How to Estimate Measurements Without a Ruler or Tape Measure

how to measure without a ruler

Illustration: © The Spruce, 2018

When you don't have ruler or tape measure on hand, there are many easy ways to estimate measurements using parts of your body or items you may have on hand. This can come very handy when you are shopping to determine if an item is the proper size. Nothing is more frustrating than buying something—wallpaper or fabric with a certain pattern size, for example—only to get home and find that it's just a bit too large or too small. This can be particularly helpful for scale model enthusiasts, such as model railroaders or dollhouse collectors, who are always on the lookout for interesting accessories for their hobbies. 

If you learn the lengths of some common body parts and ordinary objects, you can use these as units of measurement to come up very close estimates of the measurements of items.

Common Measurements Based on Your Body

Parts of your body can be used to estimate many common units of measurement. Obviously, people vary in size, so it's best to first measure your own body parts in order to understand how close your own proportions are to these averages. 

  • 1 inch (2.5 cm) is roughly the measurement from the top knuckle on your thumb to your thumb tip. Measure yours to see how close it is to 1 inch. After all, you should always have a thumb handy for a guide for measuring items under 6 inches (15cm)! In model miniatures, such as standard dollhouse scale (1:12), 1 inch is equal to roughly 1 foot. This is also quite close to the size used for standard 28mm gaming figures for wargaming. One inch is also close to the height of human figures in 1:64 or "S" scale model railways, where the 28mm size is a "heroic" figure, while the "normal" figure is roughly 1 inch or 25mm tall.
  • 4 inches (10cm), or one hand width for measuring horses, is roughly the width of most people's hands measured across your bottom knuckles (without the thumb).
  • 1 yard (36 inches or 92cm) is roughly the distance from your nose to the first knuckle (the fist knuckle) of your fingers on an outstretched arm. If you use this measurement often, measure your arm to see how close this measurement is to one yard.
  • 1 meter (39 inches) is a similar measurement to the yard above, but use your arm with fingers extended and measure to the tip of the fingers. This is an easy way to estimate yards and meters of cord, fabric or ribbon. Check the length of your arm against a ruler or measuring tape to find out how close to 1 meter this distance is for you. 
  • One elbow length. The distance from your bent elbow to the tips of your fingers is 15 to 18 inches (35 to 48 cm) for most people.
  • Measure with your foot. A woman's size-9 foot (US and Canada) is usually 10 inches (25 cm) long. In Europe, this is a size 40 and in the UK, size 6.5.

Measurements Based on Office Items

Ordinary items you have around your office or home desk have standard measurements that can be used to estimate the measurements of other items. ​

  • A standard business card is 3.5 inches long x 2 inches high (9 x 5 cm).
  • Standard credit and ID cards are 3.375 inches high x 2.125 inches long. ( 8.5 x 5.4 cm).
  • A standard sheet of typewriter paper, as most people know, is 8.5  x 11 inches in size.
  • Business envelopes are 4 inches x 9.5 inches.
  • A standard paper clip is 1.25 inches long; a giant clip, 1.875 inches. 

Use Coins and Bills to Measure

Almost everyone carries a few bills or coins in their pocket, and knowing their dimensions can help you estimate measurements of other items.

  • A US bill is 2.5833 inches tall x 6.166 inches long (6.5cm x 15.5 cm).
  • Canadian bills are 6 inches long x 2.75 inches tall (15.2 x 7cm).
  • A 1-cent coin is .75 of an inch (2 cm) across.
  • A quarter is just under 1 inch (2.5 cm) across.

Standard Furniture Measurements

You can use these standard dimensions as the basis for estimating the rough size of larger items. And by converting the measurements, you can also use them when buying pieces of furniture or accessories for model buildings or dollhouses. The sizes below are the sizes of the real items: in 1:12 scale, for example, a six-foot (72-inch) door would be 6 inches tall (15 cm).

  • Standard modern doors are 78  to 80 inches (198 to 203 cm) tall.
  • A dining room tabletop is usually 30 inches (76 cm) above the floor.
  • The seat of a dining room chair is usually 15 to 17 inches (38 to 43 cm) above the floor.

Your Smart Phone Is Smarter Than You Realized

Measure your cell phone and commit its dimensions to memory. Not only can the physical phone itself serve as a unit of measure, but you may also find it offers apps that provide an actual ruler scale that lets you measure small items laid on the face of the phone. For Android phones, check out an app called ON Measuring Tape. Similar apps are available for IOS phones.

Other apps are available that use the phone's camera as a viewfinder to electronically calculate measurements. For iphones models 6 and above, one such app is called Tape Measure.

Tips When Buying Accessories for Scale Models

If you regularly shop for accessories for scale models and miniatures, you should carry with you a "person" sized to the correct scale. Print out a picture of a human figure at its scale size and carry it with you to compare against any accessories you come across. 

Another trick is to keep a figure on your keychain sized to your particular scale—you can easily place it next to an object to see if it looks the correct size.