How to Make Extremely Accurate Inside Measurements

The Pros’ Secret to Making Precise Inside Measurements

I get asked about woodworking measuring tips all the time. Whatever my answer is, it is always followed by the saying “measure twice, cut once.” Well, accurate measuring is very important when it comes to many DIY projects. Being off by even an eighth of an inch can mean a difference between a stable bookshelf and a wobbly one, for example. Even more important is making an accurate inside measurement. Take the same example of a bookshelf….Can you imagine if you are not accurate with your inside measurements and now your shelves are either too small (and fall), or too big (and won’t fit.) Not to mention, having an accurate measurement when woodworking translates to a more professional and finished end result. 

Checking the length of an interior dimension might sound like a straightforward task, but you’d be surprised that the more conventional ways just aren't as accurate and therefore won’t get you the flawless craftsmanship you’re looking for. An accurate inside measurement is sometimes difficult to get. Some people might bend the tape into the corner, which is a close guess at best. Or, you could run the tape measure right up against the side and add that reading to the size of the case of the tape measure. That way involves some more complex math and may end up inaccurate anyways. There is a solution that is easy, straightforward, and will give you accurate, professional results. 

In this video and blog, I’ll show you a tried and true way to make an accurate inside measurement without any complex math. If you can count to ten, it’s as easy as that! 

WHAT’S AN INSIDE MEASUREMENT 

An inside measurement is a dimension of length or height inside an object. Think bookshelves, console tables, drawers, shelves, and many other woodworking projects. Your standard measuring tape clearly shows feet, inches, and fractions of inches. Generally, the measurements on a tape measure are 16 marks to the inch. This means you can measure up to 1/16 of an inch. Other tapes measure from 32 to 64 marks to the inch. It’s essential to get to know your measuring tape so you’re familiar with it as you move around a project. 

THE TRICK?… It Is As Easy As Adding By Ten 

The trick is to measure ten inches from the end of a strip of wood. This could be any piece of wood, even scrap wood that you have in your shop. With a handy pencil draw a square line and cut the wood to exactly that length.

Just like in my video, you set the ten-inch piece of wood in place up against where you are going to measure. Then, with the end of it up against the side of the cabinet and measure from the opposite side, read the measurement, and then simply add ten inches. Isn’t that a lot easier of a math problem? 

WHY ACCURACY MATTERS

The bottom line is that your cuts are only as accurate as your marks are. This applies to all DIY projects, especially carpentry where accuracy is paramount. It is the basis for flawless craftsmanship. Whether you are working on a small or large project, all the elements of carpentry are equally important - and they truly matter. Measuring, cutting, shaping, and joining all rely on such detail to get a polished look. Without accuracy, you simply won’t get that professional, finished look that you expect. 

MASTERING THE TRICK

There’s not too much to it. If you can count to ten, then you’ve already mastered this trick. This DIY hack is easy to do for any inside measurement and will not only make it more straightforward for you but more accurate too. If you enjoyed this trick, you would also like my specialized guide for do-it-yourselfers that is full of these types of tips and covers many of the most requested solutions to home repair problems.