If you want to buy fabric specifically for your hat, you will need 35 cm main fabric and 35 cm lining. You might need more if you want to pattern match or if your fabric has a strong directional print. To cut out, spread your fabric out right side up. I will demonstrate below with the lining.
The best fabric for making a bucket hat probably would be polyester. That is because of all the benefits that polyester brings to that hat style. With its durability, your polyester bucket hat should last you a long time and through many fishing and hiking trips.
Bucket hats are a trendy accessory that can complete just about any outfit. They are also pretty handy at protecting your hair from the sun. Instead of running off to the store and buying one, why not make you own? They are fast and easy to make.