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Measuring Tools

Whether it's length, distance, or angle, when the measurement you take is critical, so is the tool—and so is your technique

Tools That Measure Up

Photo by Francesco Mosto

As a woodworker, I'm obsessed with accuracy in measurements. I once froze a 25-foot steel tape measure and baked another one, to see if they'd still read the same. They came within a sixteenth of an inch of each other before and after, and it didn't seem to matter that I'd shelled out $20 for one and a mere $5.95 for the other.

The lesson here is whether it's lengths, distances, diameters, or angles, you can trust modern measuring tools. The cause of mismeasurement is the person who's measuring—you have to choose the right tool for the task and know how to use it correctly.

On the following pages, you'll find what you need for basic household measuring, plus a few specialized tools for extra-big and super-small jobs. If, like me, you worry about the veracity of your measurements, you can opt for electronic tools, which minimize human error. Even This Old House general contractor Tom Silva, a digital skeptic from way back, has been won over—sort of—by his sonic measuring tool. "I'm always surprised by how accurate it is," he says. "I check it with a tape every time."

Dial Caliper (for small distances)

Photo by Francesco Mosto

Best for: Measuring outside and inside diameters of pipes, screws, and drill bits.

Look for: 6-inch caliper, which can handle most household needs; dial readout that gives measurement in sixty-fourths or hundredths of an inch (metric models also available).

Shown: 6-inch dial caliper, from General Tools; about $44; generaltools.com

Folding Rule (for small distances)

Photo by Francesco Mosto

Best for: Measurements inside door and window frames, bookcases, cabinets, and other built-ins.

Look for: 6-inch metal slide, the most reliable way to get an accurate inside measure. After you've unfolded as many segments of the rule as you can, extend the slide and add on its measurement.

Shown: Folding 6-foot rule with slide, from Lufkin; about $16; amazon.com

Metal Rule (for small distances)

Photo by Francesco Mosto

Best for: Measuring and cutting roll and sheet materials, such as wallpaper, glass, and plastic.

Look for: Rigid, thick metal rule, which makes a great straightedge when cutting materials; metric and English measurements.

Shown: 36-inch heavy-duty aluminum straightedge, from Empire Level; about $6; acmetools.com

Digital Tape Measure (for small distances)

Photo by Francesco Mosto

Best for: General measuring without the hassle of reading fractions.

Look for: Tape that can convert fractions to decimals and compensates for the size of the tape case on an inside measure.

Shown: Starrett electronic digitape; about $86; sears.com

Tape Measure (for small distances)

Photo by Francesco Mosto

Best for: General measuring.

Look for: 25-foot or longer tape that's at least 1 inch wide so it can extend without bending, and/or a narrow 10-foot tape, which fits easily in a pocket; fractions and feet clearly marked; 16-inch intervals (stud centers) noted in color or bold type.

Shown: Stanley FatMax 25-foot tape measure; about $20; stanleytools.com

Rafter Square (for angles)

Photo by Francesco Mosto

Best for: Measuring angles on rafter pitches, stair slopes, and miters.

Look for: Aluminum square; markings for angles as well as roof pitch (expressed in whole numbers 1 to 12).

Shown: 12-inch Speed Square with layout bar and stop bolts (not shown), from Swanson Tool Co.; about $19; sears.com

Electronic Protractor (for angles)

Photo by Francesco Mosto

Best for: Measuring and copying angles.

Look for: Adjustable tool that can determine an angle to 0.1 degree; digital readout; calculator that can figure miter-saw settings for crown molding.

Shown: Miterfinder digital protractor from Bosch Tools; about $155; acetoolonline.com

Sonic Measure (for long distances)

Photo by Francesco Mosto

Best for: Measuring rooms and interior spaces up to 50 feet across.

Look for: Laser pointer so you can see exactly where you're measuring; accuracy to 1 percent or better.

Shown: Zircon ultrasonic measure; about $40; amazon.com

100-Foot Tape Measure (for long distances)

Photo by Francesco Mosto

Best for: Measuring long distances, as in foundations, house exteriors, and garden plots.

Look for: Durable fiberglass or steel tape.

Shown: Stanley FatMax 100-foot tape rule; about $20; sears.com

Walking Wheel (for long distances)

Photo by Francesco Mosto

Best for: Long exterior measurements, such as lot boundaries or driveway layout.

Look for: Large wheel (12-inch diameter or more); odometer-style or electronic counter that goes up to 10,000 feet and subtracts when wheeled backward; kickstand.

Shown: Roadrunner professional long-distance measuring wheel, from Keson; about $56; homedepot.com