So you’re staring at a product description that says “20 cm” and wondering what that actually means in inches. Been there. Done that. Too many times to count.
20 cm equals 7.87 inches.
There’s your answer. But hang on a second because I’m gonna walk you through why this matters and how you can stop second-guessing yourself every time you see centimeters.
Why This Conversion Matters More Than You Think
Last month I was buying picture frames on Amazon. The seller was from Germany, and everything was listed in centimeters. I saw “20 cm x 25 cm” and thought “yeah, that’s probably fine” without actually converting it.
Wrong move.
The frame showed up and it was way bigger than I expected. Turns out 20 cm is almost 8 inches, not the 5 or 6 inches I had pictured in my head. My fault entirely for not doing the basic math.
The reality? Most of us Americans grew up with inches, feet, and yards. We instinctively know what 8 inches looks like. But 20 centimeters? That’s abstract until you put in the work to convert it.
So when you’re searching “how many inches is 20 cm” you’re probably trying to figure out if something fits, right? Will this laptop sleeve work? Is this cutting board too big for my drawer? Does this plant pot fit on my shelf?
These are practical questions that need practical answers.
The Math Behind How Many Inches is 20 cm
There’s one number you gotta remember:
1 inch = 2.54 centimeters
That’s the conversion rate. Has been since 1959 when a bunch of countries got together and agreed on it. Before that, different places used slightly different definitions which sounds like a nightmare. You can check out NIST’s official definition if you want the technical details.
Anyway, here’s your calculation for figuring out how many inches is 20 cm:
Take 20 and divide it by 2.54
20 ÷ 2.54 = 7.874015748 inches
Yeah, that’s a lot of decimals. Nobody uses all those. Round it to 7.87 and you’re golden for pretty much everything except maybe NASA missions.
Some people go with 7.9 inches. Others just say 8 inches and call it a day. Depends what you’re doing with the measurement.
Let Me Paint You a Picture
Numbers by themselves? Useless. What does 20 cm actually look like in the real world?
Grab your smartphone right now. Most phones are between 15 and 20 cm tall. Mine’s an iPhone 13 and it’s 14.67 cm, so 20 cm would be a bit taller than that.
Or think about a standard dinner plate. Most are right around 20 to 25 cm across. So 20 cm is basically the diameter of a dinner plate.
Here are some other things that are roughly 20 cm:
- The width of a regular sheet of paper (it’s actually 21.6 cm but close enough)
- A TV remote control (most are between 18-22 cm depending on the brand)
- Your hand stretched from the base of your palm to your middle fingertip if you’ve got average-sized hands
- A subway sandwich – the 6-inch one is close, but 20 cm is actually a bit longer at nearly 8 inches
- A new, unsharpened pencil is usually 19 cm, so just slightly shorter
Once you’ve got these visual anchors in your brain? Asking “how many inches is 20 cm” becomes less about math and more about recognition. You’ll start to just… know.
The Backwards Conversion (Because You’ll Need It)
Sometimes you go the opposite direction. You’ve got a measurement in inches and somebody wants centimeters.
That formula is even easier:
Inches × 2.54 = Centimeters
So let’s verify our 20 cm conversion: 7.87 inches × 2.54 = 19.99 centimeters
Close enough to 20 that we know we did it right.
I use this backwards check constantly. Like when I’m cutting fabric or wood and I want to make absolutely sure I didn’t screw up the conversion. Better to spend 10 extra seconds checking than to waste materials, you know?
Real Talk: When You Actually Need This
My cousin works in e-commerce and he says the number one reason for returns on international products? Size expectations. People see “20 cm” and just… guess. They don’t convert it. Then they’re shocked when the item arrives.
Here’s where this conversion shows up all the time:
Online shopping from international sellers – European websites, Asian electronics retailers, Australian home goods stores. They all use metric. You need to know how many inches is 20 cm or you’re flying blind.
Following recipes – I love watching British cooking shows on YouTube. When they say “roll the dough to 20 cm wide” I need to translate that to inches because my brain doesn’t work in centimeters. Never has, probably never will.
DIY and craft projects – Sewing patterns from Europe. Woodworking plans from Canada. Knitting instructions from Japan. They’re all metric. You’re gonna need to convert constantly if you do any kind of crafting.
