AN Hose Size Chart
Master fluid lines with our AN Hose Size Chart and conversion guide.
AN Hose Size Chart
In the world of high-performance automotive engineering, aerospace, and marine applications, precision isn't just a goal, it’s a requirement. If you’ve ever peeked under the hood of a race car or inside a custom engine bay, you’ve likely seen vibrant blue and red fittings or sleek braided lines. These aren't just for show. They utilize the AN (Army-Navy) standard, a system designed during World War II to ensure that fluid transfer lines remained reliable under extreme pressure.
The Essential AN Hose Size Chart
When plumbing a fuel system, oil cooler, or braking system, referring to an AN Hose Size Chart is the only way to ensure your flow rates match your hardware requirements. Below is the standard conversion for the most common automotive sizes:
Here is the AN Hose Size Chart formatted in a clean Markdown code block. You can copy and paste this directly into any Markdown editor or documentation tool.
AN Hose Size Chart & Conversion
| AN Size | Tube OD (Inches) | Hose ID (Inches) | SAE Equivalent |
|---|---|---|---|
| -2 AN | 1/8" | 0.062" | 1/8" |
| -3 AN | 3/16" | 0.125" | 1/8" |
| -4 AN | 1/4" | 0.187" | 3/16" |
| -6 AN | 3/8" | 0.312" | 5/16" |
| -8 AN | 1/2" | 0.437" | 1/2" |
| -10 AN | 5/8" | 0.562" | 5/8" |
| -12 AN | 3/4" | 0.687" | 3/4" |
| -16 AN | 1" | 0.875" | 1" |
| -20 AN | 1-1/4" | 1.125" | 1-1/4" |
| -24 AN | 1-1/2" | 1.375" | 1-1/2" |
AN Hose Fitting Size Chart
While the hose determines your flow rate, the fitting determines your seal. In the AN system, the threads do not provide the seal; instead, they act as a mechanical press to join two 37-degree flared surfaces. Referencing an AN Hose Size Chart for fittings is the only way to ensure you are using the correct thread pitch and wrench size.
| AN Size | Thread Pitch (UNF) | Wrench Size |
|---|---|---|
| -3 AN | 3/8"-24 | 1/2" |
| -4 AN | 7/16"-20 | 9/16" |
| -6 AN | 9/16"-18 | 11/16" |
| -8 AN | 3/4"-16 | 7/8" |
| -10 AN | 7/8"-14 | 1" |
| -12 AN | 1-1/16"-12 | 1-1/4" |
| -16 AN | 1-5/16"-12 | 1-1/2" |
| -20 AN | 1-5/8"-12 | 2" |
What Exactly is "AN" Size?
The "AN" in AN size stands for Army-Navy. It was originally established by the U.S. Military to create a universal specification for hose fittings and fluid lines. The core logic of the system is based on the outside diameter (OD) of the metal tubing, measured in increments of 1/16th of an inch.
For example, a -4 AN (pronounced "dash four") represents a tube with an OD of $4/16"$, which simplifies to $1/4"$. While the AN number refers to the tube OD, the hose itself is designed to have an inside diameter (ID) that matches that specific flow capacity.
Why the Inside Diameter (ID) Matters
You might notice in the AN Hose Size Chart above that the hose ID is slightly smaller than the tube OD fraction. This is a critical distinction. Because high-performance hoses (like stainless steel braided PTFE or CPE rubber) have specific wall thicknesses, the interior "give" is what dictates your fluid volume.
If you are upgrading a fuel pump that pushes 400 liters per hour, using a -6 AN line when the manufacturer recommends a -8 AN line creates a bottleneck. This restriction leads to pressure drops and can cause "fuel starve," which, in a high-performance engine, often leads to catastrophic detonation.
Choosing the Right Material
Understanding the size is only half the battle; you must also match the hose material to the fluid.
- CPE (Chlorinated Polyethylene): The "standard" performance hose. It’s usually wrapped in stainless steel braid. Great for oil and coolant, but modern pump gas with high ethanol content (E85) can eventually permeate the rubber, leading to a "gas smell" in your garage.
- PTFE (Teflon): The gold standard. PTFE hoses are impervious to almost all chemicals, including E85 and brake fluid. They generally have a smaller OD for the same ID, making them easier to route in tight spaces.
- Nylon Braided: Often used for weight savings and a "stealth" black look. It’s easier on the hands during assembly than stainless steel.
Selecting the correct plumbing components is the difference between a reliable machine and a fire hazard. By keeping a printed AN Hose Size Chart in your toolbox, you eliminate the guesswork. Whether you are building a custom turbo setup or simply replacing a leaking transmission line, matching your AN sizes ensures your project performs exactly as engineered.
Product Compliance and Suitability
The statements contained in this guide are intended for general informational purposes only. Such statements do not constitute a product recommendation or representation as to the appropriateness, accuracy, completeness, correctness, or currentness of the information provided. Information provided in this guide does not replace the use by you of any manufacturer instructions, technical product manual, or other professional resource or adviser available to you. Always read, understand, and follow all manufacturer instructions. Portions of this article were generated in part by ChatGPT.
