DIN Hydraulic Fittings Chart: Metric Light (L) and Heavy (S) Series
DIN metric tube fittings follow DIN 2353 and ISO 8434-1. They have metric threads and seal on a 24° cone.
Quick answer: A DIN metric fitting is named by its tube outside diameter in millimeters and its series, L (light) or S (heavy). The same tube size uses a different thread in each series. A 12 mm tube is M18x1.5 in the light series and M20x1.5 in the heavy series. Measure the thread and the tube, then match both in the charts below.
How a DIN 24° Cone Fitting Seals
The male end has a straight metric thread with a 24° cone machined inside it. The thread only clamps the joint. The seal is made in the cone, in one of two ways:
- Cutting ring. A nut pushes a hardened ring into the 24° cone. The ring bites into the tube and seals against the cone. This is the bite-type tube fitting.
- 24° cone with O-ring. A nose with an O-ring seats in the same 24° cone. Hose ends of this type are often labeled DKOL (light) or DKOS (heavy).
Because the thread does not seal, tape and thread sealant do nothing on a DIN fitting.
DIN Metric Fitting Size Charts
The size is the tube outside diameter. The number after the x in the thread is the pitch in millimeters.
| Size | Tube O.D. | Thread | Male thread O.D. |
|---|---|---|---|
| 6L | 6 mm (0.24″) | M12x1.5 | 12 mm (0.47″) |
| 8L | 8 mm (0.31″) | M14x1.5 | 14 mm (0.55″) |
| 10L | 10 mm (0.39″) | M16x1.5 | 16 mm (0.63″) |
| 12L | 12 mm (0.47″) | M18x1.5 | 18 mm (0.71″) |
| 15L | 15 mm (0.59″) | M22x1.5 | 22 mm (0.87″) |
| 18L | 18 mm (0.71″) | M26x1.5 | 26 mm (1.02″) |
| 22L | 22 mm (0.87″) | M30x2 | 30 mm (1.18″) |
| 28L | 28 mm (1.10″) | M36x2 | 36 mm (1.42″) |
| 35L | 35 mm (1.38″) | M45x2 | 45 mm (1.77″) |
| 42L | 42 mm (1.65″) | M52x2 | 52 mm (2.05″) |
| Size | Tube O.D. | Thread | Male thread O.D. |
|---|---|---|---|
| 6S | 6 mm (0.24″) | M14x1.5 | 14 mm (0.55″) |
| 8S | 8 mm (0.31″) | M16x1.5 | 16 mm (0.63″) |
| 10S | 10 mm (0.39″) | M18x1.5 | 18 mm (0.71″) |
| 12S | 12 mm (0.47″) | M20x1.5 | 20 mm (0.79″) |
| 14S | 14 mm (0.55″) | M22x1.5 | 22 mm (0.87″) |
| 16S | 16 mm (0.63″) | M24x1.5 | 24 mm (0.94″) |
| 20S | 20 mm (0.79″) | M30x2 | 30 mm (1.18″) |
| 25S | 25 mm (0.98″) | M36x2 | 36 mm (1.42″) |
| 30S | 30 mm (1.18″) | M42x2 | 42 mm (1.65″) |
| 38S | 38 mm (1.50″) | M52x2 | 52 mm (2.05″) |
Values are nominal, per DIN 2353 and ISO 8434-1. A male thread measures slightly under its nominal size. Verify against your part before ordering.
Light vs Heavy Series
The heavy series has a thicker wall and is built for higher pressure than the light series. Pressure ratings vary by size and by manufacturer, so check the rating of the part you are using.
The two series share several threads, so the thread alone does not tell you the size.
| Thread | Light series | Heavy series |
|---|---|---|
| M14x1.5 | 8L (8 mm tube) | 6S (6 mm tube) |
| M16x1.5 | 10L (10 mm tube) | 8S (8 mm tube) |
| M18x1.5 | 12L (12 mm tube) | 10S (10 mm tube) |
| M22x1.5 | 15L (15 mm tube) | 14S (14 mm tube) |
| M30x2 | 22L (22 mm tube) | 20S (20 mm tube) |
| M36x2 | 28L (28 mm tube) | 25S (25 mm tube) |
| M52x2 | 42L (42 mm tube) | 38S (38 mm tube) |
A third series, LL (extra light), covers small tube at low pressure.