Tech specs – Monitors, tablets, laptop dimensions. Sometimes they’re listed in centimeters, especially from non-US manufacturers who default to metric.
Travel – Reading signs in other countries. Understanding luggage restrictions. Dealing with rental car dimensions. Pretty much everything outside the US uses metric exclusively.
Kids’ homework – My daughter’s in 4th grade and they’re teaching both systems now. She comes home with questions about converting between them and I need to actually know the answer, not just Google it every time.
The “Close Enough” Method for Quick Estimates
You’re at Target. You’re looking at a shelf organizer. The box says 20 cm but all the dimensions in your head are inches. Your phone’s dead. What do you do?
Here’s my cheat code: Divide by 2.5 instead of 2.54
I know it’s not exact, but it’s way easier to do in your head and gets you close enough for government work.
20 ÷ 2.5 = 8 inches
The real answer is 7.87 inches. So you’re only off by 0.13 inches, which is basically nothing for everyday decisions. Nobody’s gonna notice that difference when you’re eyeballing a decorative item.
Another mental trick that works just as well: Multiply by 0.4
20 × 0.4 = 8 inches
Same result, just a different path to get there. Use whichever one feels more natural to your brain. I tend to use division because that’s how I learned it, but my brother prefers multiplication. Whatever works.
These shortcuts have literally saved my bacon when I’m standing in a store trying to figure out if something fits in my car or on my bookshelf. Can’t tell you how many times I’ve used this trick.
Common Sizes Around 20 cm (Because Context Helps)
When you’re trying to understand how many inches is 20 cm, it helps to see what else is in that ballpark:
- 15 cm = 5.9 inches (about the width of most smartphones)
- 17 cm = 6.7 inches (standard salad plate size)
- 18 cm = 7.1 inches (paperback book height for most novels)
- 19 cm = 7.5 inches (small cutting board from IKEA)
- 20 cm = 7.87 inches (dinner plate diameter, that’s your benchmark)
- 21 cm = 8.3 inches (that’s A4 paper width for reference)
- 22 cm = 8.7 inches (standard composition notebook)
- 25 cm = 9.8 inches (almost a whole foot, getting pretty big now)
What’s crazy is how fast the size jumps as you go up. The difference between 20 cm and 25 cm doesn’t sound like much when you’re reading it, but that’s 2 inches. That can be the difference between something fitting perfectly and not fitting at all. I’ve learned this lesson the hard way multiple times.
Don’t Make These Mistakes (I’ve Made Them All)
Mistake #1: Multiplying when you should divide
This is the biggest one and I still catch myself doing it sometimes. Your brain sees “20 cm to inches” and thinks “oh, I need to use 2.54” and then multiplies 20 × 2.54 = 50.8 inches.
That’s over 4 feet long. Obviously wrong for most things you’re measuring, but I’ve done it when I wasn’t paying attention and was just going through the motions.
The trick is to remember: centimeters are SMALLER than inches. So when converting cm to inches, the number should get SMALLER. That means divide, not multiply.
Mistake #2: Using 2.5 for precise measurements
The 2.5 shortcut is fantastic for ballpark estimates and quick mental math. But if you’re ordering custom curtains, cutting materials for a project, or doing anything where precision matters? Use 2.54. Don’t be lazy like I was.
I learned this the hard way when I was building floating shelves last year. Used 2.5 for my conversions because I was too lazy to grab my calculator. The shelves ended up slightly off and I had to recut everything. Wasted a Saturday and about $40 in materials.
Mistake #3: Forgetting which number you wrote down
You do the conversion, scribble “7.87” on a piece of paper, get distracted by your phone for literally two minutes, come back and think “wait, was that inches or centimeters?”
Always label your units. Always. Write “7.87 in” or “20 cm” so future-you doesn’t have to guess or redo the calculation. This is basic stuff but it’s easy to forget when you’re in a hurry.
Mistake #4: Trusting your intuition
Your gut is terrible at metric conversions unless you’ve grown up using both systems side by side. I still catch myself thinking “20 centimeters sounds small” when it’s actually pretty substantial – almost 8 inches!
