G1/4 Fittings and Tube Size Guide: OD12, OD14, OD16, Soft Tube

G1/4 is the thread, not the tube size

This is the mistake almost every new builder makes once.

G1/4 means the thread that screws into your water block, radiator, pump, reservoir, or distro plate. It does not mean every tube fits every fitting.

Most PC water-cooling parts use G1/4 ports. The tube side is a separate question.

Hard tube sizing

Hard tube fittings match the outside diameter of the tube.

Tube type  Fitting must match  Common use

---|

OD12 hard tube  12mm outside diameter  Compact builds, tighter bends

OD14 hard tube  14mm outside diameter  Balanced look and easier routing

OD16 hard tube  16mm outside diameter  Larger builds, heavier visual style

If you buy OD14 tube, use OD14 hard tube fittings. OD16 fittings will not seal OD14 tube properly. OD12 fittings will not accept OD14 tube.

Soft tube sizing

Soft tube fittings are usually listed with inner diameter and outer diameter.

For example:

· 10/13mm

· 10/16mm

· 13/19mm

The first number is the inner diameter. The second number is the outer diameter. Compression fittings need the correct outer diameter so the collar can clamp the tube.

Compression fittings vs barbs

Compression fittings look cleaner and hold the tube with a threaded collar. Barbs rely more on the tube gripping the barb, often with a clamp.

For most first-time builders, compression fittings are the calmer choice. They are not magic, but they make it easier to see whether the tube is seated correctly.

45-degree, 90-degree, rotary, and extenders

Straight fittings are not enough for most loops. You will usually need a few angled fittings to avoid ugly tube runs or tight bends.

Useful extras:

· 90-degree rotary fittings for GPU block terminals

· 45-degree fittings for cleaner radiator exits

· Male-to-male extenders for spacing

· Drain valve fitting for maintenance

· Stop plugs for unused ports

Do not plan the loop with only straight fittings unless the case layout is very simple.

Starter fitting checklist

For a single GPU loop, a practical starting point is:

· CPU block: 2 fittings

· GPU block: 2 fittings

· Radiator: 2 fittings

· Pump/reservoir: 2 fittings

· Drain port: 1 valve + adapter

· Extras: 2-4 angled fittings

That is usually 8 straight fittings plus a few angles. It is better to have two extra fittings than to stop a build because one tube run is impossible.

Suggested internal links:

· OD12 hard tube fittings

· OD14 hard tube fittings

· OD16 hard tube fittings

· soft tube fittings

· tube tools

· complete loop checklist

FAQ

Are all PC water-cooling fittings G1/4?

Most modern PC water-cooling parts use G1/4 threads, but always check the product page. Industrial and older parts can be different.

Can I mix OD14 tube with OD16 fittings?

No. Hard tube fittings must match the tube outside diameter.

Is hard tube better than soft tube?

Hard tube looks cleaner, but soft tube is easier to build and service. For a first loop, soft tube is often the safer choice.

How many fittings do I need?

Count two fittings per component, then add fittings for drain valves, sensors, angled routing, and spare ports.

Image alt suggestions:

· G1/4 fitting thread and hard tube outside diameter comparison

· OD12 OD14 OD16 hard tube fittings for custom water cooling

· Soft tube compression fitting size guide