It is very important that a sleeping bag is neither too big nor too small. Both scenarios will compromise the heat retention. Always make sure you are somewhat below the “body length” count that is stated under “Measurements” for each sleeping bag on out website. Medium: Up to 175 cm. Large: Up to 190 cm X-large: Up to 205 cm. Additionally, be aware of other measurements such as width at the shoulders and hips. If you wish to store clothes in your bag, maybe size up to make sure there is space.