Credits and licences

Last updated 2026-10-11

Our own code

The tools and page layouts are written for this site. The pages make no requests to other servers.

The calculators use published constants and textbook formulas, typed into our own code (no third-party tables or libraries are copied):

Area units: exact definitions (1 acre = 4,046.8564224 m² = 43,560 ft²; 1 ha = 10,000 m²) from NIST SP 811 and Handbook 44; US bushel = 2,150.42 in³.
Field capacity: the ASABE formula C = S × W × E ÷ 8.25 (acres per hour); field efficiencies are entered by the user (typical ranges are published in ASABE D497).
Sprayer calibration: the standard GPA = 5,940 × GPM ÷ (MPH × nozzle spacing in inches) and its metric form, as taught in university extension calibration guides.
Fertilizer analyses: standard product grades (N-P2O5-K2O) as printed on product labels; P2O5 → P and K2O → K factors from IUPAC atomic weights.
Bushel weights: USDA standard test weights per bushel (corn 56 lb, soybeans and wheat 60 lb, and others).
Irrigation: application rate in/h = 96.3 × gpm ÷ ft²; 1 acre-inch = 27,154 US gallons.
Gestation, hay intake and bale weights: typical planning values that the calculators let you change.

None at present. If we add any library, font or data set, it will be listed here with its licence and a link (data/credits.json, rendered below).