When it comes to construction, plumbing, automotive repairs, HVAC systems, or even DIY furniture projects, tubes are everywhere. They carry liquids, gases, and sometimes even act as structural components. But with so many diameters, thicknesses, and standards, choosing the right tube size can feel confusing. That’s where a tube size chart comes in handy.
In this guide, we’ll break down everything you need to know about tube sizing, including outer diameter (OD), inner diameter (ID), wall thickness, and industry standards. We’ll also include easy-to-read charts that you can use as a reference for your projects.
Why Tube Size Matters
Using the wrong tube size can cause leaks, pressure failures, or poor structural support. For example:
In plumbing, undersized tubes can reduce water flow.
In HVAC, oversized tubes may reduce system efficiency.
In automotive repairs, the wrong tube size can lead to unsafe connections.
That’s why professionals rely on tube size charts — they ensure the right fit, safety, and performance.
Key Terms You Need to Know
Before diving into the chart, let’s clear up some basics:
OD (Outer Diameter): The total width of the tube measured from the outside edges.
ID (Inner Diameter): The hollow inside width of the tube.
Wall Thickness: The thickness of the tube wall, which impacts strength and flow capacity.
Gauge: In some industries, wall thickness is represented in “gauge.” A higher gauge means thinner walls.
Schedule (SCH): A common way of denoting tube thickness in plumbing (like SCH 40 or SCH 80).
Standard Tube Sizes (Inches and Millimeters)
The most common tube measurements come in inch-based (imperial) and millimeter-based (metric) standards. Here’s a handy chart:
Tube Size Chart (OD, ID, and Wall Thickness)
| Tube OD (Inches) | Tube OD (mm) | Common Wall Thickness (in) | Wall Thickness (mm) | Approx. ID (in) | Approx. ID (mm) |
|---|---|---|---|---|---|
| 1/4″ | 6.35 mm | 0.035″ | 0.89 mm | 0.18″ | 4.57 mm |
| 3/8″ | 9.53 mm | 0.035″ | 0.89 mm | 0.31″ | 7.87 mm |
| 1/2″ | 12.7 mm | 0.049″ | 1.24 mm | 0.40″ | 10.2 mm |
| 5/8″ | 15.88 mm | 0.049″ | 1.24 mm | 0.53″ | 13.5 mm |
| 3/4″ | 19.05 mm | 0.065″ | 1.65 mm | 0.62″ | 15.7 mm |
| 1″ | 25.4 mm | 0.065″ | 1.65 mm | 0.87″ | 22.1 mm |
| 1-1/4″ | 31.75 mm | 0.083″ | 2.11 mm | 1.08″ | 27.4 mm |
| 1-1/2″ | 38.1 mm | 0.083″ | 2.11 mm | 1.33″ | 33.8 mm |
| 2″ | 50.8 mm | 0.120″ | 3.05 mm | 1.76″ | 44.7 mm |
👉 This chart helps quickly identify the inner diameter based on outer diameter and wall thickness.
Standard Tube Sizes PDF:
Download our Standard Tube Sizes PDF for quick and reliable reference. This guide includes outer diameter (OD), inner diameter (ID), wall thickness, and conversion charts in both metric and imperial units. Perfect for engineers, plumbers, mechanics, and DIY enthusiasts, this PDF ensures accurate tube selection for plumbing, construction, automotive, and industrial applications.
Tube_Size_Chart Pdf
Also Read:
Tube Schedules (Thickness Ratings)
In plumbing and industrial applications, tubes are often categorized by schedule numbers. A higher schedule means thicker walls, which handle higher pressure.
Tube Schedule Chart (Example for 1″ OD Tube)
| Schedule (SCH) | Wall Thickness (in) | Wall Thickness (mm) | Approx. ID (in) | Approx. ID (mm) |
|---|---|---|---|---|
| SCH 10 | 0.065″ | 1.65 mm | 0.87″ | 22.1 mm |
| SCH 40 | 0.133″ | 3.38 mm | 0.73″ | 18.5 mm |
| SCH 80 | 0.179″ | 4.55 mm | 0.64″ | 16.3 mm |
| SCH 160 | 0.250″ | 6.35 mm | 0.50″ | 12.7 mm |
👉 Use schedule charts when dealing with pressure-rated piping.
Tube Size Conversion (Metric ↔ Imperial)
Sometimes, you may need to convert between metric and imperial systems. Here’s a quick chart for common conversions:
| Imperial Size | Metric Equivalent | Imperial Size | Metric Equivalent |
|---|---|---|---|
| 1/8″ | 3.2 mm | 1-1/4″ | 31.8 mm |
| 1/4″ | 6.4 mm | 1-1/2″ | 38.1 mm |
| 3/8″ | 9.5 mm | 2″ | 50.8 mm |
| 1/2″ | 12.7 mm | 3″ | 76.2 mm |
| 3/4″ | 19.1 mm | 4″ | 101.6 mm |
| 1″ | 25.4 mm | 6″ | 152.4 mm |
👉 This chart is useful when working with international suppliers.
Applications of Tube Sizes
Tube sizing isn’t just numbers on a chart — it directly affects performance.
