LSI (Langelier Saturation Index) calculator
PROLangelier Saturation Index — target between -0.3 and +0.3.
Short answer: LSI = pH + TF + CF + AF − TDS constant. pH 7.5, 78°F, CH 250, TA 100, TDS 1000 → LSI ≈ 0.0 (balanced). Enter your measurements above and the lsi (langelier saturation index) calculator returns the quantity, unit conversions and an estimated cost instantly, in imperial or metric — no sign-up needed.
What do you need to measure?
What is the answer?
LSI
-0.19
Balanced
How does the lsi (langelier saturation index) calculator work?
LSI = pH + TF + CF + AF − TDS constant.
What does a worked example look like?
pH 7.5, 78°F, CH 250, TA 100, TDS 1000 → LSI ≈ 0.0 (balanced).
What do people ask most?
›Target range?
-0.3 to +0.3. Below = corrosive; above = scale forming.
Which pool calculator should you use next?
Where can you learn more?
Read field notes on estimating and materials, or browse every calculator we make.
What should you read before you order materials?
Field notes from real jobs that explain the numbers behind this calculator.
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