Pool Calculators
Every calculator on the site, grouped into the 4 clusters. 22 calculators total — read them as a single connected system, not separate lookups.
If you're here to find one number, jump straight to a calculator below. If you want the cluster's logic explained first — what to do in what order and why — the cluster hubs are the better entry point.
Pool Chemistry
11 calculators, in logical order. The hub explains the cluster's internal arc.
Pool Volume Calculator
Gallons or liters for any pool shape — rectangle, round, oval, kidney, L-shape, diving pool. The denominator of every other chemical, salt, and heater decision on the site.
Pool Salt Calculator
Pounds, 40-lb bags, or kilograms to hit your generator's target ppm — with brand presets from Intex, Hayward, and Pentair and the 'add 80% first' rule when the reading is uncertain.
Salt Chlorine Generator Calculator
What size salt cell you actually need — from your demand AND your pump hours, matched to sourced Pentair IntelliChlor and Hayward TurboCell ratings. The wedge generic pages miss: the box rating assumes 24-hour pumping, so on a normal 12-hour schedule the cell rated for your gallons can't keep up — size for your hours, not the label.
Saltwater Pool Conversion Cost Calculator
What converting a chlorine pool to saltwater actually costs — itemized SWG unit (sized to your pool) + salt charge (engine-exact lbs and bags) + install (DIY or pro) — AND an honest payback by your current chlorine spend. The wedge most pages bury: a salt cell wears out every ~5 years, so saltwater is cheaper chlorine, not free chlorine; a heavy spender recoups in ~2 yr, a light user may never.
Pool Chlorine Calculator
Exact dose for liquid, trichlor, dichlor, or cal-hypo — with the FC target your CYA actually demands (not a flat 3 ppm), plus the side-effect ledger every product adds.
Cyanuric Acid Calculator
Raise CYA with stabilizer dose for your gallons, or lower a runaway reading with a verified partial-drain plan. Five brand presets and the FC-cost ledger every CYA target carries.
Pool pH Calculator
Muriatic acid or dry acid to drop pH and TA together; soda ash to raise pH. With the CO₂-driven pH bounce-back finally explained — it isn't your dosing.
Pool Alkalinity Calculator
Baking soda to raise TA; acid + aeration to lower it without crashing pH. Matched pair to the pH calculator — same engine, two doors, asserted equal on every push.
Pool Calcium Hardness Calculator
Calcium chloride dose with the anhydrous-vs-dihydrate form gap disclosed — not averaged. Honest dilution math when CH needs to come down, because no chemical lowers calcium.
Pool LSI Calculator
Langelier Saturation Index from the full continuous saturation equation — with the cyanurate correction that turns a 'balanced' verdict into 'corrosive' when CYA is in the mix.
Pool Shock Calculator
SLAM dose keyed to your CYA, not a flat number. For algae: 40% of CYA. For chloramines: 10× combined chlorine. With the no-chlorine-floor case (drain, don't dose).
Pool Heating
4 calculators, in logical order. The hub explains the cluster's internal arc.
Pool Heater Size Calculator
BTU sizing with the two-number method (volume heats, surface area loses) and the cover wedge that saves 54,600 BTU every hour the pool sits. Honest range, never fake-precision.
Pool Heating Cost Calculator
Heat-up + monthly maintenance cost across gas, propane, heat pump, and electric resistance. The cover payback headline: about $719/mo saved, a $200 cover pays back in roughly 8 days.
Pool Evaporation Calculator
Vapor-pressure physics tied to your weather and humidity gives gallons-per-day and a leak-or-evaporation verdict. The cover wedge meets the heating wedge here: a cover cuts evaporation by ~90%.
Pool Heat-Up Time Calculator
Time to target with the honest climb: 15 hours where the rule of thumb said 10, because the pool sheds heat while it warms. Reverse mode answers 'warm by Saturday?' planning questions.
Pool Pump & Filter
4 calculators, in logical order. The hub explains the cluster's internal arc.
Pool Pump Run Time Calculator
Real turnover hours with the two truths the conventional advice misses: one turnover filters ~63 % (not 100 %, the 1 − e⁻ⁿ exponential mixing law), and the cube law makes slow-and-long dramatically cheaper than fast-and-short.
Pool Pump Size Calculator
Operating point solved by bisection root-finding — the flow you'll actually get, not the nameplate. Bigger pump barely helps (+18 % HP, only +9 % flow). Bigger PIPE wins (+15 % flow AND less water-power).
Pool Filter Size Calculator
Bigger filter is genuinely better — more area, slower rate, finer particle capture, longer cycles. The integrity wedge: the 48× area spread between sand and cartridge at the same flow, both correctly sized.
Pool Pump Cost Calculator
What your pump actually costs to run, and the honest variable-speed saving (~60 %, not the textbook 75 %). The cube-law two-part reconciliation: real friction is flow^1.852, and static head doesn't scale.
Pool Water & Filling
3 calculators, in logical order. The hub explains the cluster's internal arc.
Cost to Fill a Pool
What it actually costs to fill your pool — and the sewer-exemption money-saver no generic calc surfaces. Pool fill water doesn't enter the sewer; many utilities waive the sewer charge if you ask (~$240 → ~$100 on a 20k pool).
Pool Fill Time Calculator
How long it takes — about a day and a half on a typical hose, hose running overnight. With the bucket test (gpm = 300 ÷ seconds for a 5-gallon bucket) so the estimate is built on your hose, not a generic average.
Round Pool Gallons
The real manufacturer-published gallons for common Intex/Bestway/Coleman round above-ground pools — by diameter and wall height — because a 52″ pool holds water to ~45″, not 52″, and the same nominal size differs by brand. Sourced chart + measure-it fallback.