TDS Calculator

The TDS Calculator determines total dissolved solids (TDS) in water from either a full chemistry analysis or an electrical conductivity (EC) reading. TDS is a key water quality parameter affecting taste, salinity, and suitability for drinking or industrial use.

From water chemistry analysis

Sum all reported anion and cation concentrations in mg/L:

$$\mathrm{TDS} = \sum \mathrm{anions} + \sum \mathrm{cations}$$

From electrical conductivity

When only an EC meter is available, approximate TDS using:

$$\mathrm{TDS\ (mg/L)} = k \times \mathrm{EC\ (\mu S/cm)}$$

The conversion factor $k$ typically ranges from 0.55 to 0.8; 0.67 is a common default for natural waters. For water at standard conditions, mg/L and ppm are equivalent.

Drinking water TDS guidelines are generally 500-1000 mg/L. Below 1000 mg/L is freshwater; above 35,000 mg/L is hypersaline.

Frequently Asked Questions

What are total dissolved solids?

TDS is the sum of all ionic particles smaller than 2 μm dissolved in water, including salts, minerals, and metals. It is expressed in mg/L or ppm.

How do I convert EC to TDS?

Multiply the electrical conductivity in μS/cm by a conversion factor k (typically 0.67). TDS = k × EC gives an approximate TDS in mg/L.

Is TDS the same as ppm for water?

Yes, for water at standard conditions where density is approximately 1000 kg/m³, TDS in mg/L equals ppm.

What TDS level is safe for drinking water?

Acceptable drinking water TDS is typically 500-1000 mg/L. Below 500 mg/L is low mineral water. Above 1000 mg/L may affect taste and quality.

Report

TDS Calculator

TDS Calculator

From water chemistry analysis

From electrical conductivity

Frequently Asked Questions

Related Tools

Recent Visits