Water Budget Calculator for Gardens

Balance irrigation and rainfall for thriving beds. Set efficiency and flow to plan accurate runtimes. Stay within your water limit and reduce waste weekly.

Water budget inputs
Enter values for your planning period, then calculate.
Used to convert depth into volume.
From local weather or station data.
Typical range: 0.30 to 1.10.
Examples: 7, 14, or 30 days.
Enter average or total for the period.
Drip often 85–95, sprinklers 60–80.
Useful for heavy rain that exceeds storage.
Optional: leaching or distribution losses.
Compare calculated need to your target limit.
Used to estimate irrigation runtime.
Helps suggest events over the planning period.
Example data table
Sample inputs and typical outputs for comparison.
Scenario Area (m²) ET₀ (mm/day) Kc Days Rain (mm/day) Eff (%) Gross (L)
Vegetables, mild week 25 4.0 0.85 7 1.0 85 ~595
Mixed beds, two weeks 40 4.5 0.75 14 0.5 80 ~2,310
Fruit shrubs, dry month 60 5.5 0.70 30 0.0 70 ~6,930
Table values are rounded and simplified for illustration.
Formula used
These equations power the calculator.
How to use this calculator
  1. Enter your garden area and select the unit.
  2. Provide reference ET and the plant factor value.
  3. Choose the planning period and add rainfall details.
  4. Set system efficiency to convert net to gross water.
  5. Optionally add flow to estimate irrigation runtime.
  6. Press calculate and review totals and event timing.
  7. Use budget balance to tighten or relax targets.
  8. Download CSV or PDF to save your record.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.