EC to PPM calculator
Convert EC in mS/cm to the 500 or 700 scale used by your meter.
Use the result as a starting point.
Enter measured values, check the units, and keep the assumptions beside the answer. This tool supports a growing decision; it does not replace a calibrated meter, a product label, or observation of the crop.
Formula: PPM is approximately EC multiplied by the selected scale. The result is a meter convention, not a laboratory TDS analysis.
Record the PPM scale with every reading.
How to use this tool
Use this conversion when a meter or product label uses PPM but your notes use EC. The selected scale matters.
- Enter EC in mS/cm and choose the 500 or 700 PPM scale used by the meter.
- Enter the values, check the units, and select Calculate.
- Read the result as a planning estimate, then compare it with the crop and system.
Formula or reference method
PPM = EC x selected scale.
Worked example
At 1.40 mS/cm, the 500 scale gives 1.40 x 500 = 700 PPM. The 700 scale gives 980 PPM.
Understanding the result
The result is a meter convention, not a laboratory measurement of total dissolved solids.
Assumptions and limits
Different meters use different conversion assumptions. EC is the more direct conductivity measurement.
Common mistakes
Do not compare a 500-scale reading directly with a 700-scale chart. Record the scale with every reading.