Two per component. Every block, radiator and pump/reservoir has an inlet and an outlet, and each one takes a compression fitting. A basic CPU loop needs 6. Add a GPU block and it is 8.
Count your components
Write down every part the coolant flows through, then give each one two fittings.
| CPU block | 2 |
| GPU block | 2 |
| Each radiator | 2 |
| Pump and reservoir combo | 2 |
| Separate pump and separate reservoir | 2 each |
Common loops
Not sure what your loop needs? Our cost guide walks through a full parts list: AIO or Custom Loop? What Water Cooling Costs.
Pick fittings that match your tubing
Compression fittings are sized to the tubing, so choose the tube first. For soft tubing we recommend 16/10mm (3/8" x 5/8"): it is the most flexible common size and the least prone to kinking. Building with hard tube? Use hard tube fittings that match the tube.
Alphacool HF six pack
Six 16/10mm compression fittings for $22.00, enough for a CPU loop.
Shop the six packPrices checked September 2026. Tubing: ModMyMods 16/10mm clear, $1.25 a foot (sold by the foot).
Extras that make the build easier
These thread in between a port and its compression fitting, so they do not change your count.
Tight corner?
Rotary adapters turn the fitting so the tube runs where you need it.
90 degree · 45 degreePull parts without draining?
Quick disconnects let you remove a radiator or graphics card with the loop still full.
Shop quick disconnectsWant us to count it for you?
Send us your parts list and we will tell you exactly what fittings to order.
