Crop Evapotranspiration (ETc = ETo × Kc) & Irrigation Gallons Calculator

Compute plant water demand ET_c = ET_o × K_c adjusted for irrigation efficiency.

Daily Irrigation Replacement Volume
747.96 gal/day
Net Crop Evapotranspiration (ET_c) 0.2 in/day
Gross Irrigation Depth Needed 0.24 in/day
Weekly Replacement Water Volume 5,235.72 gal/wk
Inputs
in/day
Reference grass evapotranspiration (ET_o) in inches/day.
K_c
Stage-specific crop coefficient K_c (0.4 initial, 0.85 mid, 1.15 peak).
sq ft
Irrigated turf or crop area in square feet.
%
Irrigation distribution uniformity / efficiency (85% drip, 70% rotor).
Results & Graph
Daily Irrigation Replacement Volume
747.96 gal/day
Net Crop Evapotranspiration (ET_c)
0.2 in/day
Gross Irrigation Depth Needed
0.24 in/day
Weekly Replacement Water Volume
5,235.72 gal/wk

Daily Irrigation Replacement Volume

Graph 1 • Reference Eto Inches Day Sensitivity Recalculates the domain equation across 50% to 150% of the primary input while holding other parameters constant.
0 gal/day 605.8 gal/day 1.2k gal/day 50%: 373.98 gal/day 374.0 50% 75%: 560.97 gal/day 561.0 75% 100%: 747.96 gal/day 748.0 100% 125%: 934.95 gal/day 935.0 125% 150%: 1,121.94 gal/day 1.1k 150%
Graph 2 • Primary & Supporting Metric Comparison Compares the primary output alongside supporting domain benchmarks.
Daily Irrigation Replacement Volume 747.96 gal/day Net Crop Evapotranspiration (ET_c) 0.2 in/day Gross Irrigation Depth Needed 0.24 in/day Weekly Replacement Water Volume 5,235.72 gal/wk
Graph 3 • Exact Output Table & Units Displays each calculated output in its exact domain unit.
Daily Irrigation Replacement Volume747.96 gal/dayNet Crop Evapotranspiration (ET_c)0.2 in/dayGross Irrigation Depth Needed0.24 in/dayWeekly Replacement Water Volume5,235.72 gal/wk
Summary: At ET_o=0.24"/day and K_c=0.85, net crop evapotranspiration ET_c is 0.204"/day (0.24"/day gross at 85% efficiency), requiring 748 gal/day across 5000 sq ft.
Summary: At ET_o=0.24"/day and K_c=0.85, net crop evapotranspiration ET_c is 0.204"/day (0.24"/day gross at 85% efficiency), requiring 748 gal/day across 5000 sq ft.
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Formula & Mathematical Methodology: Crop Evapotranspiration Formula

ETc = ReferenceETo × CropCoefficientKc
GrossIrrigation = ETc / SystemEfficiency
ET_c = Reference_ET_o × CropCoefficient_K_c; GrossIrrigation = ET_c / SystemEfficiency
  • referenceEtoInchesDay: Reference Eto Inches Day (in/day)
  • cropCoefficientKc: Crop Coefficient Kc (K_c)
  • plantedAreaSqFt: Planted Area Sq Ft (sq ft)
  • irrigationEfficiencyPct: Irrigation Efficiency Pct (%)

Rounding: Physical package counts round up where appropriate; continuous measurements round to 2 decimal places.

Worked Example: Practical Benchmark: Crop Evapotranspiration

Compute plant water demand ET_c = ET_o × K_c adjusted for irrigation efficiency.

  1. Enter your project dimensions, machining speeds, or recipe weights.
  2. Compute the governing equation: ET_c = Reference_ET_o × CropCoefficient_K_c; GrossIrrigation = ET_c / SystemEfficiency.
  3. Review the primary result, supporting dimensions, and 3 SVG visualizations.
Result: Computes Crop Evapotranspiration via ET_c = Reference_ET_o × CropCoefficient_K_c; GrossIrrigation = ET_c / SystemEfficiency.

Frequently Asked Questions

How does the Crop Evapotranspiration (ETc = ETo × Kc) & Irrigation Gallons Calculator calculate results?

It evaluates ET_c = Reference_ET_o × CropCoefficient_K_c; GrossIrrigation = ET_c / SystemEfficiency directly in your browser and plots three custom SVG visualizations.

Can I compare different material dimensions or batch sizes side by side?

Yes. Click "Compare (0/3)" in the results toolbar to pin up to 3 scenarios side by side.

Can I print a clean shop or kitchen reference sheet?

Yes. Click the Print button in the results toolbar for a distraction-free worksheet.

Science & Engineering · Agronomy & Environmental Science

Crop Evapotranspiration (ETc = ETo × Kc) & Irrigation Gallons Calculator: inputs, method, and how to read the result

Compute plant water demand ET_c = ET_o × K_c adjusted for irrigation efficiency.

Choose inputs for the case you are checking

The defaults are illustrative. Replace them with values for your case and keep the units shown beside each field.

  • Reference Eto Inches Day: Reference grass evapotranspiration (ET_o) in inches/day.
  • Crop Coefficient Kc: Stage-specific crop coefficient K_c (0.4 initial, 0.85 mid, 1.15 peak).
  • Planted Area Sq Ft: Irrigated turf or crop area in square feet.
  • Irrigation Efficiency Pct: Irrigation distribution uniformity / efficiency (85% drip, 70% rotor).

What the calculation includes

With the default values shown, Daily Irrigation Replacement Volume is 747.96 gal/day. The calculation follows Crop Evapotranspiration Formula; the formula and variable definitions above show how the inputs combine.

One-input check: With the other defaults held constant, changing Reference Eto Inches Day from 0.24 in/day to 0.26 in/day changes Daily Irrigation Replacement Volume from 747.96 gal/day to 810.29 gal/day. This is a comparison inside the calculator's stated model, not a prediction.

Where to use caution

  • Uses standard North American & metric trade dimensions, Machinery’s Handbook formulas, and culinary weight ratios.
  • Verify local municipal building codes, tool manufacturer limits, and food-safety time/temperature tables before execution.

Scope: Trade, Shop & Culinary Science Reference Standard Check the assumptions and limitations against your situation before relying on the estimate.

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