How the calculation works
Cost per year = shaves per week × 52 × price ÷ (blades in the pack × shaves per blade); the handle pays for itself after its price ÷ the difference per shave
A worked example
At 5 shaves a week, cartridges at $28.99 for 8 (7 shaves each) cost $134.60 a year; double-edge blades at $10.99 for 100 (4 shaves each) cost $7.14 a year — $127.45 less. A $30.00 safety razor handle pays for itself after about 12.2 weeks.
The handle is a one-off, the blades are not
A safety razor costs more on the first day and less every week after: double-edge blades usually cost a fraction of a cartridge per shave. The break-even shows how many weeks of shaving it takes before the cheaper blades have paid for the handle.
Compare like with like
Use your own shaves per blade for both. A double-edge blade often lasts fewer shaves than a cartridge, which this calculator takes into account rather than comparing pack prices.
Common questions
What if cartridges come out cheaper?
Then the handle never pays for itself at these prices, and the calculator says so. That happens with expensive blades or very few shaves per blade.
Can I compare disposables instead of cartridges?
Yes. Enter the disposables' pack price, the razors in it and how many shaves one lasts you in the cartridge fields.
Method: arithmetic from the label values you enter. Reviewed .