How should wellies fit? - Should I size up or down

Wellies or rain boots should feel comfortable. If you are wearing this type of footwear, it generally means you will be covering some distance outside in often wet conditions.  

It is usually a good idea to go up a size with a welly. The boots needs to fit in the foot, the ankle and the leg, so getting all three to be perfect can be tricky. If you go up a size, it allows room for thicker winter socks to keep your toes and feet warm in the colder months. In the summer months when you don't need thick socks and you find that you are slipping around in the foot area, you can add in comfortable insoles. There are amazing shock absorbing insoles that make walking long distances a happy experience. There are warm cushioning ones and supportive ones that will make your summer walks in thin socks comfortable and more enjoyable. 

Wellies are more difficult than other shoes to size, as they have no laces, or straps to adjust them so its important that you try them on. 

Wellies are made from rubber which is heated to a very high temperature and then moulded to a last (the foot shape). The rubber then hardens into shape as it cools. That means that you can stretch your boots with applying heat from a hairdryer onto the specific areas but it is important to remember that you need to wear the boots in for a few days before doing anything, as they will naturally mould to your feet. If you have worn the boots for more than a few days and they are still too tight, then you can apply heat to the critical area for some minutes and then you must wear the boots to maintain the new shape that you have created.