Loft is a measure of the fluffiness of down. Higher loft means down is fluffier, higher quality and warmer per ounce.
A duvet with higher loft down is NOT warmer than a duvet with lower loft down. We adjust the weights of our duvets to account for differences in loft. The warmth of a duvet is rated using the following categories (from least warm to most warm): Summer, Regular, All Season, Winter.
Check out the infographic here to learn more.