Over five years, a cartridge habit costs somewhere between $136 and $514. A safety razor costs between $101 and $320. The ranges overlap, and the reason is the same on both sides: nobody agrees on how many shaves one blade is worth.

The first week with a safety razor isn't about nerve, and it isn't about the blade. It's about one number: roughly 30 degrees. On a standard razor you spend seven days finding it and holding it. On a fixed-angle razor there's nothing to find.

Razor burn is skin damage — it shows up minutes after shaving and fades within days. Razor bumps are hairs that re-entered your skin, and they arrive a day or two later and last weeks. An ingrown hair is one instance of that. The clock tells you which you have.

Any double edge blade fits any double edge razor. What changes between brands is the grind and the coating — and a blade doesn't go blunt, it chips. Here is what that means for choosing one, and which ones we ship.

Two weeks to get comfortable, about $7 a year in blades instead of $175, and a first week that is honestly a bit rubbish. The whole trade, including the part where we tell you not to bother.