Measuring Guides

Short, practical guides to measuring things accurately, with or without a ruler.

• How to Read a Ruler (Inches and Centimeters)What every line on a ruler means, how to read fractions of an inch, and how to read centimeters and millimeters, with worked examples.
• How to Read a Tape MeasureInch fractions, feet and inches, the red 16-inch stud marks, the black diamonds, metric and combination tapes, why the hook is loose on purpose, and how to take inside measurements, with worked examples and a practice quiz.
• How to Measure Without a RulerEveryday objects with exact, known sizes (a dollar bill, coins, a credit card, printer paper) and how to use your phone or hand for quick estimates.
• Fraction to Decimal Inch Chart (with Millimeters)Every inch fraction from 1/64 to 1 inch as a decimal and in millimeters, plus how to convert in both directions by hand.
• How to Measure Your Ring Size at HomeThree ways to find your ring size without visiting a jeweler, plus the simple math behind US sizes and tips to avoid a ring that's too tight.
• Paper Sizes Chart (Inches and Millimeters)Exact dimensions of US and international paper sizes, photo prints, index cards, envelopes and business cards, in inches and millimeters.
• US Coin Sizes: Diameter, Thickness and WeightThe official US Mint measurements for every circulating coin, how to use a coin as a quick ruler, and how tall a roll or stack of coins is.
• How to Use a ProtractorHow to line up a protractor, which of the two scales to read, how to measure angles over 180°, and how to draw an angle of any size.
• How to Measure Your Height at HomeA step-by-step method that gets within a few millimeters of a doctor's stadiometer, how to do it alone or with a helper, and how to convert the result.
• How to Measure a TV or Monitor Screen SizeWhy screens are measured diagonally, how to measure one in a minute, the real width and height of common TV sizes, and how to check a TV will fit a space.
• How to Measure Your Foot for Shoe SizeA two-minute paper-and-wall method, a chart from foot length to US, UK and EU sizes, and how to tell whether you need a wide fit.
• How to Measure Your Wrist for a Bracelet or WatchThree ways to measure your wrist, how much to add for the fit you like, and a chart from wrist size to bracelet length. Plus bangles and watch straps.
• Picture Frame Sizes: Standard US and Metric ChartEvery standard frame size, what 'frame size' actually measures, how mats change it, and which frame sizes will crop a phone or camera photo.
• Lumber Sizes: Actual vs Nominal Dimensions ChartA 2x4 isn't 2 by 4 inches. Here are the real dimensions of every common board, stud, post and plywood sheet, and why they're smaller than their names.
• Mattress and Bed Size Chart: US Dimensions in Inches and cmThe exact width and length of every standard US mattress, how the sizes compare, how much room each bed needs, and how to measure a mattress or bed frame.
• Ring Size Chart: US, UK, EU and Japan ConversionEvery US ring size from 3 to 13 with its inside diameter and circumference, and the matching UK, European and Japanese size, in one chart.
• Necklace Length Chart: How Each Chain Length FitsWhere every standard necklace length sits, from a 14 inch choker to a 36 inch rope, the usual lengths for men, and how to find yours with a string and a ruler.
• Free Printable Ruler Worksheets with Answer KeysFour free PDF worksheets for practicing how to read a ruler: inches to the quarter, inches to the sixteenth, centimeters and millimeters, and measuring real lines. Each one has an answer key.
• Screw and Bolt Size Chart: US and MetricWhat #8 or 1/4-20 actually means, the diameter of every common US and metric screw and bolt, threads, the closest metric match, and which wrench fits.
• Drill Bit Size Chart: Inch, Metric and Tap Drill SizesEvery common fractional drill bit in decimals and millimeters, which bit to use before tapping a thread, and the right pilot and clearance holes for wood screws.
• Nail Size Chart: Penny Sizes ExplainedHow the penny system works, the length and thickness of every common nail size from 2d to 60d, and which size to use for framing, sheathing, decking and trim.
• Envelope Sizes Chart: US and InternationalThe exact size of every common envelope, what each one is made to hold, which envelope fits a letter or a greeting card, and the USPS size limits for a regular stamp.
• Business Card Size: Standard Dimensions by CountryThe standard business card size in the US and around the world, the pixel size to design at, and how bleed and safe zones work so nothing gets cut off.
• Poster Sizes Chart: US and InternationalEvery standard poster size in inches and centimeters, the pixels you need for a sharp print, which size suits which wall or event, and how far away a poster can be read.
• Hat Size Chart: How to Find Your Hat SizeHow to measure your head with a tape or a string, then match it to US, UK and European hat sizes and to S, M, L and XL. With the simple math behind US hat sizes.
• Pandora Ring Size Chart: Pandora to US and UK SizesPandora sizes its rings by the inside circumference in millimeters. Here's what each Pandora size equals in US and UK sizes, and how to measure your finger before you order.
• Cartier Ring Size Chart: Cartier to US and UK SizesCartier sizes its rings in the French system, where the size is the ring's inside circumference in millimeters. Here's how each size converts to US and UK sizes, and how to find yours.
• How to Measure for Curtains in 5 StepsMeasure the window, decide where the rod goes, then work out the curtain width and length. Step-by-step, with the numbers designers use and a calculator that does the math.
• How High to Hang Curtains (and Why Higher Looks Better)The rules designers use for curtain rod height, worked out for 8, 9 and 10 foot ceilings, with the curtain length that goes with each rod height.
