There are so many recipe elements that call for a measurement of inches or increments of inches. In the test kitchen, we keep rulers around for just these times (which is EVERY DAY!). At home, you may not need to keep up with a ruler if you have a chef, paring, or other kitchen knife with rivets (technical term for the metal dots) on the handle. Although varied in some cases, a majority of knives with 3 rivets have spacing of 1 inch between rivets. That means you are likely using a 3-inch ruler every time you cut something and can compare your julienne-cut carrots to your rivets to see if they are the right length. Take a measurement on your rivets and commit that to memory and you have doubled the value of your knife!
Photo © Danilo Alfaro, courtesy of About.com. Find more great knife tips in Danilo Alfaro's The Anatomy of a Chef's Knife.