Tool
Size Finder
If the code is unreadable, work from the dimensions. Enter your calliper readings and matching products are listed instantly.
Start typing the dimensions — results appear instantly. If you only have two, leave the third blank.
| Product | Size (mm) | Material | Hardness | Action | |
|---|---|---|---|---|---|
How to measure
Four steps to an accurate measurement
Wrong measurements are the most common reason for the wrong part. It takes three minutes.
- 1
Place the part on a clean surface
Wipe oil and dirt off the seal before measuring. A measurement taken from a deformed or crushed part will point you to the next size up or down; if possible, measure an unused sample from the spares box.
- 2
Measure the inner diameter
Measure the inner opening of the part with the inside jaws of the calliper. This is the diameter the rod or piston passes through and the most decisive dimension for the search.
- 3
Take the outer diameter and height
The outer diameter is the diameter of the housing the seal sits in. The height is the seal's thickness along the axis. For O-rings, measure the cross-section instead of the height; the outer diameter is calculated from the inner diameter and cross-section.
- 4
Enter the three numbers in the tool
If you only have two, leave the third blank; the tool will still list matches. If nothing comes up, widen the tolerance by one step.
Sizing logic
Which dimensions for which product
O-rings and X-rings
Defined by two dimensions: inner diameter and cross-section. The outer diameter follows from these (inner diameter + 2 × cross-section), so there is no need to measure it. Enter the cross-section in the “height / cross-section” field.
Seals, guide rings and bushings
Three dimensions are needed: inner diameter, outer diameter and height. On oil seals these are often printed on the part; if legible, you can enter them directly.
If you know the product group, choosing it in the filter narrows the results considerably. You can also search by a word in the product name, such as “U-cup”, “buffer” or “oil seal”. For catalogue products with technical drawings see the product catalogue, and for all the O-ring sizes we supply see the O-ring size chart.
Frequently Asked Questions
Common questions
What does the size finder do?
If you don't know the code of a removed seal, O-ring or guide element, it lets you find matching products in our stock by entering the dimensions you measured with a calliper. It is the fastest way when the code is unreadable.
Which dimensions do I need to enter?
For seals and guide elements: inner diameter, outer diameter and height. For O-rings, inner diameter and cross-section are enough; the outer diameter is calculated from them. You can also search with only two dimensions.
What does tolerance mean?
A calliper measurement taken in the field can be half a millimetre out, and a used part is slightly deformed. The tolerance sets how many millimetres above and below your measurement records are also listed. The default ±0.5 mm is enough in most cases.
What if my size doesn't come up?
The tool first widens the tolerance step by step and suggests the closest sizes. If there is still no suitable result, send us the dimensions: we can also supply sizes that are not on the list.
Are the listed products in stock?
The list is generated from our current product records, but for real-time stock you need to request a quote. When you send us the size, we reply with the lead time.
Couldn't find your size?
Send us a photo of the part and its dimensions and we'll look at it together. We can also supply sizes that are not on the list.