The reference shelf
All calculators
5 free tools, no sign-up — each one cites its extension-service sources and shows its working.
Garden
05 tools
Garden
Compost Calculator
Calculate your compost C:N ratio, bin volume, and get balancing recommendations.
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Garden
Watering Schedule Calculator
Get a personalized watering schedule based on your plant, soil, season, and growing method.
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Garden
Soil pH Calculator
Calculate how much lime or sulfur you need to reach your target soil pH.
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Garden
Seed Spacing Calculator
Calculate recommended row spacing, plant spacing, and total seed count for your garden.
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Garden
Fertilizer Calculator
Calculate NPK fertilizer dosage for any crop or garden area.
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