# Pipe Volume Calculator Canonical URL: https://www.simplywise.com/blog/pipe-volume-calculator/ Plain text: https://www.simplywise.com/blog/pipe-volume-calculator/llms.txt Publisher: SimplyWise, Inc. (https://www.simplywise.com) Published: September 17, 2026 Updated: October 27, 2026 Summary: A pipe volume calculator that turns pipe size, material, schedule, run length and fill percentage into gallons, cubic feet, and the weight of the water. --- Log in (https://simplywise.com/login) ## Pipe Volume Calculator: Gallons, Cubic Feet, and Water Weight Nominal size is a label, not a measurement. Pick the material and schedule and the gallons, water weight and fill time update as you type. Add SimplyWise as a preferred source (https://www.google.com/preferences/source?q=simplywise.com) Gallons, cubic feet, water weight, fill time Material and schedule Nominal pipe size Run length (ft) Fill percentage Flow rate (gpm) 4.49 gallons of water, 1 in PVC Schedule 40 Internal volume0.6 cu ft Inside diameter1.049 in inside diameter Water weight37.4 lb of water Fill time54 sec at 5 gpm Volume per foot0.0449 gal per ft Inside diameters from published maker and association dimension tables, read September 11, 2026. Water at 8.34 lb per gallon. At a glance 1. Volume = pi times inside radius squared times length. Nominal size is not the bore. 2. Gallons = cubic inches / 231. Cubic feet = cubic inches / 1,728. 3. Water weighs 8.34 lb a gallon, so 100 ft of 2 in Schedule 40 carries 145 lb. 4. Schedule 80 shares an outside diameter with Schedule 40 and adds wall, so it holds less. 5. Copper Type K is the thickest wall and the smallest bore. Type M is the thinnest. 6. 100 ft of 1 in Schedule 40 holds 4.49 gallons, weighs 37.4 lb, fills in 54 seconds at 5 gpm. ## How the pipe volume calculator works A pipe is a cylinder, so volume is pi times the inside radius squared times the length. One part is hard: the inside radius is the number nobody has on hand, because pipe is sold by nominal size and nominal size is a label. Half inch Schedule 40 PVC measures 0.622 in inside. Half inch Type L copper measures 0.545 in. Feed 0.5 into Schedule 40 and the answer is low by a third. ## Worked example: 100 feet of 1 inch Schedule 40 The published bore is 1.049 in, so the radius is 0.5245 in and the bore area 0.864 square inches. Times 1,200 inches of run: 1,037 cubic inches. Divide by 231 and that is 4.49 gallons, or 0.6 cubic feet. At 8.34 lb a gallon the water weighs 37.4 lb, and at 5 gpm the run fills in 54 seconds. ## Inside diameter by size and schedule Published dimensions, in inches, off maker and association tables. | Nominal | PVC Sch 40 | PVC Sch 80 | Copper K | Copper L | Copper M | | --- | --- | --- | --- | --- | --- | | 1/2 in | 0.622 | 0.546 | 0.527 | 0.545 | 0.569 | | 3/4 in | 0.824 | 0.742 | 0.745 | 0.785 | 0.811 | | 1 in | 1.049 | 0.957 | 0.995 | 1.025 | 1.055 | | 1-1/4 in | 1.380 | 1.278 | 1.245 | 1.265 | 1.291 | | 1-1/2 in | 1.610 | 1.500 | 1.481 | 1.505 | 1.527 | | 2 in | 2.067 | 1.939 | 1.959 | 1.985 | 2.009 | Read one row across. At 2 in nominal the bore swings from 1.939 in to 2.067 in, and volume moves with its square. ## Why Schedule 80 holds less Schedule is wall thickness, not size. Both share an outside diameter, so the same fittings fit either. The thicker wall comes out of the bore. Two inch Schedule 40 runs a 0.154 in wall and a 2.067 in bore. Schedule 80 runs 0.218 in and 1.939 in. Six percent off the diameter is twelve percent off the volume. ## Turn the takeoff into a signed quote Sizing the pipe is the easy half. SimplyWise Cost Estimator turns a photo into an itemized estimate in about 6 seconds, with material and labor line items. Pricing is $29.99/mo or $239.99/yr, about $20/mo on annual, with a 7-day free trial. ## Copper Type K, Type L and Type M Copper water tube holds one outside diameter per size, always an eighth of an inch over nominal, with three wall thicknesses inside it. Type K is heaviest, Type L is the common service wall, Type M is thinnest. Three quarter inch copper runs a 0.875 in outside diameter in all three. Inside: Type K 0.745 in, Type L 0.785 in, Type M 0.811 in. That is 2.26 gallons per 