Introduction: How to Measure Things Without a Ruler

Picture of How to Measure Things Without a Ruler

Some of us don't always carry a tape measure/ ruler/ caliper with us all the time, and are at a loss when we need to measure something. In this instructable, I'll help you solve this predicament by effectively measuring things you usually, if not always have within arms reach: credit cards, dollar bills, coins and cell phones. This way, when you need to measure something (and don't have a ruler handy) you can use your standardized objects to measure against.

Let's get started!

Step 1: Whats in Your Pockets?

Picture of Whats in Your Pockets?

Look into all your pockets right now, likes are you probably have some crumpled dollar bills, a credit card (or business card) some loose change, and your cell phone. We are going to measure these articles and use those measurements to serve as makeshift rulers.

Step 2: Measuring Up

Picture of Measuring Up

A typical credit card measures about a bit under 3.5 inches wide by 2 inches long.

A U.S bill note measures 6 inches wide by 2.5 inches long

A U.S quarter dollar (new or old) measures about 1 inch in diameter

An Iphone 5S measures 2.3 inches wide and 4.9 inches long

Step 3: Dollar Measures Up

Picture of Dollar Measures Up

I found that after measuring the dollar bill was probably the best makeshift ruler, as it is a 1/2 foot, and because it is foldable, I could easily figure out any fraction almost exactly.


Willy Keith (author)2016-06-16

I'm insulted by the idea of being illiterate. Everybody Knows! Everyone who has been educated and attended school and graduated. To Identify One Inch: First, you will take a perfect circle and make a center in it. Or use a compass rose and draw a circle. The bigger the circle the more accurate the one inch will be. However, when using the compass rose circle, no matter how big the circle is; one inch will always equal one inch! I'm not going to reveal the buisiness secrets to the compass rose, which in mapping is used to mark one inch to begin with. It's just a big picture of reading I don't want to do, or use when I want the answers now, without uelling ad screaming and acting like a mad scientist! Good Day, and Bidd Well!

EmilyS69 (author)Willy Keith2017-10-16

Sure. Where in my house will I find my compass rose? Seeing as I don't have one.. I guess I'll just use a dollar bill. -_-

silverrenshp (author)Willy Keith2016-09-26

I'm not sure how this insinuates you are illiterate... but if you were not in-need of quick, on-hand methods to find an object's size, perhaps it's not an instructable for you?

Petepete40 (author)2017-08-14

Just wanted to messure my pnut dont no if its doing the job:(

DarkG4 (author)2017-07-08

That poor 20 dollar bill.

young_savage15 (author)2016-04-09

do they have it in cm not in.

zacker (author)2015-01-12

I like the US bill thing... I think im gonna mark one out at 1/2" intervals and fold it up and just keep it in my wallet or folded up flat in between my phone and its case! thanks!

zacker (author)2015-01-12

I got one of those Swiss Army Knife credit card sized gizmos with me all the time, its about the size of a credit card it has a small folding scissors, a small knife, a tooth pick, tweezers, a nail file with a slotted screwdriver end, its also got a inch scale ruler printed on its long edge and its about as thick as two or three cards stacked on top of each other. I used to have a different one from another maker that had a 6" tape measure in one end.

dave367 (author)2014-07-17

A few others if you like: For an average man (5'10") or woman (5'4"), one meter is very near the distance of your navel above the ground while standing barefoot (women are shorter than men, but have longer legs, so the navel is surprisingly stable). 150 centimeters is 5', or the distance from the ground to your mouth if male, to your eyes if female. An average man is 180 cm tall, and weighs the same, in pounds. An average woman weighs 125 lbs, so average humans, in groups, weigh close to 150 lbs. each. A heavily dressed man--with overcoat and gumboots, weighs 200 lbs. Ditto a normally dressed man, soaking wet. (in the US, add 10% to these numbers. Sorry)

One cubit = 500 millimeters. Thus 300 cubits = 150 meters. Big boat. 30 meters = 100 ft. 30 centimeters = one foot (1.5% error).

An American bill, whether one dollar or 100 dollars, weighs precisely 1 gram. As they wear they become dirty, maintaining almost precisely their initial weight (dope dealers count large amounts of cash by weighing it). A nickel weighs 5 grams. One dollar's worth of nickels weigh 100g, roughly one-quarer pound.

A pint of water weighs a pound ("A pint's a pound the world around") 4% error.

An average man, at a brisk marching pace, will have a stride very close to 32 inches (the Roman mile is derived from this = 1000 double paces = 5280 ft). A bit more relaxed pace and most can figure 30" exactly.

An American football field, minus the end zones, is near an acre. Two American football fields side-by-side, now *including* the end zones = one hectare.

