They say measure twice and cut once. Here are three ways you can measure more accurately and effectively.
Make sure you keep the tape parallel with the edge you’re measuring. Even a slight angle over a few feet can introduce a good 1/8″ to 1/4″ error.
The usual technique when making an inside measurement (a window frame, a wall from floor to ceiling) is to push the tip against one corner, and bend the tape to fit into the opposite corner. But you’ll get more accuracy this way. Say you’re measuring the width of a window from jamb to jamb. Push the tip against one jamb, and extend the tape so the case sits against the other jamb. Lock the tape, and place it directly on your stock (hooking the tip over the end and pulling), and mark your measurement at the rear of the case.
Last time, I said you might want to pick up a tape measure with inches and feet on one side and metric measurements on the other. This makes dividing a length into equal measurements a much easier calculation, and it makes it easier to measure out the result accurately. Say you’re figuring a stair run and the total height is 107 5/8″. You need to divide this by 15 to get your riser height. With a bit of fiddling (and help from a calculator), you get 7.175″. And then you have to translate that into 16ths or 32nds of an inch — I’m not even going to try. But check out the metric side. Your height is 2734 millimeters. Divide by 15 and you get 182.26 Since we’re talking millimeters — a very small increment — you can just forget about the fraction and measure out 182 mm for your riser.