The Basic Conversion
175 centimeters converts to approximately 5 feet 8.9 inches. You get there by dividing 175 by 2.54, since one foot equals exactly 30.48 centimeters or one inch equals 2.54 centimeters. The raw math gives you 68.8976 inches, which breaks down to 5 feet with 8.8976 inches remaining. Round it however you need to. The whole thing sounds more complicated than it actually is, but people still mess it up. I remember a contractor on a renovation job once measured a doorway at 175 cm and tried to frame the rough opening based on a mental approximation of 5'6". That's about a 2-inch error. The door wouldn't fit. He had to cut the header again. It cost him an afternoon and a couple of sheets of plywood. The actual conversion is straightforward, but the edge case that catches people isn't the math itself, it's working across measurement systems mid-project. You have a tape in centimeters, the plans are in feet, and you're trying to keep everything straight without a calculator handy. I just use the shortcut of dividing by 30 for a rough estimate, then adjusting. 175 divided by 30 is 5.83, which gets you very close to the real number without pulling out a phone.
For anything precision matters, like cabinetry or framing, I never trust mental math. I write it down on a scrap and double-check. The difference between 5'8" and 5'9" is one full inch, and that's the kind of thing that shows up as a gap you didn't plan for. There's also a quirk people miss when converting from metric to imperial. You're losing information with every conversion because the units don't align cleanly. 175 cm is an exact number in its system, but once you convert to feet and inches, you're dealing with a repeating decimal. That 0.8976 inch is the part that gets rounded away in casual conversation, and rounding it down to 8 inches instead of 9 can throw off something like a shelf spacing layout where cumulative error matters. I keep a small reference card in my toolbox with common conversions printed out. It's not fancy, but it saves me from having to compute on the spot when I'm juggling measurements. Most online calculators are fine for one-offs, but they slow you down if you're doing a bunch of them in a row. The manual method takes about three seconds once you've done it a few times.
