Free planning tools · Plan servicing and costs
Off-grid toilet ownership-cost comparison
Compare upfront costs, annual running costs and scheduled replacements over the same ownership period.
No account needed. Results update here as you change the inputs. Measurements stay in this tab unless you choose to share a link; shared links contain the inputs, including any location coordinates.
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Compare a change before committing
Keep this plan, change the inputs and see the difference. The comparison stays in this tab.
How do the toilet options compare over the years you will own them?
A lower purchase price and a lower ownership total are different questions. Enter each option’s upfront, annual and replacement costs over the same period to compare the cash costs you expect, without a live price feed or invented savings claims.
The cumulative chart and year-by-year table show how the comparison develops. Use an operating-cost figure from the running-cost tool, and keep assumptions consistent when discussing a shortlist with another owner.
How to use this planner
- Add at least two named options using your own comparable prices.
- Set a common period and any recurring replacement interval.
- Read total components and the year-by-year view, then compare practical suitability separately.
The calculation
Total = purchase + installation + annual operating cost × years + replacement events strictly before the end of the period × replacement cost. Costs share one currency, without inflation or discounting.
A worked example
Over five years, an 800 purchase, 100 installation, 50/year operation and a 100 replacement every three years totals 1,250. A 200 purchase, 50 installation and 120/year totals 850.
Example inputs are demonstrations. Replace them with your own measurements, prices or documented requirements.
Assumptions and limits
All example prices are fictional. Use your running-cost calculation for each annual figure. Replacement intervals can be fractional years; zero means none. Events exactly at the period end are excluded. Resale, financing, inflation, downtime and disposal fees are excluded unless you include them in the appropriate inputs. This compares cash costs, not suitability.
Questions about this calculation
Does the lowest total identify the most suitable toilet?
No. It identifies the lowest entered cash cost. Space, service effort, ventilation, capacity, disposal arrangements and comfort can matter more than the difference shown.
How are replacements at the end of the period counted?
The model counts replacement events strictly before the chosen period ends. An event exactly at the end is excluded. The same convention applies to each year shown in the cumulative table; inflation and discounting are not modelled.
Put the result in context
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