Gardening & Crops Calculators
Crop and plant physiology calculators compute daily light integrals (DLI), growing degree units (GDU), and soil cation exchange capacity for precision agricultural management.
This area splits into two families that often feed each other. The biology tools - daily light integral, vapor pressure deficit, water potential, photosynthesis and transpiration rates, growing degree units - describe what the plant is experiencing. The materials tools - soil, compost, mulch, seed, fertilizer, and spacing calculators - describe what you need to prepare or buy. A soil test result feeds the fertilizer calculator; plant spacing feeds plant population, which in turn feeds seed quantity and yield estimates. Gardeners usually arrive from the materials side, while growers running indoor rooms or planting schedules lean on the light and temperature tools.
The biology calculators make growing conditions comparable. Daily light integral accumulates light across a whole day instead of reading a spot value, and growing degree units accumulate warmth the same way; both turn a noisy series of readings into one number you can act on. Vapor pressure deficit and water potential describe the same drying pressure from two vantage points, the air above the leaf and the soil around the roots, which is why indoor growers and irrigators reach for them at different points in the season. None of this replaces a soil lab or a local extension recommendation, but it explains why those recommendations produce the numbers they do.
Start here
Three picks, one per job: start with the one that matches what you came to calculate.
- Turn a soil test into a fertilizer order: Fertilizer Calculator: every amendment purchase in the group starts from the test numbers
- Size a lawn before buying seed: Grass Seed Calculator: area to pounds, ounces and bags in one pass
- Work out how much mulch a bed needs: Mulch Calculator: the most common bag-count purchase around a garden
Calculators
Reading the soil and feeding it
Ordering mulch, soil and pots
Laying out beds, seed and companions
Starting and covering a lawn
Running the grow room's climate
Heat, harvest and grain numbers
Guides & explainers
Each guide goes deep on the science behind one or two calculators and links straight into them.
- Soil Cation Exchange Capacity (CEC) & Base Saturation Guide
- Daily Light Integral (DLI) & PPFD Guide
- How Much Compost Do You Actually Need? A Simple Formula
- Understanding VPD and Why It Matters for Grow Rooms
- Growing Degree Units Explained for Farmers
- Square-Foot vs Row Gardening: Plant Spacing Compared
- Reading a Soil Test: What the Numbers Actually Mean
Which tool do I need?
| If you need to… | Use | Why this one |
|---|---|---|
| if you need pounds of seed for a measured lawn | Grass Seed Calculator | new or overseed rates by grass type, with ounces and bags to buy |
| if you need fertilizer rates from a soil test | Fertilizer Calculator | test values converted to pounds per thousand square feet |
| if you need bushels and tons per acre before harvest | Corn Yield Calculator | ears, kernels per ear and the bushel factor in one pass |
| if you need bushels turned into pounds and tonnes | Grain Conversion Calculator | standard weights for five crops or your own measured test weight |
| if you need to know whether the crop has had enough heat | GDU Calculator | daily units, season totals and the modified 86 degree cap |
| if you need to check a grow room's light total | Daily Light Integral Calculator | photoperiod times intensity compared with published crop bands |
| if you need spacing worked out for beds and bulbs | Bulb Spacing Calculator | plants per row, per bed and per flat from the spacing you enter |
| if you need a sealed room's CO2 kept in range | CO₂ Grow Room Calculator | occupancy limits and supplemental injection rates together |
Gardening & Crops: common questions
Which calculator should I start with?
Start with the soil: the fertilizer page turns a soil test into an order, and the mulch, seed and spacing pages all need the same measured areas. Measure the beds and lawn once and reuse those figures across the whole group.
Where do the rates and formulas come from?
Each calculator cites the extension tables and standards behind its numbers, from university seeding rates and bushel weights to OSHA and NIOSH exposure limits. The sources section under every page names what each one was used for.
How do these pages handle units?
Soil, mulch and seed work in pounds and square feet, the yield pages move between bushels, pounds, tons and tonnes, and the climate tools use metric units such as micromoles and moles per square metre. Convert once at entry rather than afterwards.
Can I use these on a farm rather than in a garden?
Yes. Growing degree days, corn yield, grain conversion and acres per hour are straight field tools used at scale, while the seed, spacing and soil pages are calibrated for lawns, beds and gardens.
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