How long is 20 cm? It is exactly 200 millimeters, 0.2 meters, or about 7.87 inches. That is slightly narrower than the short side of an A4 sheet of paper.
A number on its own rarely helps. You can read “20 cm” on a product page and still not know whether the item fits your bag, your drawer, or your hand.
This guide fixes that. You will find a full conversion table, 18 everyday objects, no-ruler tricks, and a comparison with 15, 25, and 30 cm. By the end, you will know how long is 20 cm at a glance.
Quick answer: 20 cm = 200 mm = 0.2 m ≈ 7.87 in ≈ 0.66 ft
20 cm in Every Measurement Unit: Complete Conversion Guide
The centimeter is a handy middle unit. It is small enough for everyday objects but large enough to avoid long strings of digits. Here is 20 cm in every unit you are likely to need.
| Unit | 20 cm equals | How to convert |
| Millimeters (mm) | 200 mm | cm × 10 |
| Meters (m) | 0.2 m | cm ÷ 100 |
| Kilometers (km) | 0.0002 km | cm ÷ 100,000 |
| Micrometers (µm) | 200,000 µm | cm × 10,000 |
| Inches (in) | 7.87 in | cm ÷ 2.54 |
| Feet (ft) | 0.656 ft | cm ÷ 30.48 |
| Feet and inches | 0 ft 7 7/8 in | Fraction rounded to the nearest eighth |
| Yards (yd) | 0.219 yd | cm ÷ 91.44 |
Three formulas cover most situations:
- Centimeters to millimeters: multiply by 10.
- Centimeters to inches: divide by 2.54.
- Centimeters to feet: divide by 30.48.
One inch is defined as exactly 2.54 cm, so the conversion is precise. Only the rounding changes from site to site, which is why you will see 7.87 and 7.874 used interchangeably.
These figures answer the technical side of how long is 20 cm. The next section covers the visual side.
18 Everyday Objects That Help You Visualize 20 cm
Numbers are precise, but objects are memorable. The list below uses things you probably own or see daily.
Some match 20 cm almost exactly, while others run a little long or short. I note the gap each time so you can adjust your mental ruler.
Sizes vary by brand and country, so treat every figure as an approximation. If you need a quick way to picture how long is 20 cm, this list is the fastest route.
1. A Folded Newspaper Measuring Around 20 cm Wide
A tabloid newspaper opens to roughly 28 cm by 40 cm. Fold it once across the middle and the panel is about 20 cm deep. Publishers use different page sizes, so measure your own copy once and remember it.
2. A Standard Unsharpened HB Pencil
A new HB pencil measures about 19 cm, which is only 1 cm shy of the target. It is the classic stand-in for 20 cm. Next time a friend asks how long is 20 cm, hold up a pencil. Sharpening shortens it by a few centimeters, so use a fresh one.
3. A Men’s Dress Shoe in UK Size 8 or EU Size 42
This one is a comparison rather than a match. A UK 8 / EU 42 dress shoe is usually 29–30 cm long on the outside. So 20 cm is about two-thirds of the shoe, running from the heel to the front of the arch. Insole length is shorter, around 27 cm, so always measure the outside.
4. The Height of a Trade Paperback Novel
Many trade paperbacks use a 5.25 × 8 inch format, which is 13.3 × 20.3 cm. Others run up to 23 cm tall. Stand a book upright and you have a handy answer to how long is 20 cm. Mass-market paperbacks are smaller, at about 17–18 cm.
5. A Wooden Cooking Spoon Measuring Close to 20 cm
Full-size serving spoons run about 30 cm. Smaller tasting spoons and compact stirring spoons often land between 18 and 22 cm. Check your drawer for a short one. Most kitchens have at least one.
6. The Diagonal of a Compact Tablet Screen
A 7.9-inch tablet screen measures about 20.1 cm corner to corner. Screen sizes are quoted as diagonals, so multiply inches by 2.54 to get centimeters. Only the display counts here, not the bezel around it.
7. A Standard DL Envelope
A DL envelope is 110 × 220 mm, so it is 22 cm long. That is 2 cm more than our target, and the width is only 11 cm. It is useful because a letter folded in thirds fits inside it.
8. A Newborn Baby’s Foot Length
A newborn’s foot is about 7–8 cm long. Line up two and a half to three of them heel to toe and you reach 20 cm. It is a gentle way to picture how long is 20 cm for new parents.
9. A Tall 500 ml Craft Beer Can
A 500 ml can stands about 17 cm tall, so you need roughly 3 cm more. It works as a “nearly there” reference. A 440 ml can is a little shorter, so check the volume.
10. A Personal Pizza With a 20 cm Diameter
An 8-inch personal pizza is 20.3 cm across. This is one of the best circular references, and a later section covers it in detail.
