The Sand lizard is about 8 inches from nose to tail, with a robust build. The length of the tail makes up about half of the total length.

Sand lizards have two pale lines running along the dorso-lateral surface of the body. Between these stripes there is usually a camouflage pattern of black/dark brown and a lighter tan colour. Ocelli (white spots or short stripes running along the dorsal surface) are common, and usually run in a broken line down the very centre of the back, but it is not uncommon to have groups of upto 3 white spots running across the back, between the dorso-lateral stripes.

There is almost never a broken dark line running down the centre of the back, as often found with common lizards.

Throughout the mating season (mid-April to mid-May), the male develops brilliant green flanks. The combination of this green, with the mottled brown back is unmistakable. If you see a greenish lizard that is uniform in body colour, then you have probably seen a Common lizard.

Even out of the mating season, the male retains some green, although much diminished. The flank mottling of the male is finer with more black colouration than the female. Males sport a much larger head and deeper throat than the female of the species.

Sand lizards do exhibit some variety in colour and markings. Melanistic (black) and albino forms occur, but are exceptionally rare.

Sand lizards naturally form three metapopulations in Britain, often referred to as the three 'races':

• The Wealdon race, occupying Surrey, East Hampshire and West Sussex heathlands, and the Kentish coast.
• The Dorset race, occupying the Dorset, Devon and New Forest heaths,
• The Sefton race, which lives on the coastal dunes of West Lancashire, Wales and the Wirral.

Wealdon and Dorset animals are very similar in appearance, and the numerous re-introductions of Dorset animals into Surrey makes it effectively impossible to determine any difference between the two.

The Sefton race demonstrates some clear differences from their Southern kindred. Sefton animals often appear smaller and slimmer (particularly those occupying frontal dunes). Sefton males sport a lighter, lime-green coat when in mating moult, compared to the deeper bottle-green of Southern animals. Both male and female Sefton race lizards have wider and more prominent dorso-lateral stripes, although occasionally, Southern animals demonstrate this wide banding. The wide lines of the Sefton animals provide superb camouflage in their marram grass habitat.