Context. Each year, millions of reptile skins are commercially exported from Southeast Asia for exotic leathers. Quotas are commonly used to regulate this trade, but quotas are sometimes exceeded and do little to ensure harvest sustainability.

Aims. To explore the relationship between the size of live pythons and their skins, and to assess whether skin measurements can be used to enforce the application of limits on the size of harvested snakes.

Methods. We measured the body size of three heavily harvested python species (Malayopython reticulatus, Python breitensteini and Python brongersmai) in Indonesia and Malaysia and examined the relationship with skin length, skin width, the size of the ventral scale and its adjacent dorsal scale.

Key results. Measurements of 2261 pythons showed strong relationships between the size of live pythons and measurements made on their skins. Skins can be stretched 30% longer than the body length of snakes from which they came and inter-facility and country differences in stretching technique result in different relationships between the sizes of live snakes and the measurements made on their skins. Male and female Malayopython reticulatus differed in their skin dimensions relative to the size of the live snake, but these differences were minor.

Conclusions. Despite variations in stretching techniques, in functional terms, this variation is minor (maximum 3.5% relative to each mean measurement) and does not limit application of skin sizes for regulating trade within an acceptable level of error. However, differences in the stretched length of Indonesian and Malaysian skins were much greater (5.9% of the mean length of skins), and, thus, each country should apply its own limits and predictive tools.

Implications. The strong relationship between the skin size and the size of the live snake offers great potential for regulating trade by using skin-size limits. Inspection of the size of skins can be used to enforce harvest-size limits and focus harvesting away from sexes and life stages most critical for population persistence. This management tool has numerous advantages over current regulatory practices (quotas) and should be considered for management of trade in Asian reptile skins.