• Curtain Size Chart: Standard Lengths and WidthsEvery standard ready-made curtain length and width in inches and centimeters, which length suits which room, and the curtain width and panel count for common window sizes.
• Wrench Size Chart: SAE vs Metric, Sockets and Allen KeysEvery common wrench size in inches and millimeters, which SAE and metric sizes you can swap and which will round off a nut, the wrench for each bolt, and Allen key sizes.
• Wire Gauge Chart: AWG Sizes in Inches and mmEvery American Wire Gauge size with its diameter and area, why a smaller number means a thicker wire, which gauge US home circuits use, and how to measure a wire.
• Pipe Size Chart: Nominal vs Actual SizesThe real outside and inside diameter of every common pipe size, for steel and PVC, copper and PEX, the threads that go with them, and how to identify a pipe with a tape measure or a piece of string.
• Sandpaper Grit Chart: Which Grit for Which JobWhat sandpaper grit numbers mean, which grit to use for each job from stripping paint to polishing a car, how US (CAMI) and European P grits compare, and the right order to work through them.
• Thread Pitch Chart: UNC, UNF and Metric ThreadsThreads per inch for every common US bolt in coarse, fine and extra fine, metric coarse and fine pitches, how to convert between TPI and mm, the US and metric threads that are easy to confuse, and how to measure a thread.
• Sheet Metal Gauge Chart: Thickness in Inches and mmThe real thickness of every common sheet metal gauge for steel, galvanized steel, stainless and aluminum, why 16 gauge isn't the same in every metal, and how to measure a sheet you already have.
• Extension Cord Gauge Chart: Length, Amps and AWGWhich extension cord gauge to buy for the tool and the distance, why a long thin cord makes tools run hot and slow, what common tools and appliances draw, and what the letters on a cord's jacket mean.
• Rebar Size Chart: US Bar Sizes, Diameter and WeightWhat #4 rebar means, the diameter, area and weight of every standard US bar size, their metric and Canadian equivalents, which sizes go in slabs, footings and walls, and how to identify a bar on site.
• Plywood and Drywall Thickness: Nominal vs ActualThe real thickness of 1/4, 1/2 and 3/4 inch plywood, OSB and MDF, drywall thicknesses and where each goes, standard sheet sizes, and how to measure a sheet before you buy hardware or cut a dado.
• Tap Drill Size Chart: UNC, UNF and MetricThe right drill for every common inch and metric tap, with decimal and mm sizes, the formula behind it, tap drills for NPT pipe threads, and clearance hole sizes for bolts that pass through.
• Number and Letter Drill Size ChartThe decimal and metric size of every number drill (#1 to #80) and letter drill (A to Z), the nearest fractional bit for each, how the three series fit together, and how to find the right bit for a decimal size.
• Bolt Torque Chart: SAE Grades and Metric ClassesTypical tightening torque for US grade 2, 5 and 8 bolts and metric 8.8, 10.9 and 12.9 bolts, dry and oiled, how to tell a bolt's grade from its head, and why a torque spec from the manufacturer always comes first.
• Washer Size Chart: SAE, USS and Metric WashersThe inside diameter, outside diameter and thickness of SAE, USS and metric flat washers, how SAE and USS washers differ, fender and lock washer sizes, and how to pick and measure a washer.
• How to Show the Ruler in WordView > Ruler turns it on. Plus the vertical ruler, changing inches to centimeters, what the markers do, and fixes when the ruler is missing or grayed out.
• How to Show the Ruler in Google DocsView > Show ruler turns it on or off. Plus how to set margins, indents and tab stops with it, and why the ruler can be missing.
• How to Show the Ruler in PowerPointView > Ruler in Normal view. Plus why the ruler starts at 0 in the middle of the slide, how to change units, and what to use in PowerPoint for the web.
• Is an Online Ruler Accurate? How to Calibrate ItWhy on-screen rulers show the wrong size until they are calibrated, the three ways to calibrate and how accurate each one is, device-by-device tips, and simple ways to check the result with a coin or card.
• How to Measure Inches on Your PhoneThe three ways to measure in inches with an iPhone or Android phone, which one to use for a screw or a whole room, how accurate each one really is, and how to avoid the mistakes that throw readings off.
• How Big Is 1 Inch? Everyday Objects That Are an InchWhat an inch looks like in real life, everyday objects you can use to picture 1 inch, 1/2, 1/4 and 1/8 inch, how to find an inch on a ruler, and how inches convert to centimeters and millimeters.
• How Big Is 1 cm and 1 mm? Real-Life ComparisonsWhat a centimeter and a millimeter look like in real life, everyday objects to picture each one, how to find them on a ruler, how they convert to inches, and where you'll actually run into them.
• How to Measure PD (Pupillary Distance) for GlassesA step-by-step way to measure your pupillary distance at home with a millimeter ruler, a mirror or a friend, what single, dual and near PD mean, normal PD ranges, how to check your number, and the mistakes that throw it off.
• Ear Gauge Size Chart: Gauge to mm and InchesEvery ear gauge size from 20g to 2 inches in millimeters and inches, how the gauge numbers work, how to measure a plug, tunnel or hoop, how big each stretching step is, and the mistakes that lead to buying the wrong size.
• Bra Size Chart and How to Measure for a BraHow band and cup sizes work, how to measure yourself at home with a tape, charts to convert between US, UK, EU, French and Australian sizes, a sister size table, and the fit checks that matter more than the number.