I have ordered several faucet handles but every one has been too large, or the wrong shape (square). Home Depot and Lowe's have handles but all too large or the wrong shape. Universal Outdoor Faucet Handle - too large/wrong shape. House was built about 12 years ago. Is this faucet really that rare? I would appreciate your expert advice, this has become frustrating.
I know this thread is old but I found it because I'm having the same issue. I wanted to share what I found for a solution. Hope this helps anyone else out there.
There are a multitude of manufacturers of hose faucets, both foreign and domestic. The handle spline type and stem size is not standard, there are as many sizes and spline counts as there are manufacturers (hundreds, thousands?). As suggested by @WarLoki, try a good local hardware and/or plumbing shop and you may find a variety of a few different ones. You should also begin planning for the (probably) inevitable replacement of the faucet.
Or get one of these crappy universal handles that uses set-screws:
Years ago, most hose faucets/bibs/spigots/valves were manufactured in the good ole' US of A by a few long standing companies, you could get replacements parts for those. Sadly most people do not want to spend a couple bucks more for better quality so we are left with Chinese junk that cannot be repaired, just like one day we won't have any good Mom-and-Pop hardware and plumbing shops because everyone goes to Home Depot and Lowes for poor service, self checkout, and Chinese junk. Sorry to rant... good luck.
In my experience, the issue is usually the stem and not the handle; the stem is usually brass and the knurls get rounded off once the handle gets loose. So replacing the handle doesn't help much. Sometimes you can find a replacement stem, but that's probably as costly as just replacing the whole thing.
For a reasonable temporary repair, I'll epoxy the handle onto the stem, and when that breaks just replace the entire spigot ($20) rather than spend hours trying to match parts.
I had the same problem, all the available replacement handles were too big. I went to a real plumbing supply store, Brother's Plumbing in Sacramento. They measured the spline size, said it was a "1" and sold me a 287-T Tee Handle MFG. by Thriftco Plumbing. It didn't slide on that well, but after I gave a couple of whacks with a rubber mallet and secured it with a #8-32 x 3/4" brass screw, it stayed on and works fine. All my exterior hose bibs were installed 25 years ago, are like this, manufactured in the Philippines, and that is why it probably is tough to find a fit.