Tube Size Calculator
Enter the outside diameter, wall thickness and length of the tube and choose the material. The calculator gives the inside diameter, weight per metre, total weight and how much liquid the tube holds.
- ID from OD and wall
- Weight per metre
- Internal volume
All sizes in millimetres, length in metres.
Round tube is sold by outside diameter and wall thickness. The inside diameter is the outside diameter minus two walls. Weight depends on the metal in the wall: a 25 mm steel tube with a 2 mm wall weighs about 1.13 kg per metre.
Steel tube weight chart
Mild steel, 7.85 g/cm³. Search for a size.
| OD × wall (mm) | ID (mm) | kg per metre |
|---|---|---|
| 20 × 1.5 | 17 | 0.684 |
| 25 × 2 | 21 | 1.134 |
| 30 × 2 | 26 | 1.381 |
| 40 × 2 | 36 | 1.874 |
| 50 × 3 | 44 | 3.477 |
| 60.3 × 3.2 | 53.9 | 4.506 |
For aluminium multiply by 0.34. For stainless multiply by 1.01.
Wall thickness and weight
25 mm tube. Slide the wall thickness.
The end view on the left shows the hole getting smaller as the wall gets thicker.
How to work out tube weight
Mean diameter × wall. Step through it.
Inside diameter
OD − 2 × wall.
Steel shortcut: kg per metre = (OD − wall) × wall × 0.02466.
Steel, aluminium or copper
Tube materials. Compare them.
Strong and cheap.
Light and rust free.
Plumbing and heat transfer.
Stainless tube resists rust without paint but is harder to cut and weld.
Before ordering
Tube checks. Tick each item.
Tick each item as you go.
Allow a few millimetres per cut for the saw blade when working out lengths.
What you get
Tube figures. Each tile explains one result.
OD minus two walls.
In kg.
For your length.
Litres per metre.
Metal in mm².
Volume is useful for heating loops, hydraulic lines and working out how much liquid fills a pipe run.
Frequently Asked Questions
No question matches that search.
How do I find the inside diameter of a tube?
Outside diameter minus twice the wall thickness.
How much does steel tube weigh per metre?
(OD − wall) × wall × 0.02466 kg, in mm.
How much does a 25 × 2 mm steel tube weigh?
About 1.13 kg per metre.
How much water does a tube hold?
π × (ID ÷ 2)² ÷ 1,000 litres per metre, with ID in mm.
Is tube the same as pipe?
Tube is sized by outside diameter; pipe by a nominal bore.
How much lighter is aluminium tube?
About a third of the weight of steel.
What is wall gauge?
An older way to state wall thickness. 16 gauge is about 1.6 mm.
Know your tube before you cut
Enter the size and material to get the bore, weight and volume. Order the right amount and know what you are lifting.
More size calculators
Each one has its own calculator, worked examples and answers to common questions.