TDS Calculator
Estimate total dissolved solids (TDS) from a water's mineral analysis. Enter each ion in milligrams per litre to get a category-banded TDS estimate.
Estimated TDS
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How TDS relates to dissolved minerals
Total dissolved solids is the sum of all minerals, salts and metals dissolved in water, measured in milligrams per litre (mg/L) or parts per million (ppm). For bottled mineral water the major contributors are bicarbonate, calcium, magnesium, sodium, sulphate, chloride and potassium.
This calculator sums the five most commonly reported cations and bicarbonate to give a fast estimate. A full lab TDS will also include sulphate, chloride and silica, so the true value is typically 5–20% higher than the estimate.
TDS categories
- • < 50 mg/L — very low, soft
- • 50–150 mg/L — low
- • 150–500 mg/L — medium, balanced mineral water
- • 500–1500 mg/L — high mineral content
- • > 1500 mg/L — very high, therapeutic
