You’re holding a part, a button, or a nut, and you’ve got no ruler. You wonder how long 1.375 inches really is, and which everyday objects can stand in for it.Here’s the short answer. 1.375 inches equals 1 3/8 inches, 3.49 centimeters, or 34.93 millimeters. That’s a bit more than a US quarter and a bit less than a ping pong ball.
Some objects match this measurement closely. Others only come near it, and I’ll tell you exactly where each one misses so you don’t get fooled.
Quick Conversion: 1.375 Inches
Let’s lock in the numbers first. This fractional measurement is eleven eighth-inch increments, which is why 1 3/8 inches and 11/8 inches describe the same length.
Here’s your quick reference for measurement conversion:
| Unit | Value |
| Inches to centimeters | 3.49 cm |
| Inches to millimeters | 34.93 mm |
| Inches to feet | 0.1146 feet |
| Inches to meters | 0.0349 meters |
| Inches to yards | 0.0382 yards |
| Inches to kilometers | 0.0000349 km |
| Inches to miles | 0.0000217 miles |
The metric system rounds this to about 35 mm in daily talk. That’s handy when a metric specification and an American measurement system tool meet on the same workbench.
Hardware and Tools That Measure 1.375 Inches
Walk down any hardware aisle and you’ll spot this size fast. Fasteners and tools use eighth-inch increments all the time, so 1 3/8 inches shows up more than you’d think.
Brands like Stanley and Everbilt sell sizes in these steps. Let’s look at two items people search for most.
Standard Hex Nut
A 1 3/8 inch wrench is a real size in American tooling increments. It fits a hex nut that measures 1.375 inches across the flats, which is the distance between two parallel sides.
Don’t confuse that with corner to corner, which runs longer. Check the across flats number on the package before you buy, because dimensional tolerances differ by grade.
Wood Screw Head Diameter
Here’s a reality check. Most wood screw heads sit well under one inch, so a true 1.375 inch screw head diameter is rare.
You’ll meet this size in oversized washer heads and in countersink tools that cut the recess for them. It’s common in deck construction and furniture assembly when you drill for plugs and covers.
Office Supplies Measuring 1.375 Inches
Your desk drawer works as a visual reference too. Office supplies use a metal wire frame or a clamp width that lands near this range.
Teachers, students, and office workers all grab these every day. Stores like Staples carry both items below.
Large Jumbo Paper Clip
A jumbo paper clip usually runs about 2 inches long, so 1.375 inches is roughly two thirds of its length. That makes it a useful physical reference for a partial measure.
Fold your finger along the wire and you’ll see how the frame width compares. It’s a fast way to check a margin on class handouts or student notebooks.
Medium Binder Clip
A medium binder clip from brands like Acco or Officemate typically opens to about 1.25 inches. That’s close, but it falls short by an eighth of an inch.
Use it as a rough measurement reference, then add a thin sliver to reach 1 3/8. Always confirm with a ruler measurement when the exact measurement matters.
Gaming and Entertainment Items That Are 1.375 Inches
Gaming equipment loves precise measurement. A tiny error changes how a throw or a roll behaves, so makers hold tight dimensional accuracy.
I’ll be straight with you on the first item. It’s a near miss, and it’s still a great way to picture the size.
Casino Precision Dice
Casino precision dice are cubes about 3/4 inch (19 mm) on each side. That’s smaller than our target, so they don’t equal 1.375 inches on their own.
Line two casino dice side by side and you get 1.5 inches. That’s a neat physical size comparison, and regulated gambling establishments in places like Las Vegas and Atlantic City use dice built to that standardized dimensions idea.
Steel-Tip Dart Tip
Many steel-tip dart points run roughly 1.25 to 1.5 inches, so one often sits near 1.375. The dart tip length changes by brand and set.
Makers like Winmau list their specs, and competition-grade darts vary between dart barrels and dart shafts. Measure your own set, since scoring consistency depends on how the whole dart balances.
Sports Equipment That Are 1.375 Inches Long
Sports equipment follows sporting standards, and those rules are strict. Here’s a pair where size shapes the game.
Just so you know, one of them overshoots our target and I’ll show you by how much.
Ping Pong Ball Diameter
A regulation table tennis ball measures 40 millimeters under International Table Tennis Federation rules. That’s about 1.575 inches, roughly 0.2 inches bigger than 1.375.
So a ping pong ball is a close visual cousin, not an exact match. Brands like JOOLA and Butterfly build to ITTF standards, which keeps a competitive match fair.
Castle Golf Tee Height
A castle golf tee is a stepped tee with a ball-resting cup on top. Short versions are sold for par-three holes and long iron approaches.
Their tee height is often in the 1.25 to 1.5 inch range, depending on the brand. Check the pack, because ball positioning and club face contact change with every eighth of an inch.
Food and Nature Objects Measuring 1.375 Inches
Your kitchen counter makes a fine ruler. Food and nature objects vary a little, so treat these as field estimates.
Still, they give you a zero-cost reference point you can picture instantly.
Large English Walnut
A large English walnut in the shell often measures around 1.25 to 1.5 inches across its equatorial point. That puts many jumbo grade nuts right near 1 3/8.
Walnut producers such as Diamond Nuts and Fisher use size sorting after harvest. Pick a few premium-grade walnuts and you’ll feel the match.
Jumbo Cerignola Olive
A jumbo Cerignola olive is a big Italian olive variety that often runs 1.25 to 1.5 inches from stem end to olive tip. You’ll find them in specialty grocery stores.
That interior cavity is why people love stuffing them with cheese, garlic, or almonds. The size grades go from jumbo to colossal olives and super colossal olives.
Electronics and Technology Components That Are 1.375 Inches
Electronics and technology components rely on production tolerances. Parts must fit every time, which is why device compatibility is such a big deal.
Both items below are everyday tech references, but only one comes close.
AA Battery Diameter
A standard AA battery is about 14.5 mm wide, roughly 0.57 inches. So the AA battery diameter is far from 1.375 inches.
Two side by side give you about 1.14 inches, and three give about 1.7. Battery manufacturers like Duracell and Energizer keep that cylindrical outer casing consistent across every batch.
Pill Bottle Cap Diameter
A prescription pill bottle cap often falls between 1.25 and 1.6 inches across, depending on the vial size. Many sit close to 1.375.
Pharmaceutical packaging teams design these around child-resistant safety. Pharmacy brands like CVS and Walgreens use a few cap sizes for prescription dispensing, so measure yours before you hunt for a replacement.
Personal and Fashion Items Measuring 1.375 Inches
Clothing hardware has its own size language. Sewing notions and garment design often use millimeters, which makes this one easy.
Large Coat Button
A large coat button of 35 mm is 1.378 inches, so it’s a near perfect match. Oversized coat buttons and jacket buttons usually fall between 28 and 38 mm.
You’ll see this coat button diameter on outerwear fashion pieces and fashion accessories. It also echoes the weighty look of 1940s American tailoring and 1950s American tailoring, when bold garment aesthetics were common.
How to Measure 1.375 Inches Without a Ruler
No ruler? You can still get close. Body-based measurement works as a quick estimate, though hands differ a lot.
Here’s a simple way to calibrate:
- Adult thumb knuckle width is often near 1 inch, so add a little more.
- Thumb width at the tip usually runs about 0.75 to 1 inch.
- Index finger plus middle finger side by side often reach about 1.25 to 1.5 inches.
Test each one against a real ruler once, then remember your own numbers. That turns your hand into a physical reference you can trust.
How to Find 1.375 Inches on a Ruler
Look at your measurement scale and find the one-inch mark. Now count three eighth-inch marks past it.
That’s your 1 3/8. For measuring exact dimensions, line up the edge of the object with zero and read where it ends, and don’t start from the ruler’s rim.
Why 1.375 Inches Matters in Manufacturing
This size isn’t a universal rule. It’s one clean step in eighth-inch increments, and American manufacturing uses those steps in product specifications and engineering specifications.
Manufacturing tolerances keep each production batch within a tiny range. That’s how universal compatibility works when parts come from different plants.
Conclusion
1.375 inches equals 1 3/8 inches, 34.93 millimeters, or 3.49 centimeters. Coat buttons, hex nut flats, and many walnuts, olives, and pill caps land right around it.
Ping pong balls, binder clips, and AA batteries miss by a bit, and that’s useful to know too. Which object helped you picture it best? Drop a comment, and share this with someone who’s guessing sizes right now.
FAQs
What is 1.375 inches in fraction form?
It’s 1 3/8 inches, which also equals 11/8 inches. You read it as one inch plus three eighths.
How can I measure 1.375 inches without a ruler?
Use a coat button of about 35 mm, or compare your index finger and middle finger width. Calibrate once against a real ruler for better field estimates.
Is 1.375 inches the same as 34.93 mm?
Yes, rounded to two decimals. The exact figure is 34.925 mm, so 34.93 mm is the standard rounding.
What common household items are exactly 1.375 inches?
Few items are exact, since real products vary. Large coat buttons, some walnuts, and certain pill bottle caps come very close.
Why is 1.375 inches a standard measurement in manufacturing?
It’s one common step in eighth-inch increments used in American tooling increments. It isn’t a universal standard, but it’s a familiar size in hardware components.
How do I find 1.375 inches on a ruler?
Find the one-inch mark, then count three eighth-inch marks further. That spot is 1 3/8 inches.
What sports equipment measures 1.375 inches?
Some castle golf tees and similar tee height options sit near this size. A table tennis ball is bigger at 40 mm, about 1.575 inches.
