How to Read a Tape Measure Properly

The loose hook is not a fault, and that trips up nearly everybody

The question I get asked about tape measures more than any other is whether the wobbly bit on the end means the tape is broken, and it doesn't, it's the single cleverest thing about the tool. The hook slides by exactly its own thickness, so when you push it against something it moves in by that much, and when you pull it over an edge it moves out by that much, and either way the reading is right. Hold the hook still and you're out by about a millimetre every time, which is nothing on a fence and quite a lot on a cabinet door.

Reading the markings

On a metric tape it's simpler than it looks.

• The big numbers are centimetres, and the bolder ones every ten are metres.
• The small lines between them are millimetres, ten to a centimetre, and the slightly longer line in the middle is the half centimetre so you can count quickly rather than one at a time.
• The red marks are stud centres. On an Australian tape they usually fall at 450mm and 600mm, which are the two standard spacings here, so you can mark out a whole wall without doing any arithmetic.
• A dual tape has imperial on one edge and metric on the other. Pick one and stay on it for a whole job, because mixing them mid job is how a measurement ends up 25mm out.

Some tapes also carry black diamonds, which come from American timber framing and mark a five joist layout. They are not much use on an Australian job and you can ignore them.

Five things that make a measurement right

• Let the hook do its job. Push it for an inside measurement, pull it for an outside one, and don't pinch it.
• Keep the tape flat and taut. A tape that sags across a long span reads long, and a tape running over a skirting instead of along the wall reads long too.
• Read square on. Looking at the blade from an angle shifts the mark, which matters at the millimetre level.
• Use the lock, then mark. A pencil line with a V on it pointing at the exact spot beats a dash, because a dash is 2mm wide and you'll cut to the middle of it.
• Measure the same way twice. Measure twice cut once only works if both measurements are taken the same way, from the same end.

Inside measurements, the bit nobody uses

Measuring a doorway or a cupboard by bending the tape into the corner is always a bit of a guess. The length of the case is printed on the case for exactly this reason, usually somewhere around 75mm. Butt the case against one side, read where the blade leaves it at the other, and add the two. It's accurate and it takes about three seconds.

Two things that actually go wrong with a tape

Tapes do not stretch, whatever you read. What happens is that the hook gets bent, usually from letting the blade snap back at full speed, and once the hook is out of square every measurement you take is wrong by the same amount in the same direction, which is the worst kind of wrong because it looks consistent.

The other one is a kinked blade. A tape that has been stood on has a crease in it that stops it standing out straight, so you lose the reach that makes a long tape useful. Ease it back in rather than letting it fly, and it'll outlast several that get treated properly for a fortnight and then forgotten.

Check it occasionally against a steel rule. If the first 100mm doesn't line up, bend the hook back or replace the tape, because a wrong tape is worse than no tape.

Shop related products

• Supercraft Hi-Vis Tape Measure, 8m. The everyday one, and easy to find on a job.
• Supercraft Long Tape Measure, 50m. For fence runs and paddock work where an 8m is hopeless.
• Supercraft Stainless Steel Rule, 300mm. What you check the tape against.
• Supercraft Chalk Line Reel, 30m. Turns two marks into a straight line across a whole wall.
• Supercraft Carpenter's Pencil, Hard. A fine line rather than a fat one.

Did you know we also keep the Kincrome Xtenda 8m, the Kincrome 10m and a dual metric and imperial 8m on the shelf in store. Those aren't listed on the website, so give us a ring on (08) 8536 4333 to check what's there.

Where to get it sorted

If you're measuring up for timber, bring the numbers in and we'll cut it to length on the saw bench while you wait, which saves you doing the maths twice. Have a look at our essential services.

Keep reading

• How to Choose the Right Anchors and Screws for Mounting Heavy Items
• How to Deep Clean Your Home Without Damaging Surfaces
• How to Maintain Your Roof and Gutters to Prevent Leaks

I still mark with a V and I still measure from the same end twice, because I'm the person those two habits were invented for.

Cheers,

Candeece

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