TDS Calculator
Estimate total dissolved solids from conductivity.
Estimate dissolved solids in water from an electrical conductivity reading.
How the Math Works
The TDS Calculator uses the fundamental relationship TDS = conductivity × factor to convert electrical conductivity measurements into total dissolved solids. Conductivity, measured in microsiemens per centimeter (µS/cm), indicates how well water conducts electricity, which depends on the concentration of dissolved ions. The conversion factor accounts for the fact that not all conductive substances contribute equally to TDS; different ion types (like calcium, magnesium, sodium) have varying contributions, so the factor serves as an empirical adjustment.
Practical Applications
To use this calculator practically, first measure the water's electrical conductivity using a portable TDS meter or conductivity probe. Select the appropriate conversion factor based on your water type - factors typically range from 0.5 to 0.8 for standard drinking water applications. Simply multiply your conductivity reading by the chosen factor to obtain the TDS value in parts per million (ppm) or milligrams per liter (mg/L), allowing you to quickly assess water quality without complex laboratory analysis.
Day-to-Day Use
This calculation helps you make informed decisions about drinking water safety and quality in everyday situations. By estimating TDS levels, you can determine if your tap water needs filtration, whether it falls within the acceptable range of 50-150 ppm for palatability, or if bottled water might be preferable. It's useful for cooking (hard water affects taste), gardening (plant nutrient uptake), aquariums (maintaining proper water chemistry), and monitoring well water quality over time to catch potential contamination issues early.
Worked example
500 µS/cm × 0.65 → 325 ppm.
FAQ
Drinking water?
TDS below ~500 ppm is generally considered good.