How Long is 3.5 Mm? 19 Common Comparisons (+Pics)

Knowing the length of 3.5 mm is often relevant when dealing with technology, particularly audio equipment.

It can help you choose the right accessories, such as cables or adapters, for your devices with 3.5 mm audio jacks.

In this post, we delve into 19 common comparisons that will not only help you estimate the length of 3.5 mm but also visualize and comprehend its scale in various contexts.

Read: How Big is 200 Cubic Feet? 13 Common Comparisons 

Let’s dive in!

19 Common Comparisons For 3.5 Millimeters

1. A ⅙ diameter of a nickel


Nickels are an excellent reference for understanding tiny measurements due to their standardized size and widespread familiarity. They are commonly used in daily transactions and are integral to the United States currency system.

They usually have a diameter of about 21 mm.

So, 3.5 mm is a sixth of a nickel. 

2. A ⅙ diameter of a penny

Similarly to nickels, pennies are widely used in everyday transactions and are an integral part of the United States coinage system.

These coins are also almost as big as nickels, with a diameter of about 19.25 millimeters. 

Consequently, you can compare 3.5 mm to a sixth of a penny to understand its range.

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3. A ⅕ diameter of a dime

Dime is the smallest coin in the United States currency system in terms of physical size.

It has a diameter of about 18 mm.

One-fifth of this coin’s diameter is approximately 3.5 mm.

4. A stack of 2 US quarters

US quarters provide an excellent way to understand tiny measurements, including 3.5 mm. 

Since each US quarter is 1.75 mm thick, you can stack two to realize that measurement. 

Alternatively, since they are physically larger than nickels and pennies with a diameter of 24 mm, you can visualize 3.5 mm by considering that 3.5 mm is roughly one-seventh (1/7) of the quarter’s diameter.

5. A bundle of 35 US dollar notes

US dollar notes are commonly used for estimating measurements because they are readily available, widely recognized, and have standardized dimensions.

Regardless of the denomination, all US dollar notes are 0.0043 inches or about 0.1 millimeters thick. 

That means if you have a bundle of 35 notes, it’s a perfect reference for 3.5 mm.

6. A pile of 5 debit cards

All debit cards are equal for universal compatibility with card readers and payment terminals.

They’re usually 3.37 inches long, 2.125 inches wide, and around 0.03 inches (0.76 mm) thick.

So, if you pile as many as five debit cards, they would add up to 3.8 millimeters, close to the measurement you’re looking for. 

7. Half thickness of a no. 2 pencil

No. 2 pencils are a common type of pencil, widely used for various purposes, including writing, drawing, and standardized test-taking.

No. 2 pencils typically come in a standard size with a length of around 7. 5 inches and a barrel diameter of about 0.28 inches (7.1 mm).

Thus, you can visualize 3.5 mm by recognizing it as half the diameter of the pencil.

8. Three-quarters of a cap eraser

Cap erasers are erasers attached to the end of pencils.

Usually pink or white, cap erasers are often 5 millimeters big.

Three-quarters of these erasers are about 3.75 mm, but still a reliable reference for 3.5 mm. 

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9. Half the thickness of a ballpoint pen

Ballpoint pens commonly used in schools and other settings typically have a medium point size and a diameter of about nine millimeters. 

If you can find one, 3.5 mm is a little longer than half the diameter of that pen.

10. Half a standard staple

Staples are a staple office and stationery item often used in staplers to bind documents.

They come in various sizes, with standard ones measuring six millimeters most suitable for everyday needs. 

Half of that staple can give you a sense of 3.5 mm as it is only slightly longer than that.

11. A bunch of 35 copy papers

A copy paper is suitable for many office and personal printing needs, such as documents, reports, and everyday correspondence.

A standard copy paper is often 8.5 by 11 inches and 0.1 millimeters thick – just as United States dollar notes.

Consequently, if you pile as many 35 copy papers, you’d realize a size of 3.5 mm.

12. A ⅓ diameter of an AAA battery

AAA batteries are household items for powering devices like remote controls, flashlights, and small electronic gadgets.

They typically have a standardized cylindrical shape with a diameter of about 10.5 millimeters.

A third of their diameter equals precisely 3.5 mm.

13. A 1/7 diameter of a crown bottle cap

Crown caps that seal carbonated drinks, beer, and other bottled beverages are easy to find in most households.

They have standard sizes, with a diameter of around 28 millimeters, to ensure compatibility with most standard beverage bottles.

So, one-seventh of their diameter equals 3.5 mm.

14. A ⅕ of a standard dice

Dice are small, often cubical objects with numbered sides, typically used in various games of chance and strategy. 

They are available in different sizes, the most common being the six-sided, with numbers 1 through 6. It’s usually 16 mm on all sides. 

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So, 3.5 mm is one-fifth of the standard dice.

15. A pile of 3 CDs

CDs are yet to be phased out. They are popular in specific niches, and some enthusiasts appreciate the tangible aspect of physical media.

If you still have them at home, you only need a pile of three to realize a measurement of 3.5 mm since each is usually 1.2 mm thick.

If you have DVDs instead, you need as many as six since these are thinner, at 0.6 millimeters.

16. A ⅓ of your fingernail

Of course, the size of fingernails can vary among individuals depending on factors such as genetics, age, and overall health.

That said, according to Research Gate, the average is between 12.2 and 12.8 mm in women and men in all five fingers. 

So, you can visualize 3.5 mm as a little shorter than a third of your fingernail.

17. A 1/7 of your thumb

What if you use your thumb instead of fingernails? How can you visualize 3.5 mm? 

You can imagine dividing it into seven equal parts to get a sense of 3.5 mm since the average thumb is about 25 millimeters big.

Read: How Big is 300 Square Feet? 15 Common Comparisons (+Pics)

18. A ¼ regular black raisin

Raisins are dried grapes and come in various types, such as black, dark, and golden.

They’re also available in different sizes, with the regular black raisin the smallest at 1.5 cm or 15 mm. 

If you cut this raisin into four equal parts, each will be approximately 3.5 mm.

19. 7 granulated sugar grains

Granulated sugar, composed of fine crystals, is a versatile sweetener used in various culinary applications, from sweetening beverages to baking and cooking.

The size of granulated sugar grains is tiny and uniform, typically around 0.5 mm.

If you are at home, you can pick seven granulated sugar grains and arrange them end-to-end to realize how long 3.5 mm is.

About Kevin Jones

My name is Kevin Jones, and I'm the proud founder of this website. I'm a self-professed measurement enthusiast, and I've been passionate about measuring things for as long as I can remember. On this website, you'll find information on all aspects of dimensions, including measurements and weight of stuff.