Don’t guess. Just don’t. Do the math. Takes 5 seconds with a calculator and prevents expensive mistakes. I can’t count how many times I’ve almost ordered the wrong size thing because I trusted my gut instead of doing the conversion.
Tools That Make This Stupid Simple
Look, mental math is great and all, but sometimes I just want the answer without thinking about it.
Google is your best friend – Type “20 cm to inches” in the search bar. Answer pops up instantly in a box at the top. You don’t even need to click on anything. Google’s unit converter handles this perfectly.
Phone calculators – Most smartphones have a unit converter built into the calculator app now. On iPhone, you flip it to landscape mode and there’s a converter option. Android has something similar depending on which phone you’ve got.
Voice assistants – “Hey Google, how many inches is 20 cm?” Works perfectly every single time. Same with Alexa or Siri. Sometimes I use this when my hands are dirty from a project and I can’t touch my phone.
Dedicated apps – There are probably 50 different unit converter apps in the app stores. I’ve got one called “Unit Converter” (real creative name, right?) that’s free and works offline. Handy for when I’m in a store with bad signal, which happens more often than you’d think.
But even with all these tools, I still think it’s worth learning the manual conversion. Batteries die at the worst possible times. Apps crash. Sometimes you need to know this stuff and technology isn’t available. Plus it just feels good to be able to do it in your head.
The Weird History Nobody Asked For (But Is Kinda Interesting)
Ever wonder why we’re stuck with two completely different measurement systems in the first place?
Blame the French Revolution. No joke.
Before the metric system, every region had different measurements. A “foot” in Paris wasn’t the same as a “foot” in London. Total chaos for trade and science. Imagine trying to do international business when nobody agrees on basic measurements.
So in the 1790s, France said “enough of this nonsense” and created the metric system. Everything based on powers of 10. Clean, logical, scientific. The history of the metric system is actually pretty fascinating if you’re into that sort of thing.
The meter was defined as one ten-millionth of the distance from the equator to the North Pole. A centimeter is just one-hundredth of a meter.
Meanwhile, inches came from medieval England where measurements were based on actual body parts. An inch was literally three barleycorns laid end-to-end. Not exactly precise, you know? Smithsonian Magazine has some great articles about the history of measurement if you want to dive deeper.
The weird part? The US almost went metric in the 1970s. There was a whole government program. They were printing metric road signs and everything. My dad remembers seeing them as a kid.
Then it just… fizzled out. People didn’t want to change. So now we’re one of only three countries (along with Liberia and Myanmar) that hasn’t officially adopted the metric system. You can read more about why America didn’t go metric on NPR’s archives.
Which is why you’re here asking how many inches is 20 cm instead of just knowing it instinctively like people in literally every other developed country.
Teaching Kids This Conversion
My daughter asked me about this last week for her math homework. Here’s what actually worked and what didn’t.
I grabbed a ruler that had both inches and centimeters on it – if you don’t have one, get one, they’re like $2 at Target. We measured random stuff around the house. Her toy car, a book, a hairbrush, her water bottle. Wrote down both measurements every time.
Then I showed her: “See where 20 cm is on this side? Now look at the inches on the other side. It’s almost at 8, right? That’s how they relate.”
Physical objects beat abstract numbers every single time with kids. Once she measured 10 or 15 things, she started getting an intuitive feel for the relationship between the systems. Now when I ask her “about how many inches is 20 cm?” she says “like 8” without even thinking about it.
We also made it a game. I’d show her something and say “this looks like 20 cm, right?” and she’d measure it. Sometimes she was close, sometimes way off, but the point was she was developing that visual sense. That’s more valuable than memorizing formulas.
Professional Stuff (If You’re Into That)
Different jobs care way more about accurate conversions than others. Some professions, you can be ballpark. Others? You need to be exact.
Construction and carpentry – You’re working from blueprints that might be in metric, or using materials manufactured overseas. Get the conversion wrong and nothing fits together properly. Fine Homebuilding has tons of articles about working with both measurement systems.
Healthcare – Medical equipment often uses metric measurements, but patient records might be imperial depending on where you are. Converting wrong could legitimately harm someone. The CDC emphasizes the importance of accurate measurements in healthcare settings.
