Parts of a Tape Measure – Labeled Diagram, Inside and Out

All 8 parts on the diagram

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Outside 7

Case It holds the coiled blade and the spring.
Blade (tape) The strip you measure with. It rolls up into the case.
Hook It catches on an edge so one person can measure.
Lock (blade lock) It holds the blade out at any length.
Graduations (markings) The lines a length is read from.
Rivets They hold the hook on the blade.
Stud mark Marks the usual spacing of wall studs: every 16 inches.

Inside the case 1

Spring It pulls the blade back into the case.

How this list was compiled: Every name checked on 2026-09-30 and kept only where at least two of these use it. (1) Wikipedia, Tape measure, https://en.wikipedia.org/wiki/Tape_measure : case, hook on the end held by loose rivets through oval holes, tape lock, spring return, markings, the special marks every 16 inches for studs. (2) US Navy, Tools and Their Uses, Rate Training Manual (ERIC ED132362), full text at https://archive.org/details/ERIC_ED132362 : steel tape, case, hook, graduations. (3) US Army, TM 9-243, Use and Care of Hand Tools and Measuring Tools, full text at https://archive.org/details/use-and-care-of-hand-tools-and-measuring-tools-1983 : steel tapes, the hook at one end. (4) How To Use a Tape Rule, a high school shop lesson plan (Western Curriculum Coordination Center, University of Hawaii; ERIC ED283549), full text at https://archive.org/details/micro_IA41153422_0178 : the parts of the tape rule are the case, the blade and the hook. (5) and (6) two makers' catalogs, names only, full texts at https://archive.org/details/lufkin-catalog-106-1967 (case, blade, end hook riveted on, lock, graduations, spring return, 16-inch centers marked) and https://archive.org/details/stanley-hand-tools-catalog-34-1969 (case, blade, blade lock, hook, graduations, stud marking, belt clip). (7) US Patent 2,599,320, Measuring tape and case therefor, full text at https://archive.org/details/us_patent_2599320 : case, hook, the coil spring inside the drum that reels the tape in. Licence: own work

The drawing: Own drawing from plain geometry; nothing traced. Licence: own work

How it works

A tape measure is a long, flexible ruler that rolls up into a case. The drawing shows one with its blade pulled out, and a window cut in the case to show what is inside.

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The parts you can see

The blade carries the graduations. At its end a hook, held on by rivets, catches on the edge of the thing being measured. The lock on the case holds the blade out at any length.

The internal parts of a tape measure

Inside the case the blade is wound into a coil. A spring coiled in the middle of it pulls the blade back into the case when the lock is let go.

Questions and answers

What are the parts of a tape measure called?

The case, the blade (the tape itself), the hook on its end with its rivets, the lock, and the graduations printed on the blade. Inside the case is the spring that pulls the blade back in.

Why does the hook on a tape measure move?

The hook is held by loose rivets through oval holes, so it can slide a distance equal to its own thickness. Hooked over an edge or pushed against a wall, the measurement comes out right either way.

What are the stud marks on a tape measure?

Many US tapes carry a special mark every 16 inches. That is a standard spacing for the studs in a wall, so the marks show where each stud goes.

Why is the blade of a tape measure curved?

A carpenter's tape is a curved ribbon of metal. The curve keeps the blade stiff and straight when it is pulled out, and it can still roll into a coil inside the case.