Calculate Pool

Use this when someone asks how much of a pool chemical to add to go from a current to a target level: chlorine (liquid chlorine 12.5 %, bleach 10 % or 6 %, cal-hypo 65 % or 73 %, dichlor, trichlor) for free chlorine; salt for a salt chlorinator; baking soda to raise or muriatic acid to lower total alkalinity; stabilizer (cyanuric acid); calcium chloride for calcium hardness; muriatic acid to lower pH or soda ash to raise it. Levels in ppm (pH for the pH chemicals). Returns the amount in fl oz, oz or lb, a readable amount, the number of common packages, the factor used and a safety line. Not for shock targets or water-balance (LSI) questions.

Use this when someone asks what size pool heater (BTU per hour) they need to raise the water a number of degrees Fahrenheit in a given time. Takes gallons, the temperature rise in °F and the hours (default 24), plus an optional buffer for surface heat loss (default 20 %, the same as the heater calculator on calculatepool.com). Returns the BTU/h required, the size with the buffer, the total BTU and the electric input of an equivalent heat pump. Not for heating cost per month or heater model recommendations.

Use this when someone asks how many gallons a common pool size holds, e.g. a 24 ft round above-ground pool with a 52 in wall or a 16 x 32 inground pool, or wants a table of standard sizes. Returns inground rectangles (12x24 to 25x50 ft at 3.5, 4.5 and 5.5 ft average depth) and above-ground round and oval pools (12-33 ft round, 12x24 to 21x41 ft oval at 48, 52 and 54 in walls) with the factors used. For any other size or shape use pool_volume.

Use this when someone wants to know how many gallons (or litres, cubic feet) a swimming pool holds from its shape and size: rectangle, round, oval, Roman, Grecian, kidney, L-shape or freeform, with one depth, a shallow and a deep end, or an above-ground wall height (48, 52, 54 in). Dimensions in feet or metres. Returns gallons, litres, cubic feet, cubic metres, surface area and the formula. Use it before chemical_dose, pump_size or heater_size when only dimensions are known.

Use this when someone asks what size pool pump they need or what flow rate turns their pool over in a given number of hours. Takes gallons and turnover hours (default 8). Returns gallons per minute, gallons per hour, a rule-of-thumb horsepower range, the minimum sand, cartridge and DE filter area for that flow, and pipe velocities. Not for electricity cost or pump model recommendations.