How the calculator works
Annual lawn-service cost equals the price per mowing visit multiplied by the number of visits per year. Robot-mower cost equals purchase price plus one-time setup plus annual maintenance over the selected period. Break-even is the point when cumulative avoided mowing-service cost exceeds the robot mower’s cumulative cost.
What the calculator intentionally leaves out
It does not assume a resale value, financing cost, electricity rate, battery replacement, inflation, or the value of your time. It also assumes the robot mower can replace the mowing portion of the service. If your landscaper bundles edging, fertilization, leaf cleanup, or other work, use only the mowing portion of that bill.
Use a conservative maintenance number
Blades are inexpensive on many machines, but batteries, wheel assemblies, shipping, and repairs can be material. If you are comparing a premium mower over a long horizon, increasing the annual maintenance allowance makes the estimate more conservative.