Volume & Water Use
Estimate pool or hot-tub capacity, convert measured evaporation to gallons and budget a partial or complete refill.
◈ Pool & Spa Calculator Category
Pool & Spa Calculators
Plan pool and spa water volume, chemistry, circulation, filtration, heating, water use and costs with 12 transparent calculators.
Showing all 12 pool and spa calculators.
Swimming Pool Volume Calculator
Estimate rectangular swimming-pool water volume from length, width, and shallow and deep-end depths.
Pool Chlorine Dose Calculator
Estimate the weight of a chlorine product needed to raise free chlorine by a chosen ppm amount.
Pool Pump Runtime Calculator
Calculate daily pool-pump runtime from water volume, measured flow rate and desired turnovers.
Pool Heating Cost Calculator
Estimate one-time pool-heating energy and fuel cost from water volume, temperature rise and heater efficiency.
Hot Tub Volume Calculator
Estimate round hot-tub water volume from inside diameter, average water depth and a fill-shape factor.
Pool Salt Calculator
Calculate salt weight needed to raise pool salinity from a current reading to a target ppm.
Pool Water Turnover Calculator
Calculate theoretical pool turnover time and turnovers per day from volume and filtered flow rate.
Pool Refill Cost Calculator
Estimate water and sewer charges for filling or partially replacing swimming-pool water.
Pool Heating Time Calculator
Estimate ideal pool warm-up time from water volume, temperature rise, heater output and efficiency.
Pool Evaporation Loss Calculator
Convert measured evaporation depth into estimated gallons lost across a pool surface and time period.
Pool Filter Flow Rate Calculator
Calculate required filtered flow rate from pool volume, target turnover time and a design safety factor.
Pool Langelier Saturation Index Calculator
Estimate pool-water Langelier Saturation Index from pH, temperature, TDS, calcium hardness and alkalinity.
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About Our Pool & Spa Calculators
This independent collection turns pool dimensions, water readings, equipment ratings and local prices into transparent planning calculations. Every page identifies inputs, units, equations, assumptions, rounding, limitations, colored result details, primary sources and dynamic calculation steps.
Chemistry & Circulation
Calculate chlorine and salt quantities, Langelier Saturation Index, pump runtime, turnover time and preliminary filter flow.
Heating & Costs
Compare ideal warm-up time, fuel input and estimated heating cost while keeping efficiency assumptions visible.
Pool and spa safety notice: These educational tools do not replace water testing, product labels, equipment instructions, local aquatic codes or qualified professional service. Never mix pool chemicals.
Pool & Spa Calculator FAQs
Yes. All 12 calculators run free in the browser without registration.
No. They provide transparent planning calculations. Test the water, follow product labels and local requirements, and consult a qualified pool professional when safety or equipment design is involved.
The tools use familiar U.S. pool-maintenance units such as gallons, feet, pounds, ppm, GPM, BTU and therms, with supporting metric values where useful.
The arithmetic can support either when the entered values and assumptions are appropriate, but public aquatic venues may be subject to specific local codes and operating requirements.
No. Calculations run locally in the browser and do not require an account.
Yes. Every successful result includes colored supporting values and at least five dynamic calculation steps; more are shown when needed.