Method / version 1.0
Transparent math, deliberately modest claims.
A useful calculator should make the arithmetic faster without hiding the decision that still belongs to the gardener.
The four-step method
- 01Normalize the measurement
Inputs are converted to one internal unit before arithmetic. Metric and imperial examples are tested against the same physical volume.
- 02Expose the formula
Each tool page states the relationship it calculates. Results separate base volume from optional reserve where relevant.
- 03Test known cases
Automated tests cover reference geometries, unit equivalence, rounding, date arithmetic, plant-grid counts, and water-volume conversion.
- 04Mark the boundary
The result text identifies factors the model cannot observe and points to a suitable source for site-specific judgment.
Reference conversions
| Relationship | Value used | Where it appears |
|---|---|---|
| Cubic foot to liters | 28.316846592 L | Soil, mulch, containers |
| Cubic yard to liters | 764.554857984 L | Bulk soil and mulch |
| U.S. gallon to liters | 3.785411784 L | Rain capture, irrigation |
| 1 inch over 1 sq ft | 0.623376 U.S. gal | Rain capture, irrigation |
| Square meter to square feet | 10.7639104167 sq ft | Metric irrigation area |
Reserve and rounding rules
Material reserves are user-controlled and capped in the calculation layer to prevent accidental extreme inputs. Bag counts always round up to whole bags. Display rounding never changes the higher-precision value used for downstream conversion.
Plant-layout previews are geometry checks. They do not claim that every mathematically available point is horticulturally sensible. Date windows are broad defaults anchored to a frost date supplied by the user, not a location forecast.
Corrections and versioning
When a formula or source changes, the affected page’s review date should change with it and the test suite should gain a case that protects the correction. See the editorial policy or report an issue.