Craftsman Laser Guided Measuring Tool, $35

The tool you need to most easily and accurately calculate things like how much paint, wallpaper, or flooring to buy. This model can add a room's dimensions together for you and figure square footage or cubic feet. Push a button for metric.

To Buy: www.craftsman.com.

Positioning the Tool: Hold it against the wall so the bubbles in the two built-in levels are centered. Make sure that no objects — especially anyone's eyes — block the path of the laser beam. (Staring directly into the beam can result in serious eye injury.)

Taking a Reading: A laser target is beamed onto the opposite wall; a digital readout then tells you the length or width of the room. If you're projecting onto a soft or very light-colored surface — an upholstered wall, glass, or a curtain — tape a piece of dark paper or cardboard to your target so the tool can sense its end point more easily.