How to Identify a DIN Metric Fitting in 3 Steps
- Read the nut. The size and series are often stamped on it, such as L15 or S20.
- Measure the thread. Use a caliper across the male thread, in millimeters, and a metric pitch gauge. DIN threads have a 1.5 mm pitch up to M26 and a 2 mm pitch from M30 up.
- Measure the tube. Measure the tube outside diameter, or the bore inside the male end where the tube sits. Match the thread and the tube in the charts above to get the size and series.
Check the cone. Look inside the male end for the 24° cone. On a seat angle gauge it reads 12°, because the gauge measures from the centerline.
Fittings That Look Like DIN
Several other fittings also use metric threads. The seat and the pitch tell them apart.
| Fitting | Thread | Seat | How to tell it from DIN |
|---|---|---|---|
| DIN 24° cone | Metric, 1.5 mm pitch, then 2 mm on the larger sizes | 24° cone inside the male end | This is the DIN fitting |
| French GAZ | Metric, 1.5 mm pitch on every size | 24° cone | Fine pitch on the large sizes, and tube sizes that are not whole millimeters |
| Komatsu 30° flare | Metric, 1.5 mm pitch on every size | 30° flare | No 24° cone inside the male end |
| Metric 60° cone (DIN 7631) | Metric | 60° cone | The seat measures 60°, not 24° |
Stopping a Leak at a Cutting Ring
A soft seal adds an elastomer seal to a cutting-ring joint. We stock SRWD soft seals for cutting rings for 24° DIN 2353 tube fittings.
Where You Find DIN Fittings
DIN metric fittings are the usual tube and hose connection on German and other European equipment. They turn up in North America on imported machines and attachments. When a DIN line has to meet a JIC, NPT or BSPP connection, the fix is an adapter with the correct end on each side.
We stock DIN light and heavy series fittings. Tell us the tube size, the series and what the other end connects to, and we will match it. See the hoses, fittings and adapters we stock and our fitting identification guide.
4 Mistakes to Avoid
- Going by the thread alone. M18x1.5 is a 12 mm tube in the light series and a 10 mm tube in the heavy series.
- Mixing the two series. A 12L nut is M18x1.5 and a 12S nut is M20x1.5. They do not fit the same body.
- Using tape or sealant. The thread does not seal. The joint seals in the 24° cone.
- Calling every metric thread DIN. French GAZ and Komatsu fittings also have metric threads.
Frequently Asked Questions
What is a DIN hydraulic fitting?
It is a metric fitting with a straight thread and a 24° cone, made to DIN 2353 and ISO 8434-1. It seals with a cutting ring on the tube or an O-ring in the cone.
What is the difference between L and S series DIN fittings?
L is the light series and S is the heavy series. The heavy series has a thicker wall for higher pressure, and it uses a different thread for the same tube size.
What does 12L mean on a fitting?
It means a 12 mm tube in the light series. That size has an M18x1.5 thread.
Are DIN fittings the same as metric fittings?
DIN is one family of metric fittings. Komatsu, French GAZ and metric 60° cone fittings also have metric threads, with different seats.
Is DIN 2353 the same as ISO 8434-1?
They describe the same 24° cone tube fitting. DIN 2353 is the German standard and ISO 8434-1 is the international one.
Can you ship DIN fittings outside the United States?
Yes. See worldwide shipping or request a quote with the destination country.
Not sure which fitting you have?
Send a photo next to a ruler or caliper and we will identify it.
Sources: DIN 2353 and ISO 8434-1 (24° cone tube fittings); DIN 7631 (metric 60° cone).
Last updated: November 14, 2026
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Hydraulic Hoses Near Me LLC in New Milford, CT is open 24/7. We stock Gates, Parker and Aeroquip hose and fittings and Adaptall adapters, and we ship worldwide. Mobile service covers CT, NY and MA. Call with your measurements or bring the old part and we will match it.