Ecology Calculators
Carbon footprint, energy use and other environmental calculations.
Vapor-Pressure-Deficit Calculator
Compute Temperature C, Relative Humidity Pct, Vpd, Saturation Vapor Pressure, Actual Vapor Pressure from Temperature C, Relative Humidity Pct, Vpd, Saturation Vapor Pressure. Free online Hong Kong ecology calculator.
Population-Growth-Rate Calculator
Compute Initial Population, Final Population, Rate Pct, Growth from Initial Population, Final Population, Rate Pct, Growth. Free online Hong Kong ecology calculator.
Net-Primary-Productivity Calculator
Compute Gross Primary Productivity, Respiration, Npp, Efficiency Pct from Gross Primary Productivity, Respiration, Npp, Efficiency Pct. Free online Hong Kong ecology calculator.
Daily-Light-Integral Calculator
Compute Ppfd, Light Hours, Dli from Ppfd, Light Hours, Dli. Free online Hong Kong ecology calculator.
Plant Population
Enter field area, plant spacing, row spacing, walkway width and plants per stand to compute total plants and density per m², for seedling demand and yield planning.
Plant Spacing
Enter equal spacing s and field area, choose square or triangular layout, to compute planting density (per m²) and total plants — for planning beds and nursery trays.
Gdu Calculator
Compute Max Temperature, Min Temperature, Base Temperature, Gdu, Mean Temperature from Max Temperature, Min Temperature, Base Temperature, Gdu. Free online Hong Kong ecology calculator.
ET₀ Calculator
Estimate daily reference evapotranspiration ET₀ (mm/day) with the Hargreaves method from daily max/min air temperature and extraterrestrial radiation Ra. Used for irrigation scheduling and crop water demand.
Leaf Area Index (LAI)
Enter total single-side leaf area and the ground area it covers (same unit) to compute the leaf area index LAI = total leaf area ÷ ground area, describing canopy density, light interception and transpiration.
Fertilizer-ppm Calculator
Compute Fertilizer Grams, Nutrient Percent, Water Liters, ppm, Nutrient Mass from Fertilizer Grams, Nutrient Percent, Water Liters, ppm. Free online Hong Kong ecology calculator.
Penman-Monteith Calculator
Compute FAO-56 reference evapotranspiration ET₀ (mm/day) from mean temperature, wind speed, relative humidity, net radiation and soil heat flux. The internationally recognized most accurate crop-water-demand baseline.
Harvest Index (HI)
Enter economic yield (dry weight of the harvested part) and biological yield (total aboveground dry matter) to compute harvest index HI = economic yield ÷ biological yield (0–1 and %), assessing dry-matter allocation efficiency.