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How to Measure Spa Filters

Measuring a hot tub filter is easy. 

Measure the length, then the width or outer diameter. 

Finally measure the diameter of the inner hole if there is one, or note the features of the top and bottom of the filter.  Does it have a top handle or threaded bottom? Are the threads fine (mpt) or course (sae)?

Sometimes the top has a handle and the bottom may have a threaded connector.

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Filter Model Number - Enter into Search Box Above
If you have a filter model number, you can just search by model.  It is always a good idea to measure your existing filter to be sure you get the correct replacement filter.

measure-the-old-filter.jpgOne of the biggest problems when ordering a replacement filter that has a threaded connector on the bottom of the filter is that the thread size may be incorrect. 

There are two main types of threads on the bottom of spa filters. 

A course thread (or SAE thread) and a fine thread (or MPT thread).  The course thread only has a few, larger spirals while the fine thread has many more thinner and closer together spirals. 

Search by filter part number in the search box at the top of the page, or let us do the work for you.


When in doubt, send us a picture along with your measurements at to be sure. 

We'll send you your filter options by return email - fast!  - even on weekends.

Then there is also either a male thread that portrudes from the bottom of the filter, or a female thread that goes up inside the filter. 

Most hot tub filters that are threaded have the male type connectors. 

Again, if you have any question about the thread type on your filter, just send us an email with a photo of your filter.

Shop for hot tub filters online here.

hottuboutpost filter measure

See our spa filters section or complete the form below for assistance in finding a replacement filter cartridge for your hot tub.