Total Dissolved Solids Calculator

Work out total dissolved solids instantly with clear inputs, formula shown and shareable results.

About Total Dissolved Solids Calculator

Conductivity meters estimate TDS by multiplying by a factor of 0.55-0.75 that depends on the ionic composition of the water. The definitive method is gravimetric: evaporate a known volume and weigh the residue. Comparing the two gives the site-specific factor, which should be established rather than assumed.

Formulas

TDS from conductivity

TDS (mg/L) = conductivity (microS/cm) x conversion factor

Gravimetric TDS

TDS = residue (g) x 1,000,000 / sample volume (mL)

Worked example

With the default values below, Total Dissolved Solids Calculator returns TDS From Conductivity of 520.000. Change any input above and every figure here is recalculated in your browser.

Inputs used

Electrical Conductivityminimum 0 microS/cm: 800 microS/cm
TDS Conversion Factoraccepts 0.01–1: 0.65
Gravimetric Residueminimum 0 g: 0.52 g
Sample Volumeminimum 0 mL: 1,000 mL

Results

TDS From Conductivity: 520.000
TDS By Gravimetric Method: 520.000
Implied Conversion Factor: 0.65000
Palatability Assessment: Good

Step by step

1Values used
2TDS from conductivity
3Gravimetric TDS
4TDS From Conductivity= 520.000
5TDS By Gravimetric Method= 520.000
6Implied Conversion Factor= 0.65000
7Palatability Assessment= Good

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 5 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why does the conversion factor vary?

Different ions carry current differently. Water dominated by sodium chloride has a higher factor than water dominated by bicarbonate, so a single factor cannot serve all sources.

Is there a health limit for TDS?

No health-based guideline value, but palatability declines above about 600 mg/L and most standards set an aesthetic limit around 500-1000 mg/L.