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8 inches is 20.32 centimeters (203.2 mm), or two thirds of a foot. It is the short side of an 8 × 10 photo, and about the height of a standard concrete block, which is actually 7⅝ inches tall.
8 inches in cm, mm and feet
Multiply by 2.54: 8 × 2.54 = 20.32 cm. That is why 8 inches is often rounded to 20 cm, but the exact value is 20.32 cm, about a third of a centimeter more.
| Inches | Centimeters | Millimeters | Feet | Yards |
|---|---|---|---|---|
| 7 ½ | 19.05 | 190.5 | 0.63 | 0.21 |
| 7 ¾ | 19.69 | 196.9 | 0.65 | 0.22 |
| 8 | 20.32 | 203.2 | 0.67 | 0.22 |
| 8 ¼ | 20.96 | 209.6 | 0.69 | 0.23 |
| 8 ½ | 21.59 | 215.9 | 0.71 | 0.24 |
Measured across the top or the rim
Pans, speakers and telescope mirrors are round or square, and their “8 inches” is a width. Where exactly the tape goes depends on the product.
1. An 8 × 8 Square Baking Pan
The 8 × 8 is the standard brownie and snack-cake pan. Bakeware is sized across the top inside edge, so the pan measures 8 inches on each side at the rim and a little less at the bottom, where the sides slope in.
Its surface is 64 square inches, a little more than half of a 9 × 13 pan (117 square inches). That is why recipes for a 9 × 13 pan are usually halved for an 8 × 8.
2. An 8-Inch Frying Pan
Skillets and frying pans are sold by the diameter of the rim, not the flat cooking surface. On an 8-inch pan, the flat bottom is often closer to 6 inches across, because the sides flare out.
It is the right size for two eggs or a single omelet. For a family breakfast, most cooks reach for a 10- or 12-inch pan.
3. An 8-Inch Subwoofer
Speaker sizes are nominal. An “8-inch” subwoofer has a frame about 8 inches across, and the moving cone inside is smaller. Check the cutout diameter in the specs before you cut a box or a panel.
8-inch subs are popular in cars because they fit under seats and in compact enclosures, trading some deep bass for space.
4. An 8-Inch Telescope Mirror
Telescopes are named by aperture, the diameter of the main mirror or lens. An “8-inch Dobsonian” has an 8-inch (203.2 mm) mirror. It is one of the most popular sizes for serious beginners.
Aperture is what matters most: an 8-inch mirror collects roughly 840 times more light than a dark-adapted human eye, enough to show Saturn’s rings and many galaxies.
Measured end to end
5. An 8-Inch Adjustable Wrench
Adjustable wrenches are named for their overall length, and 8 inches is the most common household size. Its jaws open to roughly an inch, enough for most nuts and plumbing fittings around the house.
The longer the wrench, the more leverage it gives you: a 10- or 12-inch wrench is easier on stubborn bolts.
6. An 8-Inch Zip Tie
Cable ties are sold by overall length, from the head to the tip of the tail. The 8-inch size is the everyday one in most multipacks, long enough to bundle cords behind a desk or TV.
Packages also list a tensile strength; standard 8-inch ties are commonly rated around 40 to 50 pounds.
7. An 8-Inch Bracelet
Bracelets are measured end to end with the clasp included. 8 inches is a common men’s length, while 7 inches is the usual women’s size.
To find yours, measure your wrist snugly and add about half an inch to an inch, depending on how loose you like it.
Measured center to center
8. An 8-Inch Widespread Faucet
A widespread bathroom faucet has three separate pieces: a spout and two handles. It is sized by the distance between the centers of the two handle holes, and 8 inches is the most common spread.
Many widespread faucets can stretch from about 6 to 16 inches, but 8 inches is the spacing most sinks and vanity tops are drilled for. The other common type, the centerset faucet, puts everything on one base with 4 inches between the handles. Count and measure the holes in your sink before you buy a replacement.
Nominal sizes: when “8 inches” is not 8 inches
9. An “8-Inch” Concrete Block
The standard concrete block is called 8 × 8 × 16, but it actually measures 7⅝ × 7⅝ × 15⅝ inches. The missing 3/8 inch is the mortar joint: once a block is laid, block plus mortar comes back to exactly 8 × 16 inches.
That makes wall layout simple. Every block, with its joint, takes up 8 inches of height and 16 inches of length.
