PPM to EC calculator
Convert a PPM display back to estimated EC in mS/cm.
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.
Use it when: a meter or label gives PPM but your notes and crop references use EC. Conversions are estimates.
How to use this tool
Use this conversion when a meter or label gives PPM but your crop notes use EC. The selected PPM scale controls the estimate.
- Enter PPM and choose whether the reading uses the 500 or 700 scale.
- 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
EC = PPM / selected scale.
Worked example
A 750 PPM reading on the 500 scale is 750 / 500 = 1.50 mS/cm. On the 700 scale it is about 1.07 mS/cm.
Understanding the result
Use the EC estimate to compare references, then confirm decisions with your own calibrated meter and nutrient label.
Assumptions and limits
PPM is not a universal chemical concentration. Conversion factors vary by meter convention.
Common mistakes
Do not mix scale assumptions between readings or treat the result as a laboratory TDS analysis.