Reading a Motorcycle Oil Filter Number (HF vs HFA)
Reviewed by CrankDex editorial
Motorcycle filters are usually sold under a short code like HF204 or HFA1616. Here's what the letters mean, and why the number, not just the letters, is what determines whether a filter actually fits.
Walk into any powersports parts counter or search a fitment tool, and motorcycle filters show up labeled with codes like HF204, HFA1616, or HFF1012. This numbering convention, popularized by Hiflofiltro and referenced across the aftermarket, is a quick way to identify filter type, but it's the full number, not just the letters, that tells you whether a given filter fits your bike.
What the letters mean
In the Hiflofiltro-style system, the letter prefix identifies the category of filter. HF generally denotes an oil filter. HFA denotes a paper air filter. HFF denotes a foam air filter. Other manufacturers use their own prefixes, but the underlying idea is the same across the aftermarket: the letters narrow down what kind of filter you're looking at before you even get to the numbers.
Why the number is what actually matters
Two oil filters can look nearly identical, similar diameter, similar thread, and still be built differently on the inside: different bypass valve pressure, different amounts of filter media, or a different anti-drain-back valve setup, all matched to a specific engine's oil pump and oil system. That's why "close enough" isn't a safe way to shop for an oil filter. The number is the manufacturer's way of saying "this exact filter was engineered for this application," and matching it (or a verified cross-reference) is what actually gets you correct fit and function, not just a filter that threads onto the engine.
Cross-referencing between brands
You don't have to buy the exact same brand as what came on the bike. Filter manufacturers publish cross-reference charts that map their own numbers to OEM part numbers and to equivalent numbers from other aftermarket brands. If you know one number, a cross-reference lookup can usually get you to the same filter under a different label, which is useful if your preferred brand or local store carries something different from what's listed in the manual.
Where to find your bike's number
The most reliable sources are your owner's manual, a fitment lookup tool for your exact year, make, and model, or the old filter itself if the part number is still legible on the case. Guessing from a filter that "looks about right" on the shelf skips the one step that actually confirms fit, so when in doubt, look the number up rather than eyeballing it.
Browse Hiflofiltro oil filters on Amazon (we may earn a commission, at no extra cost to you), or look up your bike to confirm the exact filter number before you buy.
Frequently asked
What's the difference between HF and HFA on a filter box?
The letters describe the filter type, not the fitment on their own. HF generally marks oil filters, HFA marks paper air filters, and HFF marks foam air filters, all part of the same numbering family used by Hiflofiltro and referenced by other brands. The number after the letters is what narrows it down to a specific application.
Will any oil filter with the right thread fit my bike?
Thread size and gasket diameter matter, but they're not the whole story. Filters also differ in internal bypass pressure, media area, and physical length, all tuned to a given engine's oil system. Matching the filter number (or a verified cross-reference to it) is the reliable way to get a filter that fits and flows correctly, rather than just one that threads on.
Can I cross-reference a filter number to a different brand?
Yes, this is common practice. Most major filter brands publish cross-reference charts mapping their part numbers to OEM numbers and to other aftermarket brands' numbers. If you have a filter number from one brand, a cross-reference lookup (or your fitment tool) can usually find the equivalent from another.
Where do I find my bike's exact filter number?
Your owner's manual usually lists it, or you can look up your specific year, make, and model in a fitment tool. The old filter, if it's still installed, often has its own part number printed on the case as well, which is a reliable starting point if you can read it.
Need your machine's exact battery? Look up your oil filter →