Measured in height
10. An 8-Inch Bed Riser
Bed risers are sold by how much they lift the furniture, and 8 inches is one of the tallest common sizes. It is a popular way to fit storage bins under a bed.
Taller risers make a bed less stable, so check the weight rating and make sure each leg sits fully in its cup.
Paper and photos
11. An 8 × 10 Photo Print
The 8 × 10 is the classic portrait and headshot size. Its short side is exactly 8 inches; the long side is 10.
Framed with a mat, an 8 × 10 usually goes into an 11 × 14 frame, which leaves a mat border of 1.5 inches on two sides and 2 inches on the other two. A portrait Instagram post has exactly the same 4:5 shape; see Instagram post size in inches for how sharp it prints.
12. A Sheet of US Letter Paper
Standard US Letter paper is 8.5 × 11 inches, so its short side runs half an inch past 8 inches. It is the easiest 8-inch check in any office: fold over a half-inch strip and the rest is exactly 8 inches wide.
International A4 paper is a little narrower, at 8.27 inches, so it is even closer to 8 inches.
8 inches on your hand
For many adults, the hand span, from the tip of the thumb to the tip of the pinky with the fingers spread wide, is roughly 7 to 9 inches. So for many people, 8 inches is about one full hand span. Measure yours once against a sheet of Letter paper so you know your own number.
8 inches in diameter
A circle 8 inches across has a circumference of 25.13 inches (63.84 cm) and an area of 50.27 square inches (324.29 cm²). A 10-inch circle is only 2 inches wider, but its area is 56% larger.
8 inches vs. 10 and 12 inches
Three comparisons come up again and again in searches, and they all hinge on the same fact: for anything round or square, the area grows with the square of the width.
- 8-inch vs. 10-inch cake: a 10-inch round has 56% more surface than an 8-inch round, so it feeds about half again as many people at the same slice size.
- 8-inch vs. 12-inch pizza: a 12-inch pizza is only 4 inches wider, but it has 2.25 times the area of an 8-inch pizza. Two 8-inch pizzas are still less food than one 12-inch.
- 8-inch vs. 10-inch mattress: here the number is thickness, not width. An 8-inch mattress is a common choice for guest rooms, kids’ beds and daybeds, while 10 to 12 inches is typical for an adult’s main bed.
So when a recipe, a menu or a store page jumps from 8 to 10 or 12 inches, expect a much bigger change than the number suggests, except for mattresses, where the extra 2 inches is mostly extra comfort layer.
8 inches vs. nearby sizes
| Length | In cm | Everyday example |
|---|---|---|
| 6 in | 15.24 cm | A 6-inch sub |
| 7 in | 17.78 cm | A 5 × 7 photo, long side |
| 8 in | 20.32 cm | An 8 × 10 photo, short side |
| 9 in | 22.86 cm | A standard pie plate |
| 10 in | 25.4 cm | An 8 × 10 photo, long side |
How to measure 8 inches without a ruler
- A sheet of Letter paper: the short side is 8.5 inches, so fold over a half-inch strip.
- An 8 × 10 photo: the short side is exactly 8 inches.
- A dollar bill plus a little: a US bill is 6.14 inches long, so add about 1⅞ inches.
- Your hand span: roughly 8 inches for many adults, once you have checked yours.
More sizes to compare
- What 6 inches looks like: 15.24 cm, from a 6-inch sub to 6 inches of snow
- 20 cm in inches: 7.87 in, just under 8 inches
- What 9 inches looks like: 22.86 cm, from a pie dish to a paint roller
- What 10 inches looks like: 25.4 cm, from a saw blade to a 10-inch rough-in toilet
- Inches to cm converter: any length in inches, with a 1–100 inch chart and fractions
FAQs
8 inches is exactly 20.32 cm, or 203.2 mm.
Almost. 8 inches is 20.32 cm, about a third of a centimeter more than 20 cm. A length of 20 cm is 7.87 inches.
A foot is 12 inches, so 1.5 lengths of 8 inches make a foot. 8 inches is two thirds of a foot.
Concrete blocks are made 3/8 inch smaller than their nominal size so that a standard mortar joint brings each block back to exactly 8 × 16 inches in the wall.
Across the top inside edge. For a frying pan, that means the rim, so the flat cooking surface is smaller, often around 6 inches.
8 inches is 2/3 of a foot, or about 0.67 feet.
Looking for a smaller size? See what 6 inches looks like, or convert any length with the inches to cm converter.