All the above are slightly inaccurate, but are easy to measure, remember and intuit.

harvey544 (author)dave3672014-12-12

A pint of water weighs pound and a quarter,

dave367 (author)harvey5442014-12-12

An imperial pint may weigh 1.25 lbs. An American pint weighs 1.04375 lbs, at STD. Splitting hairs you may feel, but as Great Britain has gone metric (except for beer!), neither pints nor pounds are "official" there anymore, leaving the great preponderance of the pint unit to be in America, each weighing one pound. ;-)

FWIW, the very definition of "fluid ounce" is that volume of water which weighs one ounce. 16 fluid ounces = 1 pint and 16 oz = 1 pound. It was all so simple back in the olden days

amclaussen (author)2014-07-22

Here in Mexico, we use the lenght between the fingers of a hand (forefinger and thumb) with one arm extended, to the figers of the other hand (you just have to stand like an Archer ready to throw an arrow, but instead of holding an arch, you hold tight the end of a rope, electric zip cord etc. and extend only one arm. The distance from the extended hand-arm to the other hand placed against your shoulder is almost exactly one meter! In that way you can very quickly measure a lenght of rope, cable etc. With a Little practice and checking, you can learn how to be precise to less than 1% error most times. Amclaussen.

(sorry for my English description, English is not my native language).

KROKKENOSTER (author)2014-07-20

Supersimple to do why have I not think about this.

Light_Lab (author)2014-07-19

I carry around in my pocket a tiny tool set including a tape measure, slide caliper, fold up scissors etc Been so useful over the years I wouldn't go anywhere without it.

HollyMann (author)2014-07-18

Very interesting :) and good information to know. :) Love it!

Ricardo Furioso (author)2014-07-17

Also makes sense to measure your thumb to pinkie spread, the length of your shoe, and your arms tip to tip as far as you can spread them.

Thank you for the helpful instruct able. Please make more.

amalkhan (author)Ricardo Furioso2014-07-17

I have a bunch. Check 'em out!

mclancer (author)2014-07-17

I have this small tape measure that hangs on to my key chain. I can measure anything up to 36" (yes, we in Canada still prefer the imperial system).

msimes (author)2014-07-16

I added measurements on the inside of all of my belts and my wallet so all I need to do is take off my belt and I have an instant yard stick for smaller items my wallet works great

ElectroFrank (author)msimes2014-07-17

Excellent. But (depending on what your waistline is doing) I think
you will find that leather belts stretch over their lifetime, so it may
be useful to check the linear precision of your calibration at regular

And I have this thought . . . isn't it difficult trying to measure things when you're already having to use one hand to stop your trousers falling down ? ;-)

alcurb (author)2014-07-17

This is awesome and It had never occurred to me to fold up a bill into 6 equal parts. Ingenious. This is particularly useful when you need to show scale in a photograph of an object larger than a quarter.

The Best Hobbies Blog (author)2014-07-16

By the way I shared your instructable on the "EveryManShouldKnow" reddit page and it's currently doing very well. Here's the url if you're interested in seeing what people have to say about it.

thanks for sharing the love!

er13k (author)2014-07-17

Something that we always have in our pockets it's our smartphone, I use this application for years to measure small things:

For bigger things I use my hand, knowing the measure of it.

enginepaul (author)2014-07-17

A standard business card is 3 1/2 by 2 inches.

Most bond paper is in the .0045 to .005 inches range, many business cards are .010"

Passing You (author)2014-07-17

There is also a sheet of paper 11 inches x 8.5 inches

billbillt (author)2014-07-17

double plus good.....

kenyer (author)2014-07-16

Maybe a crazy idea and I could be totally wrong, but could your foot be 1 foot long? We often use steps to measure meters. One big step is close to 1 meter and I know for myself that I use close to 11 normal steps for 10 meters.

BobGarrish (author)kenyer2014-07-17

My actual foot is shorter than a foot, and I suspect most peoples are (I have size 10.5/12.5 feet), but my shoes are exactly a foot long. I can pace something 20+ feet long toe to toe with them, pull out a ruler and measure the remainder, and be within a half inch of a measuring tape.

I'm never getting new shoes :)

The Rambler (author)kenyer2014-07-16

This does work as a very general measurement... assuming you're a man with an average foot size... or a woman with slightly larger than average foot size. For instance I know the shoes I'm wearing right now are 12.5", so roughly a foot. Sans shoe my foot is probably about an inch or so shorter.

The Rambler (author)2014-07-16

The dollar bill trick is incredibly useful. So far I've been going with the fact that I know pinky tip to thumb tip is 9" for me but that dollar measurement is a lot more precise and easy to measure with.

Tarun Upadhyaya (author)2014-07-16

Thats a very useful information :). Thank you so much for sharing.

kenyer (author)2014-07-16

Here in the old country's, I always use a piece of A4-size paper. I know by hart that it is 21 x 29,7 cm and there is always some paper nearby. So 3 x the length and half a width is 1 meter. (we don't have dollars and all our euro's have a different size)

A friend of mine learned all his body measurements. So he knows how long his fingers are, and the distance from his finger to his thumb. The size of his arm, finger to elbow, leg, arms wide and so on. (I tried thad, but never seem to remember those measurements) It is really handy when this friend is nearby.

megustacantar (author)2014-07-15

Great idea, Amalkhan. MacGyver would be proud.

twitting (author)2014-07-15

Thanks! The dollar bill trick is awesome.

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