Hydraulic quick release coupling sizes

Selecting the correct size for your hydraulic quick-release coupling is essential to ensure system efficiency, prevent pressure drops, and maintain operator safety. While ISO standards provide guidelines, navigating the vast array of available dimensions can be challenging.

This guide provides a comprehensive overview of the standard sizes available at Faster, helping you identify the right series based on flow capacity, application, and system requirements.

Product availability by size and series

To streamline your selection process, we have mapped our core product series against the available body sizes.
(Legend: ✓ = Available)

Still not sure which size to pick?

If you are uncertain about the shape, size, or series of the component you are looking at, use our visual tool to find the exact match in seconds.

Try the Hydraulic Quick Couplings Identificator.

Introduction to coupling sizes

Below is a detailed breakdown of the different dimensions, designed to guide you toward the ideal component for your machinery.

1/8” Quick release coupling

When space is extremely limited and the application requires very low flow rates, such as in diagnostic testing equipment or micro-hydraulics, the 1/8” quick release coupling is the standard choice. Its compact design ensures reliable connections in the tightest engine compartments.

1/4" Hydraulic quick couplings

Designed for small hand tools, light jacking systems, and applications with flow rates up to 12 LPM, our 1/4" hydraulic quick couplings offer an optimal balance between compactness and pressure resistance.

1/2" Hydraulic quick couplings

Widely recognized as the global standard (meeting ISO 16028 and ISO 7241 requirements), 1/2" hydraulic quick couplings are the go-to solution for standard tractors, skid steers, and medium-sized earthmoving machinery, managing flow rates between 30 and 60 LPM.

5/8” Hydraulic quick couplings

For applications requiring a specific connection just above the standard half-inch mark, 5/8” hydraulic quick couplings provide the necessary flow upgrade. They are highly valued in heavy-duty machinery where specific manufacturer tolerances apply.

3/4" Hydraulic quick couplings

When dealing with large excavators and high-flow attachments (60–110 LPM), preventing oil overheating is critical. Using 3/4" hydraulic quick couplings allows the system to maintain optimal operating temperatures during intensive hydraulic tasks.

1" Hydraulic quick couplings

In the heavy machinery and massive earthmoving sectors, main return lines and high-pressure supply lines demand maximum reliability. Our 1" hydraulic quick couplings are engineered to withstand extreme pressures and continuous operations.

1-1/4" Hydraulic quick couplings

Used primarily in industrial and off-shore applications, 1-1/4" hydraulic quick couplings manage ultra-high flow rates, ensuring near-zero pressure drops in massive hydraulic circuits.

1-1/2" Hydraulic quick couplings

For heavy industry, oil & gas, and large-scale mining equipment, 1-1/2" hydraulic quick couplings provide the massive fluid transfer capacity required for critical, large-scale operations.

2" Hydraulic quick couplings

Representing the maximum size in our standard catalog, 2" hydraulic quick couplings are the ultimate solution for main power lines, large pumping stations, and applications where maximum fluid displacement is mandatory.

FAQ: sizing and measurement

How do I know what size coupler I need?

To determine the correct quick-release coupling size, focus on system compatibility and flow capacity rather than just physical dimensions.

1. Identify the "Interchange" (The Family)

Size is irrelevant if the shapes don't match. Before measuring, look at the Male Plug to find its family:

• Poppet/Agricultural: Pointed valve. Most older tractors use proprietary series designed decades before ISO standards.
• Flat Face: Flush ends. Standard on modern construction equipment to prevent spills.
• Threaded: If the sleeve screws on, it’s a high-pressure/high-vibration series (often proprietary).

2. Match Body Size to Flow Rate (GPM/LPM)

The "Body Size" (e.g., 1/2") refers to the internal flow capacity, not the physical width of the coupling. You must choose a size based on your machine’s output in Gallons Per Minute (GPM) or Liters Per Minute (LPM) to avoid overheating the oil.

3. Select the Port Thread

The "back end" must match your hose. A single Body Size (like 1/2") is often available with multiple thread options (e.g., 1/2" NPT, 3/4" JIC, or 22mm Metric).
Check the seal: Does your hose end have a tapered thread, a flared tip, or an O-ring?

How to measure hydraulic coupling size?

To measure a hydraulic quick-release coupling — whether it complies with an ISO standard or it is a proprietary design — you must identify the Body Size and the Interface Profile.
Many proprietary series were established decades before ISO standards (like ISO 7241 or 16028) were even written. These designs remain in use today not just for performance reasons, but because of their massive "installed base" on legacy equipment.

1. Measure the Male Plug (Nipple)

The most reliable way to identify a coupling is to measure the male half using a caliper. The critical dimensions are:

• Outside Diameter (O.D.): Measure the widest part of the probe that inserts into the female half.
• Probe Length: Measure the length of the "nose" from the tip to the base where it begins to widen.
• Profile Shape: Note if the valve is Flat Face, Poppet (pointed), or Ball (round).

Note: Many proprietary series share similar O.D. measurements with ISO standards but differ by just 1 mm to 2 mm in length or shape.

2. Determine the Body Size (Dash Size)

Hydraulic sizes are categorized by "Nominal Diameter" (the internal flow path). While O.D. varies by brand, the measurements generally fall into these standard "Dash" increments:

3. Check the Connection Type

Determine whether the coupling utilizes a push-pull mechanism, a screw-to-connect system, or standard locking sleeves.

4. Port Thread Identification

After identifying the body (quick-release end), measure the threaded end that connects to the hose. You must measure the Thread O.D. and the Pitch (TPI or mm) to determine if it is NPT, BSPP, Metric, or JIC.

5. Pro-Tip: Check the "Hex"

On proprietary and legacy couplings, manufacturers often stamp the part number or series name on the "hex" (the flat part where you put a wrench). If you find a code, you can skip the measurements and search that number directly on our website to find the exact match.