Salt Water Dilution Calculator

Plan salt dilution before watering sensitive garden crops. Compare add-water and replace-water methods instantly here. Export CSV or PDF, and repeat with confidence daily.

Enter your values
Strength can be ppm, mg/L, or any consistent salinity measure.
Use replace when you must keep the container full.
All volume outputs use this unit.
Controls display precision in results and exports.
Example: 10 L, 5 gal, or 0.02 m3.
Use a single scale, like ppm or mg/L.
Must be lower than the current strength.
Use 0 for fresh water. Set higher for brackish.
Reset
Formula used
All formulas assume complete mixing and consistent strength units.
1) Add water (final volume increases)
C1*V1 + Cf*Vadd = C2*(V1 + Vadd)
Vadd = V1*(C1 - C2)/(C2 - Cf)
Valid when C1 > C2 > Cf.
2) Replace water (final volume stays constant)
C2 = (C1*(V1-x) + Cf*x)/V1
x = V1*(C1 - C2)/(C1 - Cf)
Remove x, then add x of lower-salt water.
How to use this calculator
  1. Measure current strength (C1) of your mix or source.
  2. Choose the desired target strength (C2) for watering.
  3. Enter your starting volume and select a unit.
  4. Set added-water strength (Cf). Use 0 for fresh water.
  5. Select Add water to increase volume, or Replace to keep volume constant.
  6. Press Submit to see results above the form and export.
Example data table
Illustrative scenarios for quick checking.
Method V1 (L) C1 (ppm) C2 (ppm) Cf (ppm) Water to add/remove (L) Final volume (L)
Add 10 2000 1000 0 Add 10.00 20.00
Replace 15 1500 900 0 Swap 6.00 15.00
Add 8 1200 800 100 Add 4.57 12.57
Replace 5 1800 1200 200 Swap 1.88 5.00
Tip: For plant safety, also consider drainage and leaching.

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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.