UGG Size Chart

Separate the lining from the length

UGG boots are sized by foot length but feel like they are sized by volume, and the difference is the sheepskin. The Classic boots are built with a thick Twinface sheepskin upper and a sheepskin lining and insole, so a new pair feels snug across the top of the foot even when the length is correct. That initial snugness is expected: the lining compresses and molds to your foot within a few wears, and the boot settles into a comfortable hold. Retailer fit surveys show roughly three quarters of wearers rating the Classic styles true to size, which suggests many of the “runs small” reports are really the first-wear lining feel.

The practical consequence is to judge length, not tightness. Measure both feet standing, heel to toe, in centimeters, and use the longer foot. Compare that with the chart for the exact model. If your toes sit flat inside the footbed with a little room at the front and the heel stays put when you walk, the length is right even if the top of the boot feels firm.

Whole sizes: how to round a half size

Many UGG styles, including the Classic II boots, are sold in whole sizes only, which forces half-size wearers to pick a direction. The prevailing retailer guidance for the Classic II is to order the next size down when you are between sizes: the lining packs down, so a boot that starts slightly snug ends up shaped to your foot, while a boot that starts loose only gets looser as the lining settles. A minority of guides argue the opposite, that a lined boot should never start tight, so treat the rounding direction as a trade-off rather than a rule.

Round down when your longer foot sits comfortably within the smaller size’s measurement range and you wear thin socks or none.

Choose the larger whole size when you plan to wear thick socks, when your feet swell noticeably over the course of a day, or when your measurement lands near the top of the smaller size’s range. If you can, order both whole sizes and walk in each on a clean surface; heel lift while walking is the deciding signal in a lined boot.

Boots, slippers, and suede styles sit differently

One brand does not mean one fit, and UGG’s categories show why. The Tasman II slipper runs true to size with the same snug-at-first lining behavior, but because slippers are often worn barefoot, the sizing decision starts with socks: fit for how you will actually wear them, and expect a mold-to-foot break-in either way. Suede styles such as the Neumel family are a different animal: they run true to size with a more relaxed toe box, which makes them the friendlier option for wider feet.

Platform and weather-treated versions change the outside of the boot more than the length, but a coated or reinforced upper can feel stiffer through the first wears, so allow a longer break-in on those listings. Re-check the chart per model: a Mini and a Tall in the same numeric size should agree on length, but the shaft height and opening deserve their own look on the product page before you order.

The Australian label confusion, explained

The name itself causes mix-ups. The sheepskin boot style originated in Australian and New Zealand surf culture, and in Australia “ugg boot” is used as a generic term for sheepskin boots made by many local companies. The UGG brand on ugg.com, by contrast, is a US label, and its size charts are US-first, showing UK, EU, Japanese, and Chinese equivalents alongside. Neither arrangement is wrong, but they collide at the checkout: locally made Australian ugg boots may carry Australian or UK size labels that do not equal the US size you normally wear. If you buy from an Australian retailer, check which scale the listing uses before converting anything, then find the stated foot length in centimeters and match it to your own measurement; that figure is the one that travels across every labeling system without ambiguity.

Kids’ UGGs: measure, then add growth room

Kids’ UGG styles, including the Tasman II and the Classic boots, come in toddler, little kid, and big kid ranges, and the brand’s kids’ chart is its own table; do not convert an adult size down to fit a child. Measure the child’s longer foot while standing and leave the growth allowance the chart or retailer recommends. That allowance still applies to lined boots, because the lining molds to the foot while the shell length stays fixed.

The kids’ range is also a quiet option for adults with smaller feet: retailers commonly note that a big kid 5 fits roughly a women’s 7, and a big kid 4 roughly a women’s 6. If you go that route, check width as well as length, because kids’ lasts can be narrower, and a lined boot that is narrow will feel tight across the top even at the correct length.

A try-on sequence for a lined boot

1. Put on the socks you intend to wear (or none, for a barefoot slipper) and step into both boots.
2. Stand and check the length: toes flat, a little room at the front, heel not riding up.
3. Walk for a few minutes on a clean surface and expect firmness across the instep, not pressure on the toes or heel slip.
4. If the instep feels tight, give the pair a short indoor break-in period and watch for red marks or numbness, which mean the size itself is the problem.
5. Re-check the fit with the socks you will actually wear in winter if the pair is a winter purchase.

This independent page is not an official UGG chart. Confirm current model-specific measurements on the UGG site before ordering.