Water tools
TDS to conductivity converter
Convert electrical conductivity to total dissolved solids and back, using the correlation factor for your water type. A fast estimate for feed-water characterisation, RO design, and cooling-water control.
Using TDS = 0.65 × EC. Estimate only; confirm with a gravimetric measurement.
How it works
Total dissolved solids and electrical conductivity are linearly related for a given water: TDS (mg/L) = k × EC (µS/cm), where k is a correlation factor that depends on the ionic make-up of the water.
The factor is not universal. For sodium-chloride-dominated brackish water it is around 0.50; for natural mixed waters it sits near 0.65; for high-salinity seawater it is around 0.70. Use a site-specific factor from a paired lab measurement of gravimetric TDS and conductivity when you have one.
Conductivity here is in microsiemens per centimetre (µS/cm); 1 mS/cm = 1000 µS/cm. The result is an estimate, not a substitute for a gravimetric TDS at 180°C.
Source: standard TDS-conductivity correlation (see, for example, APHA Standard Methods 2510 and 2540).
Related reading
These calculators use standard published formulas and are provided for preliminary engineering guidance. Confirm against measured data and vendor projections before design. Model your full water matrix in Nepti or post your project to compare provider proposals.