100 ft against 2.51 against 2.68, and on a recirculating loop the wall sets what you pay to keep it hot. ## Water weight is the number that moves a job Water weighs 8.34 lb a gallon, off a published density near 62.4 lb per cubic foot. Nobody thinks about it on a half inch branch. It matters once the run is big. A hundred feet of 4 in Schedule 40 holds 66.13 gallons, so the pipe gains 551 lb the second it fills. Hangers and a wood joist both care. ## Run the pipe volume calculator in this order 1. Read the size and the schedule off the pipe The print carries both. Nominal size alone does not give you the bore. 2. Look up the published inside diameter Use the maker or association dimension table. Never a rounded nominal number. 3. Multiply the bore area by the run length Pi times radius squared times length in inches. Keep every unit in inches. 4. Convert, then weigh it Divide by 231 for gallons or 1,728 for cubic feet, then gallons by 8.34 for pounds. ## Keep reading - Construction Calculators: the full set (https://www.simplywise.com/blog/construction-calculators/) - Plumber Hourly Rate: what the number is built from (https://www.simplywise.com/blog/plumber-hourly-rate/) - How Much Does a Plumber Cost (https://www.simplywise.com/blog/how-much-does-a-plumber-cost/) ## Sources ### PVC inside diameters - Charlotte Pipe and Foundry, Dimensional Catalog, Plastics Pressure Systems (https://www.charlottepipe.com/uploads/documents/technical/DC-PR.pdf) (Pipe Data pages for PVC Schedule 40 Plain End and PVC Schedule 80 Plain End, both marked ASTM D 1785; average OD and minimum wall per row; read 2026-09-11). ### Copper tube inside diameters - Copper Development Association, Copper Tube Handbook, CDA Publication A4015-26/24 (https://copper.org/wp-content/uploads/2026/04/copper_tube_handbook_print_press.pdf) (Tables 14.2a, 14.2b and 14.2c, dimensions and physical characteristics of copper tube Type K, Type L and Type M; read 2026-09-11). ### Units and water density - NIST Handbook 44, 2026, Appendix C, General Tables of Units of Measurement (https://www.nist.gov/document/2026-nist-handbook-44-appendix-c) (1 gallon = 231 cubic inches exactly; read 2026-09-11). - USGS Water Science School, Water Density (https://www.usgs.gov/special-topics/water-science-school/science/water-density) (62.424 lb per cubic foot at 39.2 F, which works out to 8.34 lb per gallon; read 2026-09-11). ### Product - SimplyWise Cost Estimator, App Store (https://apps.apple.com/us/app/simplywise-cost-estimator/id6670619664) (4.8 rating; verified 2026-09-09). ## Common questions on the pipe volume calculator **How do I calculate the volume of water in a pipe?** Multiply pi by the inside radius squared by the length, all in inches. Divide by 231 for gallons or 1,728 for cubic feet. **How many gallons are in 100 feet of 1 inch pipe?** 4.49 gallons in Schedule 40 PVC, on a 1.049 in bore. Schedule 80 holds 3.74 and Type L copper 4.29. **Is nominal pipe size the same as inside diameter?** No. Half inch Schedule 40 PVC measures 0.622 in inside, half inch Type L copper 0.545 in. Use the published dimension. **Does Schedule 80 hold less water than Schedule 40?** Yes. Both share an outside diameter, so the thicker wall comes out of the bore. Two inch drops from 17.43 gallons per 100 ft to 15.34. **How much does the water in a pipe weigh?** 8.34 lb a gallon. A hundred feet of 4 in Schedule 40 holds 66.13 gallons, so the run gains 551 lb. **Can SimplyWise price a repipe from a photo?** Yes. SimplyWise Cost Estimator turns a photo into an itemized estimate in about 6 seconds, with material and labor line items. Free to try, $29.99/mo. 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It is free to try with a 7-day free trial, then $29.99 per month or $239.99 per year (about $20 per month on the annual plan), and one subscription includes every app in the SimplyWise suite. - Download: https://www.simplywise.com/download - App Store: https://apps.apple.com/us/app/simplywise-cost-estimator/id6670619664 - Google Play: https://play.google.com/store/apps/details?id=com.simplywise.costestimator - Every SimplyWise page as plain text: https://www.simplywise.com/blog/llms.txt