11. The Height of a Hardcover Children’s Book
Many picture books stand 20–23 cm tall. Square 8 × 8 inch formats measure 20.3 cm on every side. Grab one from a kid’s shelf and you have a ready reference.
12. The Length of a Standard House Brick
A UK brick is 21.5 cm long. A US modular brick is about 19.4 cm. So 20 cm sits right between them. Builders judge how long is 20 cm by eye with this kind of unit all day.
13. The Blade of an 8-Inch Chef’s Knife
An 8-inch chef’s knife has a blade of about 20.3 cm. The handle adds roughly 12 cm. This is a sharp object, so use it for imagining only. Never use it as a ruler.
14. The Width of an A4 Sheet of Paper
An A4 sheet is 21 cm wide and 29.7 cm long. The short side is just 1 cm longer than 20 cm. US Letter paper is 21.6 cm wide, so the same trick works with a bit more margin.
15. A Full-Size Dinner Fork
Dinner forks usually measure 19–21 cm. Hold one next to your pencil and you will see they match closely. Dessert forks are shorter, at about 15–17 cm.
16. A Large Banana Measuring Close to 20 cm
A medium banana is about 18 cm. Large ones measure 20–23 cm along the curve, peel included. It is not the most precise reference, but it is the one people remember.
Next time you wonder how long is 20 cm at breakfast, grab a banana.
17. The Length of an Adult Hand From Wrist to Fingertip
Measured from the wrist crease to the middle fingertip, the average adult hand is about 17–19 cm.
Women’s hands average near 17 cm and men’s near 19 cm. Large hands reach 20 cm, so measure yours once with a ruler.
18. The Diameter of a Small Salad or Side Plate
Side plates usually measure 18–20 cm across, and salad plates up to 22 cm. Put one on the table and you can picture how long is 20 cm across a circle.
How to Estimate 20 cm Without a Ruler: Easy Alternatives
No ruler nearby? You can still land within a centimeter or two. Here are five quick methods.
- Use an A4 sheet. The short side is 21 cm. Mentally trim 1 cm and you have 20.
- Stack credit cards. A bank card is 8.56 cm long. Two cards give 17.1 cm, and 2.3 cards reach 20 cm.
- Compare with a US dollar bill. It is 15.6 cm long. Add about 4.4 cm, roughly the width of a matchbox.
- Use your phone. Most phones are 14–16 cm long. Add about a third of a phone’s length.
- Use a string and mark. Cut a string to match a known 20 cm item, such as a pencil plus 1 cm, and keep it in your toolbox.
Wondering how long is 20 cm when you have no tools? Keep one reference in your wallet or bag. A bank card is perfect, because it is the same size everywhere.
Expect an error of about ±1 cm with these tricks. That is fine for shopping or planning, but not for cutting or fitting.
The 20 cm Pizza Size: Diameter, Radius, and What to Know
A 20 cm pizza is roughly an 8-inch pizza. Many shops sell it as a “personal” or “small” size.
Here are the key numbers:
- Diameter: 20 cm (7.87 in)
- Radius: 10 cm
- Circumference: about 62.8 cm
- Area: about 314 cm²
A pizza shows how long is 20 cm better than almost any object, because you see it across the whole circle.
Area grows faster than diameter, which surprises many people. Compare common sizes below.
| Pizza diameter | Inches | Radius | Area |
| 15 cm | 5.9 in | 7.5 cm | 177 cm² |
| 20 cm | 7.9 in | 10 cm | 314 cm² |
| 25 cm | 9.8 in | 12.5 cm | 491 cm² |
| 30 cm | 11.8 in | 15 cm | 707 cm² |
A 30 cm pizza has 2.25 times the area of a 20 cm one. So two small pizzas hold less food than one 30 cm pizza.
A 20 cm pizza suits one hungry person, or two with sides, and it usually cuts into four to six slices.
How Long Is 20 cm in Inches? Quick Conversion
How long is 20 cm in inches? Divide by 2.54: 20 ÷ 2.54 = 7.874 inches. Rounded, that is 7.87 inches, or 7 7/8 inches on a tape measure.
Here is a handy reference for nearby values:
| Centimeters | Inches |
| 5 cm | 1.97 in |
| 10 cm | 3.94 in |
| 15 cm | 5.91 in |
| 20 cm | 7.87 in |
| 25 cm | 9.84 in |
| 30 cm | 11.81 in |
If your tape measure only shows inches, look for the mark just before the 8-inch line. It sits about 1/8 inch short of 8.
What Does 20 cm Look Like in Real Life? Visual Size Comparisons
How long is 20 cm in real life? About one pencil, one dinner fork, or one outstretched hand. That is longer than a pen and shorter than a ruler.
