How this calculator works
Conductivity reflects dissolved ions, while TDS includes dissolved material that may conduct poorly. The empirical conversion factor must be calibrated for the water and measurement temperature; 0.5 is an example input, not a universal constant. Analysis mode adds measured dissolved species without double counting. The sum-of-constituents estimate can differ from gravimetric residue because heating changes species such as bicarbonate. Suspended solids are excluded, and this tool does not judge drinking-water safety.
Formula
Conductivity estimate: TDS(mg/L) = factor x EC(uS/cm). Sum-of-constituents estimate: TDS = sum of dissolved anions, cations and other dissolved species.
Worked example
At conductivity 1000 uS/cm and factor 0.5, estimated TDS is 500 mg/L. Anion values 10 and 20 mg/L plus cation values 30 and 40 mg/L sum to 100 mg/L.
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Frequently asked questions
Is the factor always 0.5?
No. Composition and temperature affect it. Use paired measurements or a justified local calibration.
Can I add ion equivalents directly?
No. Convert every constituent to a mass concentration in mg/L before summing.
Does a low TDS prove water is safe?
No. Harmful microbes and some contaminants are not assessed by a dissolved-solids total.