Plumbing:
Copper, PVC, and PEX tubes are used for water supply.
Wall thickness ensures durability and leak-free connections.
Automotive:
Fuel lines, brake lines, and exhaust systems depend on precise tube sizes.
Incorrect sizing may cause dangerous leaks.
Construction:
Structural tubing supports weight and resists bending.
OD and wall thickness determine load capacity.
HVAC Systems:
Air conditioning lines require accurate sizing to maintain pressure.
DIY & Furniture:
Steel or aluminum tubes are used for frames, shelves, and custom builds.
Tips for Choosing the Right Tube Size
Check Standards: Always use ASTM, ISO, or ANSI sizing standards.
Consider Pressure Ratings: Higher pressure = thicker wall (higher schedule).
Allow for Flow Capacity: Don’t undersize in plumbing or HVAC.
Account for Fittings: ID must match with the fittings you plan to use.
Measure Twice: Always double-check OD and ID before cutting or ordering.
Also Read:
Common Tube Materials and Their Sizes
While size is crucial, the material of the tube also plays a big role in performance and durability. Each material has its own common size ranges and applications:
Copper Tubes: Widely used in plumbing and HVAC due to corrosion resistance. Available in sizes from 1/8″ to 6″.
Steel Tubes: Common in construction and automotive, providing high strength. Often sized from 1/2″ to 24″.
Stainless Steel Tubes: Used where hygiene or chemical resistance is important, such as food, medical, or marine industries.
PVC/Plastic Tubes: Lightweight and cost-effective, often used in household plumbing and irrigation.
Aluminum Tubes: Popular in lightweight structures, bicycles, and furniture due to strength-to-weight ratio.
Understanding both the size and material ensures the tube meets pressure, temperature, and environmental demands.
Tube Maintenance and Safety Tips
Even if you choose the correct size, improper maintenance can shorten tube life. Here are a few expert tips:
Inspect Regularly: Look for leaks, dents, or corrosion, especially in metal tubes exposed to moisture.
Clean Interior: For fluid-carrying tubes, ensure no blockages or mineral buildup restricts flow.
Use Proper Fittings: Always match fittings with correct OD/ID to avoid weak connections.
Avoid Over-Bending: Tubes have bending limits—exceeding them may cause cracks or collapse.
Replace on Time: For high-pressure systems, replace tubes before the manufacturer’s recommended lifespan.
By combining correct sizing with proper care, you maximize tube efficiency, safety, and longevity.
Final Thoughts
A tube size chart is more than just numbers — it’s a practical tool for engineers, mechanics, plumbers, and DIY enthusiasts. Whether you’re working with plumbing pipes, automotive lines, or structural tubes, knowing the correct dimensions ensures safety, efficiency, and durability.
By using the charts provided above, you can quickly identify the right tube size for your next project. Bookmark this guide, and you will never struggle with tube sizing again.
FAQs:
What is the difference between tube OD and ID?
Tube OD (Outer Diameter) measures the width of the tube from the outside edges, while ID (Inner Diameter) measures the hollow space inside. OD is critical for fittings, while ID determines flow capacity. For example, a 1-inch OD tube with a thick wall will have a smaller ID, affecting how much liquid or gas can pass through.
Why is wall thickness important in tube sizing?
Wall thickness determines the strength, pressure capacity, and durability of a tube. Thicker walls can handle higher pressures and provide better structural support, while thinner walls allow for better flow but less strength. In plumbing, automotive, or HVAC systems, choosing the right wall thickness ensures both safety and performance, making it essential to check thickness in charts before buying.
What does “Schedule” mean in tube sizing?
“Schedule” (SCH) refers to standardized wall thickness categories in tubes and pipes, such as SCH 40, SCH 80, or SCH 160. A higher schedule means a thicker wall, which supports higher pressure. For example, a 1-inch tube in SCH 40 will have thinner walls than SCH 80, making schedule selection vital for plumbing, industrial, and pressure-based applications.
How do I convert tube sizes between metric and imperial units?
Tube sizes often come in both metric (mm) and imperial (inches) standards. For quick conversion, 1 inch equals 25.4 mm. Charts make it easy to find equivalents, such as 1/2″ ≈ 12.7 mm or 3/4″ ≈ 19.1 mm. Always use conversion tables when sourcing internationally, since a mismatch can cause fitting issues and system inefficiency in construction or mechanical projects.
Which tube materials are most common in construction and plumbing?
The most common tube materials include copper, steel, stainless steel, PVC, and aluminum. Copper is used in plumbing and HVAC due to corrosion resistance. Steel and stainless steel provide strength for construction and automotive uses. PVC is lightweight and affordable, ideal for household plumbing. Aluminum is strong yet light, often used in furniture, bicycles, and structural applications.
How do I choose the right tube size for my project?
To select the right tube size, consider three key factors: pressure capacity, flow requirements, and fitting compatibility. For plumbing, ensure ID allows sufficient water flow. For HVAC, correct sizing maintains efficiency. In structural projects, OD and wall thickness determine strength. Always check standard charts, follow ASTM/ISO guidelines, and measure twice before ordering or cutting tubes.