You can measure most things in the physical world with centimeters and inches. A standard ruler handles both—but it ignores digital environments, which render in pixels, and typefaces, which print in picas.

Designers who work with all four units either excel at mental math (a 12-point font is one pica, or 0.167 inches, tall), or, more likely, own a bunch of rulers. "I used to have five," says Axel Lindmarker, a student at the School of Visual Arts in New York. Too many, he thought. So, along with fellow student Jens Marklund, he designed one rule to rule them all. They call it the Lindlund (Lind__marker + Mark__lund). Inches and centimeters run along its outer edges, pixels and picas along the narrow rectangle that cuts through its middle.

Lindlund

They also marked the central window with iPhone and iPad screen dimensions. These make it easier for designers to dream up digital apps in the pages of a notebook. No matter how hard gadget makers push tablets as creative tools, most designers still prefer to brainstorm with pen and paper. Computers are great for refining and perfecting—but that comes later. “It feels easier to get the idea out there," says Lindmarker, who starts all his projects on paper. "If you want to draw a star you just draw it.”

The Lindlund ($25 on Kickstarter) is designed to keep those early sketches to scale, sparing you revisions on the computer later. In that light, the ruler really is, as Lindmarker and Marklund call it, a bridge between the digital and physical world. But it's clear where the pair's loyalties lie. “There’s something about the physicality of paper,” Lindmarker says. “It helps you think.”