Fashion and tailoring – Working with patterns from Europe or fabrics from Asia means constant conversions. The difference between 20 cm and 21 cm could be the difference between a garment fitting or not. One centimeter can make or break a design.
Engineering – When you’re designing parts that need to match up precisely, or collaborating with international teams, both measurement systems are unavoidable. MIT OpenCourseWare has engineering courses that cover unit conversions extensively.
My brother’s a machinist and he says he converts between inches and millimeters (not centimeters, but same basic idea) probably 50 times a day. It’s just part of the job. He doesn’t even think about it anymore, it’s second nature.
The Rounding Question
How exact do you need to be when figuring how many inches is 20 cm?
Depends entirely on what you’re using it for. Context matters here.
For shopping: 8 inches is totally fine
If you’re eyeballing whether a decorative bowl fits on your shelf, rounding to the nearest whole number is perfectly adequate. 8 inches vs 7.87 inches isn’t gonna make or break anything. You’ve got wiggle room.
For projects: Use 7.87 inches
Making something with your hands – woodworking, sewing, crafting – keep at least two decimal places. Those little fractions add up, especially when you’re making multiple cuts or seams. Popular Mechanics often discusses precision in DIY projects.
For technical work: Keep more decimals
Engineering, scientific applications, anything where tolerances are tight – use 7.874 or even more decimal places. Precision matters. The National Institute of Standards and Technology provides detailed guidelines on measurement precision.
My Personal Conversion Cheat Sheet
I’ve got these memorized because I use them constantly. Worth memorizing if you do any kind of international shopping or crafting:
- 5 cm = 2 inches (small item, USB drive size)
- 10 cm = 4 inches (phone width, roughly)
- 15 cm = 6 inches (standard ruler, half foot)
- 20 cm = 8 inches (I round up for easier math in my head)
- 25 cm = 10 inches (getting bigger now)
- 30 cm = 12 inches (that’s exactly one foot, easy to remember)
Knowing these benchmarks means I can estimate anything in between without pulling out a calculator. Something’s 22 cm? Well, that’s a little more than 20, so a bit over 8 inches. Easy enough. Not exact, but close enough for most situations.
When 20 cm Actually Isn’t 20 cm
Here’s something annoying I’ve learned from experience: product listings lie. Well, not intentionally lie, but they’re not always accurate.
Not intentionally, usually. But manufacturers round measurements all the time. They measure inconsistently depending on who’s doing the measuring. Sometimes they list one dimension when you actually need a different one – like they measure width but you need depth.
That “20 cm wide” basket might actually be 19.3 cm or 20.8 cm depending on where they measured and how generous they were feeling that day. Or whether they measured the inside or outside dimensions.
So even after you convert and know how many inches is 20 cm, remember that’s the theoretical answer. The actual product might vary by a bit. This is especially true with cheaper products from overseas sellers.
Always read reviews. Look for photos where people show the item next to familiar objects – a soda can, a ruler, their hand. Those give you way more context than the official measurements ever will. And when in doubt, message the seller and ask for exact measurements. Most will respond within 24 hours.
The Bottom Line
How many inches is 20 cm?
7.87 inches is the precise answer. That’s what you get when you divide 20 by 2.54.
Round to 7.9 for most everyday purposes. Round to 8 if you’re just estimating and don’t need precision.
The formula’s straightforward enough: centimeters ÷ 2.54 = inches. Going backwards, inches × 2.54 = centimeters.
But honestly? This whole conversion thing isn’t really about memorizing formulas or doing math. It’s about taking measurements from a system you don’t use and translating them into something that makes sense in your world. It’s about not getting surprised when your “small” decorative item shows up and it’s actually pretty big.
I’ve probably looked up “how many inches is 20 cm” at least a dozen times in my life before it finally stuck in my brain. Ordering furniture online, following recipes from British cooking shows, helping with homework, measuring for home projects. Each time, taking those 5 seconds to convert saved me from making a dumb and expensive mistake.
Keep that 2.54 number handy. Keep a calculator within reach. And next time someone asks you how many inches is 20 cm, you can confidently tell them it’s just shy of 8 inches – and actually understand what that looks like in real life.
Now go convert stuff with confidence. And maybe actually measure that thing before ordering it instead of guessing like I always do. Learn from my mistakes.