EC to TDS (PPM)

How to Calculate TDS from Electrical Conductivity

Electrical Conductivity ($\mu S/cm$) represents the water's ability to conduct electricity, while Total Dissolved Solids (TDS) is an estimated physical mass of dissolved minerals. Because meters actually measure EC and convert it to a PPM value internally, an accurate conversion factor is crucial. This EC to TDS calculator acts as a highly precise EC to PPM converter by utilizing non-linear laboratory calibration curves to give you accurate parts per million across all concentration ranges. If you already know your concentration and need to calculate the electrical conductivity instead, you can easily reverse the math using our PPM to MicroSiemens calculator.

The 500 vs 700 PPM Scale Explained

The number one point of confusion in water quality testing and managing a hydroponics nutrient solution is the difference between calibration scales. As is critical when using any of our water quality calculators, it is important to remember that meters do not measure PPM directly; they measure conductivity and apply a conversion ratio:

• us/cm to ppm 500 scale (Hanna): Assumes 1.0 mS/cm (1,000 µS/cm) equals 500 PPM. Uses an average conversion factor of 0.50. Widely used in general testing and European agriculture.
• ec to ppm 700 scale conversion (Truncheon): Assumes 1.0 mS/cm equals 700 PPM. Uses an average conversion factor of 0.70. This is the industry-standard scale in North America for hydroponic cultivation.

NaCl vs 442 Conversion Factor

Professional laboratory meters rely on standard chemical profiles to model water composition accurately. If you need to convert microSiemens to PPM with precision, understanding the NaCl vs 442 conversion factor is critical: