Formula
Total ownership cost = purchase price + installation + years × (electricity + consumables + maintenance reserve + subscription fees) + battery replacement cost × number of replacements − resale value.
The lawn-service comparison multiplies your service price per visit by annual visits and the selected number of years. It does not assign a dollar value to your own time, trimming, leaf cleanup, fertilizer, irrigation or other services that may be bundled with a lawn-care contract.
Use ranges, not one precise forecast
Run the calculator at least three times: an optimistic case with low repair spending, a base case, and a higher-cost case with an earlier battery replacement or larger maintenance reserve. That range is more useful than treating one five-year number as certain.
Battery replacement is optional
Set battery replacements to zero if you want a lower-bound estimate. Set it to one for a reserve-based scenario. For a longer horizon or a heavily used mower, test a second replacement rather than assuming the original battery lasts indefinitely.
Installation can materially change break-even
Wire-free systems may require only charging-station and reference-station setup, while traditional boundary-wire systems can involve substantial labor or professional installation. Enter the actual quote rather than assuming installation is free.
See the 5-Year Ownership Cost Index for standardized model-to-model scenarios, the Warranty & Parts Support Index for repair-path transparency, and the Price Index for current observed purchase-price comparisons.