Swimming pool volume calculator for rectangular, oval, round, and sloped pools. Includes fill-cost estimate and chlorine dosing.
Four shape tabs (rectangle / oval / round / slope), each computing volume in cubic meters / liters / gallons, fill cost based on local water rate, chlorine dose (shock vs. maintenance), and time-to-fill.
Disclaimer: Chlorine estimates use a 1-3 ppm baseline. Consult a pool professional for full water-chemistry balance.
Calculator information
📋 How to use this calculator
- Choose pool shape: rectangle, oval, round, or sloped (varying depth).
- Enter dimensions in feet: length, width/diameter, and average depth.
- For sloped pools, enter shallow and deep end depths separately for automatic averaging.
- Enter your local water rate ($/1000 gallons) based on residential tier; default $4.00 per 1000 gallons (US average).
- Click Calculate for volume (cubic feet, gallons, liters), estimated fill cost, and chlorine dosage.
- Choose shock treatment mode (10 ppm) or daily maintenance (2-4 ppm) for correct chlorine dosing.
🧮 Geometric Volume and Chlorine Dosing (CDC/MAHC)
Rectangle: V = L x W x D ; Round: V = pi x r^2 x D ; Oval: V = pi x (a/2) x (b/2) x D ; Chlorine (oz) = Volume(gal) x Target(ppm) / 10000 / (active strength%)
- V = pool volume (cubic feet); 1 cubic foot = 7.48 US gallons = 28.32 liters
- L, W = length and width; D = average depth (ft)
- a, b = major and minor axes of oval; r = radius
- Target ppm = 2-4 (routine), 10 (shock); cal-hypo 60-70% active, liquid sodium hypochlorite 12%
For sloped pools, average D = (D_shallow + D_deep) / 2. Add 5-10% buffer for freeboard and evaporation.
💡 Worked example: Rectangular pool 26 x 13 x 5 ft, water rate $4.00/1000 gal
Given:- Shape: Rectangle
- Length 26 ft, width 13 ft, average depth 5 ft
- Water rate: $4.00 per 1000 gallons
- Chlorine maintenance target 3 ppm, cal-hypo 60% active
Steps:- V = 26 x 13 x 5 = 1690 cubic feet
- Volume in gallons = 1690 x 7.48 = 12,641 gal
- Fill cost = 12.641 x $4.00 = $50.56
- Chlorine = 12,641 x 3 / 1,000,000 x 8.34 lb/gal water density factor = approx 5.4 oz active
- Cal-hypo 60% = 5.4 / 0.6 = approx 9 oz
Result: Volume 1690 cu ft (12,641 gal / 47,860 L), fill cost approx $50.56, maintenance dose approx 9 oz cal-hypo 60% per application.
❓ Frequently asked questions
How often should pool water be completely replaced?
A well-maintained pool with proper filtration and chlorine does not need a full water change. Replace 10-20% of volume every 4-6 weeks to dilute TDS (Total Dissolved Solids). Full replacement is only needed when TDS exceeds 1500 ppm or after a severe algae bloom. Pools without filters need full water change every 2 weeks.
What's the difference between cal-hypo and liquid chlorine?
Calcium hypochlorite (cal-hypo) is a granule or tablet form with 60-70% available chlorine, suitable for both shock and maintenance, and raises pH and hardness. Liquid chlorine (sodium hypochlorite) is 12% strength, easy to dose but degrades quickly under UV. Trichlor tablets (90%) are popular for floating dispensers but lower pH.
Why is my pool water green even after adding chlorine?
Common causes: pH too high (>7.8) makes chlorine ineffective, free chlorine residual below 1 ppm, or excessive cyanuric acid (>50 ppm) binding chlorine. Fix: lower pH to 7.2-7.6 with muriatic acid, shock to 10 ppm overnight, and run the filter 24 hours.
What does it cost to fill a pool from municipal water?
US residential water rates average $3-6 per 1000 gallons, with sewer fees sometimes doubling the total. Large pool fills may trigger tiered/excess-use rates. Many utilities offer pool-fill exemptions on sewer charges if you call ahead. Check your local water authority before a major fill.
How long does it take to fill a pool with a garden hose?
A standard 5/8 inch garden hose delivers 9-17 gallons/minute (540-1020 gal/hour). A 12,641 gallon pool takes about 12-23 hours of continuous flow. For faster fills consider water-delivery trucks (typically 6000 gal per truck) to save time and avoid hitting peak tiered water rates.
📚 Sources & references
Last updated: May 11, 2026