goes all the way in. It’s not the right fit, and it won’t hold the intended load. This is particularly dangerous for structural components or anything under stress.
The temptation to force it is strong when you’re in a bind. I’ve seen people use pliers to try and jam the wrong screw in, or even try to ‘cut’ new threads with the wrong screw. This usually ends up with broken tools, stripped fasteners, and a project that’s worse off than when you started. The cost of a single correct screw is pennies or a couple of dollars. The cost of repairing damaged components, buying new tools (like taps and dies), or replacing a whole assembly can run into hundreds of dollars. Plus, the time you spend undoing the damage is exponentially more than the time it would have taken to find the right part initially.
My friend once tried to fix a loose handle on his power saw. He couldn’t find the exact metric screw it called for, so he used a slightly larger US machine screw. He managed to get it in, but the handle vibrated loose again within an hour.
Turns out, he’d stripped the threads in the saw’s housing. He ended up having to drill out the hole, tap it for a larger metric bolt, and install a new, much beefier bolt. What should have been a 5-minute fix turned into a two-hour ordeal with a trip to the auto parts store for a tap and die set. All because he wouldn’t accept that the 10 x 24 (or whatever he used) and the original metric were not the same.
Are Metric and Us Screws Interchangeable?
No, metric and US (Imperial) screws are generally not interchangeable. While some diameters might be very close, their thread pitches (threads per inch for US, threads per 100mm for metric) are different, meaning they will not mate correctly. Forcing them can damage both the screw and the receiving thread.
What Does 10 X 24 Mean on a Screw?
For a 10 x 24 machine screw, the ’10’ is a gauge size indicating the nominal diameter (approximately 0.190 inches), and the ’24’ indicates the thread pitch, meaning there are 24 threads per inch of length. This is a common US standard size.
What Does 5 X 80 Mean on a Screw?
For a 5 x 80 machine screw, the ‘5’ is the diameter of the screw in millimeters (5mm), and the ’80’ indicates the thread pitch, meaning there are 80 threads per 100 millimeters of screw length. This is a metric standard size with a finer thread pitch than a 10 x 24.
Can I Use a 5mm Screw Instead of a 10-24?
No. While a 5mm screw (like a 5 x 0.8 or 5 x 0.9 metric) has a diameter close to a 10-24 (which is about 0.190 inches, and 5mm is about 0.197 inches), their thread pitches are completely different. A 10-24 has 24 threads per inch, while common metric 5mm screws have pitches like 0.8mm or 0.9mm per thread. They are not compatible.
How Do I Know If I Have a Metric or Us Screw?
Look for markings on the screw head. US screws are often marked with their gauge size (e.g., ’10-24′) or a grade marking. Metric screws are typically marked with ‘M’ followed by the diameter and pitch (e.g., ‘M5 x 0.8’). If there are no markings, measure the diameter and count the threads per inch or per 100mm. Online charts and hardware store staff can help with identification.
Final Thoughts
So, to put it plainly, no, are 10 x 24 and 5 x 80 machine screws the same? Not even close. They belong to different measurement families and have different thread pitches, making them incompatible. Trying to mix them is a recipe for stripped threads, damaged parts, and wasted money.
Always double-check the specifications of the screw you need. If you’re unsure, measure it. A few minutes spent identifying the correct size and type will save you hours of frustration and the cost of repairs down the line. Your projects will be sturdier, and your toolbox won’t be filled with the mismatched, mangled remains of failed attempts.
Next time you’re staring at a pile of fasteners, grab a caliper and know your numbers. It’s the simplest way to avoid turning a small repair into a big headache.
