Copper Pipe Dimensions Chart (Type K, L and M)
Choose the tube type and nominal size to read its outside and inside diameter, wall, weight and water volume, or print the full chart.
This copper pipe dimensions chart gives the size of Type K, Type L and Type M copper tube, the copper water tube that most people call copper pipe. Pick a type and a nominal size from 1/4 inch to 6 inches and the tool returns the outside diameter, the wall thickness, the inside diameter, the flow area, the weight per foot and the water volume per 100 feet. A second mode shows the full chart for one type, ready to print.
The dimensions follow ASTM B88. The tool runs in your browser, is free, and needs no sign-up, and nothing you enter is uploaded. Use it to check a fitting, estimate the weight of a run, or compare how much bore you lose when you move from Type M to Type K.
How to use the Copper Pipe Dimensions Chart
- Under What do you need?, choose Look up one tube size or Full chart for one type.
- Pick the Copper tube type: K, L or M. Type K has the thickest wall and Type M the thinnest.
- For a single size, pick the Nominal size in inches, from 1/4 to 6. Remember that the nominal size is 1/8 inch smaller than the real outside diameter, so a 3/4 inch tube measures 7/8 inch across.
- Read the result: outside diameter, wall thickness and inside diameter in inches and millimeters, the flow area, the weight in pounds per foot and kilograms per metre, and the water held per 100 feet or 100 metres.
- Check the small table under the result, which compares the wall and inside diameter of all three types for the size you chose. A dash means that type is not made in that size.
- For the full chart, choose a type and read the table of every size. Use Print / save as PDF to keep it.
- Open How it was calculated to see how the inside diameter, weight and water volume are worked out.
Preset buttons load typical cases, and Reset restores the starting example. Copy result copies the result lines with a link, and Copy link keeps your choices in the page address.
What are the dimensions of Type K, L and M copper pipe?
The outside diameter of copper water tube is the nominal size plus 1/8 inch for every size on this chart. Only the wall changes between types. For a 3/4 inch tube the outside diameter is 0.875 inch in all three types. Type K has a 0.065 inch wall and a 0.745 inch inside diameter, Type L has a 0.045 inch wall and a 0.785 inch inside diameter, and Type M has a 0.032 inch wall and a 0.811 inch inside diameter.
For a 1/2 inch tube the outside diameter is 0.625 inch. The walls are 0.049 inch for Type K, 0.040 inch for Type L and 0.028 inch for Type M, which gives inside diameters of 0.527, 0.545 and 0.569 inch. Type M is not made in the 1/4 and 5/8 inch sizes.
How is the inside diameter of copper tube found?
Subtract twice the wall from the outside diameter: ID = OD − 2 × wall. For Type L 1/2 inch, ID = 0.625 − 2 × 0.040 = 0.545 inch, which is 13.84 mm. The flow area is π ÷ 4 × ID², so 0.233 square inch.
How much does copper tube weigh per foot?
The weight comes from the metal area times the length times the density of copper, 0.323 pounds per cubic inch. For Type L 1/2 inch it is π ÷ 4 × (0.625² − 0.545²) × 12 × 0.323 = 0.285 pounds per foot. The result matches the weight printed in the ASTM B88 chart to within 0.6 percent across all sizes on this page. Type K 3/4 inch weighs 0.641 pounds per foot.
How much water does copper pipe hold?
The water held is the inside area times the length. Type L 1/2 inch holds about 1.21 US gallons per 100 feet (15.1 liters per 100 meters). Type L 2 inch holds about 16.1 gallons per 100 feet.
Sources
- ASTM B88 dimensions: Engineers Edge, Copper Tubing Size Chart ASTM B-88 (read October 2026)
- Inside diameters 1/4 to 3 inch cross-checked against Wikipedia, Copper tubing, which also gives the nominal-size rule (nominal = outside diameter − 1/8 inch)
- Copper density 0.323 lb/in³ (8.94 g/cm³); the computed weights are checked against the chart’s weight of tube only
Sizes above 6 inch are not listed here. Follow your supplier’s data sheet for the exact tube you buy.
Worked examples
| Input | Result |
|---|---|
| Type L, 1/2 in | OD 0.625 in, wall 0.040 in, ID 0.545 in, 0.285 lb/ft |
| Type K, 3/4 in | OD 0.875 in, wall 0.065 in, ID 0.745 in, 0.641 lb/ft |
| Type M, 1 in | OD 1.125 in, wall 0.035 in, ID 1.055 in, 0.465 lb/ft |
| Type L, 2 in | OD 2.125 in, wall 0.070 in, ID 1.985 in, 1.75 lb/ft |
Calculated by the tool above with these values.
Frequently asked questions
What is the difference between Type K, L and M copper pipe?
The difference is the wall thickness. For the same nominal size they have the same outside diameter, so they fit the same fittings. Type K is the thickest, Type L is in the middle and Type M is the thinnest, which makes M the lightest and gives it the largest bore. Check your plumbing code for which type is allowed for your job.
What is the actual diameter of 3/4 inch copper pipe?
The outside diameter is 0.875 inch (22.2 mm). The inside diameter is 0.745 inch for Type K, 0.785 inch for Type L and 0.811 inch for Type M.
Why is the outside diameter bigger than the nominal size?
Copper water tube is sold by nominal size, which is 1/8 inch smaller than the outside diameter. A 1/2 inch tube measures 5/8 inch (0.625 inch) across the outside.
How do I convert copper tube sizes to millimeters?
Multiply inches by 25.4. A 1/2 inch Type L tube has a 15.875 mm outside diameter, a 1.016 mm wall and a 13.843 mm inside diameter. The tool shows both units.
Is copper tubing the same as copper pipe?
The words are used for the same product. This chart covers ASTM B88 copper water tube, sized by nominal diameter and sold as Type K, L and M, which most sellers call copper pipe.
Can I use the results in commercial projects or client reports?
Yes, you can use them in quotes, design notes, reports and client projects without attribution. Check the tube you buy against its maker’s data, because the tool does not certify compliance with a code.
Related tools
- PVC Pipe Sizing Calculator and Chart: use it to choose a copper, PVC, PEX or steel size for a given water flow.
- Pipe Schedule Chart and Pipe Size Lookup: use it for steel, stainless and PVC pipe dimensions.
- Pipe Velocity Calculator: use it to check the water velocity in a copper tube.
- Pressure Drop Calculator: use it to find the friction loss in a copper line.
- Hazen Williams Calculator: use it to estimate friction loss in a water line.
- Flow Rate Calculator: use it to turn a pipe size and velocity into a flow rate.
- All pipe, pump and valve calculators: use it to browse every calculator on the site.