You’re trying to determine if that secondhand couch will make its way inside your doorframe, or if a shelf will fit into a odd little nook in your apartment, and naturally the one ruler you own is MIA. It happens to everyone. The good news is you don’t really need a ruler to get a decent ballpark figure. Even your hands and your wallet as well as a few things that may be on your desk right now can serve as measuring tools if you know their actual dimensions.
Here are a few ways to measure length without a ruler, all of which are fast, practical, and close enough to good for just about any everyday context.
Why Bother Learning This Skill
Most of us instinctively reach for our phone and Google “how long is X” when we need to know, but that’s not always faster or more accurate than just having a couple of benchmarks memorized. Movers, furniture buyers, DIY-ers, and even kids working on a school project: they all know there are times when you need a tape measure and there’s just nothing to be found. Once you have a handful of common reference items memorized, you can estimate distances in just a few seconds — no need to rummage through that junk drawer.
Start With Things Already in Your Pocket
Most simple gauges are usually just objects you have with you.
Dollar Bills
A U.S. dollar bill is 6.14 inches long and 2.61 inches wide, and this is true for all bills since they’re all the same size regardless of the denomination. Place a bill flat on top of whatever you are measuring, and you instantly have a 6-inch ruler. Need something shorter? Fold it in half for approximately 3 inches or double fold for 1.5 inches.
Credit and Debit Cards
Almost all of the cards you keep in your wallet—credit cards, gift cards, hotel key cards, etc.—follow the same ISO standard: 3.37 inches by 2.125 inches. That regularity makes cards a nice backup currency when you’re cashless. Line a few up edge to edge and you can cover longer stretches pretty fast.
Smartphones
Phones are more variable than cards or bills, but they mostly fall in the 5.5 to 6.5-inch -tall range. If you happen to know the exact dimensions of your phone (a little searching will turn them up), it becomes one of the best reference tools ever, since you’re probably holding it anyhow.
Use Your Own Body as a Backup Ruler
Body-based measuring has been practiced for centuries, and is still effective because your proportions don’t fluctuate on a daily basis.
Fingers and Hands
The width of a grown man’s thumb is about an inch, which is where the phrase “rule of thumb” comes from. A hand, which when stretched out from the tip of the thumb to the tip of the pinky finger is usually somewhere between 7 and 9 inches depending on hand size.Since these figures are personal, it pays to measure your own hand once against something known (like a dollar bill) so that you have an accurate baseline moving forward. .
Forearm and Foot
The distance between your elbow and wrist is about 25 cm for most adults and one foot length (heel to toe) ranges from 22.5 cm to 30 cm. Neither is exact, but both work very well for ballpark estimates for things like boxes and furniture.
Arm Span
Here’s a neat trick: For most adults your arm span (fingertip to fingertip with your arms stretched out) is roughly equal to your height. If you’re already aware of your height, that means you know your wingspan too — which is handy for making sense of wider openings like doorframes or windows.
Walking Steps for Longer Distances
When traveling over distances longer than a room, step counting is more accurate than guessing. The average length of a human adult’s stride is around 2.5 to 3 feet. Walk heel to toe in a straight line, count your steps, then multiply by your stride length and you have a rough distance. This isn’t going to give you fudging-(or precision-)inch measurements, but it is actually useful for things like determining if a driveway can hold a trailer or a yard can hold ashed.
Household Objects With Known Sizes
Your house is full of built-in rulers, once you begin to notice them.
Paper
A US letter sheet is 8.5×11 inches and A4 (used in most of the world other than the US) is 8.27×11.69 inches. Fold a sheet in half and you get about 5.5 inches; fold it a second time for about 4.25 inches. Because of the wide availability of paper the similar thing can be said about the common printer paper which did make for a surprisingly useful backup ruler.
Coins
Coins are perfect for small the measurements and theirs sizes are regulated by the federal government, they don’t change:
- Penny: 0.75 inch (19.05 mm) diameter
- Nickel: 0.835 inch (21.21 mm) diameter
- Quarter: 0.955 inch (24.26 mm) diameter
By pressing coins tightly next to each other you can measure small distances with reasonable accuracy, which is useful for small DIY projects or seeing if a screw or bolt will fit somewhere.
CDs, Soda Cans, and Other Familiar Items
A DVD or CD is 4.7 inches in diameter. A regular soda can measures approximately 4.83 inches in height.Even a standard pencil (about 7.5 inches) is good enough for an emergency. None of these are intended to be measuring devices, but you can rely on their dimensions being consistent enough to lean on.
Build a Makeshift Ruler You Can Reuse
If you need to measure things at the drop of a hat, it’s a good idea to make a sketchy ruler you can always have on hand.
Mark a Strip of Paper or Cardboard
Use a dollar bill (6.14 inches) or credit card (3.37 inches) to mark distances you know on the strip of cardboard or cardstock. Fill the spaces with coins or your own thumb width, then label every mark. In a couple minutes you’ll have a rough but actually useful ruler.
Use String or Yarn
Cut a length of string to a known length, using a dollar bill or sheet of paper as a guide, then fold it over and over again to make smaller increments. String has one more advantage over rigid objects: it can be draped along curved surfaces and irregular objects, which a flat, rigid object simply cannot be.
Print One Out
If you have a printer, a simple “printable ruler” search will provide you with a handful of templates you can print on cardstock. Just compare the printed ruler to a known object before you use it or some printers scale the pages slightly when printing.
| Object | Approximate Length |
| Dollar bill | 6.14 inches |
| Credit card | 3.37 inches |
| Letter paper (short side) | 8.5 inches |
| Quarter | 0.955 inches |
| Nickel | 0.835 inches |
| Penny | 0.75 inches |
| Soda can (height) | 4.83 inches |
| CD/DVD | 4.7 inches |
| Adult thumb width | ~1 inch |
| Adult foot length | 9 to 12 inches |
| Average stride | 2.5 to 3 feet |
Quick Reference Chart
Remember these are averages. Any wear on the currency, the card issuer, and the size of your body will cause some variation, so consider these numbers as ballpark figures rather than crisp lab results.
When to Use a Smartphone App Instead
If you happen to have a LiDAR sensor on your phone or a recent camera configuration, Apple’s Measure app or Google’s Measure app can offer you a pretty close estimate through augmented reality. They are not perfect, lighting and camera angle affect them, but for a rough read on a room or a piece of furniture, they are better than guessing entirely by hand. Just don’t trust them for anything that has to be accurate down to the millimetre, like a woodworking cut.
A Few Tips for Better Accuracy
- Use fresh, crisp bills and cards as old ones may shrink slightly with age.
- Use a combination of methods when feasible; verify your calculations by using two different items to detect errors.
- For the distance, count the number of steps you take and multiply that by your step length. For longer distances, take a reading of your stride length once using a tape measure or known distance so your step count remains consistent.
- Be generous with rounding when it matters. If you’re measuring to see if something will go through a door, allow an inch or two of wiggle room because these methods aren’t precise.
Final Thought
You don’t need a full toolbox to come up with a useful measure. Between the cash in your wallet, the paper on your desk, and your own two hands, you’ve nearly always got all the information you need to make an educated, knowledgable guess.It’s not going to replace a tape measure on a real build, but for normal situations it should do.