Sorting objects into shorter, similar, and longer groups builds a mental scale quickly:
| Group | Object | Approx. length | Compared with 20 cm |
| Shorter | Bank card | 8.6 cm | Less than half |
| Shorter | Ballpoint pen | 14–15 cm | About 25% shorter |
| Shorter | Typical smartphone | 14–16 cm | About 20% shorter |
| Similar | HB pencil | 19 cm | Almost the same |
| Similar | Dinner fork | 19–21 cm | About the same |
| Similar | 8-inch pizza | 20.3 cm | Matches |
| Longer | A4 paper (long side) | 29.7 cm | About 50% longer |
| Longer | School ruler | 30 cm | 50% longer |
Notice the pattern: 20 cm is small enough to hold in one hand, but long enough to feel substantial. That is why it shows up in so many designs.
How Does 20 cm Compare With 15 cm, 25 cm, and 30 cm?
Comparing neighboring sizes sharpens your sense of scale. This is the clearest way to understand how long is 20 cm against lengths you already know.
| Length | Inches | Millimeters | Familiar object | Difference vs 20 cm |
| 15 cm | 5.91 in | 150 mm | US dollar bill | 5 cm shorter (25% less) |
| 20 cm | 7.87 in | 200 mm | HB pencil | Baseline |
| 25 cm | 9.84 in | 250 mm | Large dinner plate | 5 cm longer (25% more) |
| 30 cm | 11.81 in | 300 mm | School ruler | 10 cm longer (50% more) |
A few takeaways:
- 15 cm vs 20 cm: the gap is about the width of a matchbox.
- 25 cm vs 20 cm: the gap is roughly a credit card’s length.
- 30 cm vs 20 cm: a 30 cm ruler is exactly one and a half times as long.
Your hand span can help too. Most adults can stretch from thumb tip to little fingertip across 18–22 cm.
How to Measure 20 cm Using Your Hand or Common Household Items
For something a bit more reliable than guessing, try these methods.
Using your hand
- Place a ruler on a table and spread your hand over it.
- Note where your thumb tip and little fingertip land.
- Remember that number. For many adults it falls between 18 and 22 cm.
A hand measures 20 cm in a flash once calibrated. It is also the easiest trick for answering how long is 20 cm at a market stall or a fabric shop.
Using household items
- Four AA batteries: each is about 5 cm long, so four end to end give about 20.2 cm.
- A plastic drinking straw: standard straws are 20–21 cm long.
- A fresh HB pencil plus a thumb width: the pencil is about 19 cm, and a thumb adds roughly 2 cm.
Lay items on a flat surface and keep them straight. Even small gaps between objects can add up to a centimeter or more.
Is 20 cm Almost 8 Inches? Understanding the Exact Difference
Yes. Eight inches equals 20.32 cm, so 20 cm is 0.32 cm, or 3.2 mm, short of 8 inches. That is about 1.6% less.
To picture the gap, stack two US quarters. Their combined thickness is about 3.5 mm. That is all that separates 20 cm from 8 inches.
For everyday tasks, the two are interchangeable. You can call an 8-inch pizza 20 cm and nobody will argue. The difference matters in a few cases:
- Woodworking and engineering: a 3 mm error can ruin a joint.
- Sewing and tailoring: it can change how a seam sits.
- Product specs: a 20 cm slot may not fit an item listed as 8 inches.
Rule of thumb: when precision matters, convert exactly and round to the nearest millimeter. When it does not, treat 20 cm as “just under 8 inches.”
Frequently Asked Questions
How long is 20 cm?
It equals 200 millimeters, 0.2 meters, or about 7.87 inches.
How long is 20 cm in inches?
Divide 20 by 2.54 to get 7.87 inches, or about 7 7/8 on a tape measure.
Is 20 cm the same as 8 inches?
Not exactly. Eight inches is 20.32 cm, so 20 cm is about 3 mm shorter.
How many millimeters are in 20 cm?
There are 200 millimeters, since each centimeter is 10 mm.
How many feet is 20 cm?
About 0.656 feet, or roughly 7 7/8 inches.
What objects are about 20 cm long?
A new HB pencil, dinner fork, 8-inch chef’s knife blade, or an adult’s hand span.
How can I measure 20 cm without a ruler?
Use an A4 sheet’s short side (21 cm), minus 1 cm, or line up four AA batteries.
Is 20 cm long or short?
It is short compared with a 30 cm ruler, but longer than most pens and phones.
How big is a 20 cm pizza?
It has a 20 cm diameter, 10 cm radius, and about 314 cm² of surface, which is an 8-inch pizza.
Conclusion
So, how long is 20 cm? It is 200 millimeters, 7.87 inches, or about the length of a fresh pencil. A fork, a side plate, and an 8-inch pizza are all close matches.
Once you attach 20 cm to a few objects, estimating gets much easier. Keep a favorite reference in mind, whether it is a bank card, your hand span, or a four-battery line.
Whenever someone asks how long is 20 cm, you will have an answer that is both exact and easy to picture.
