The number of diaper covers you will need entirely depends on which covers you buy and how often you plan on washing them. We recommend starting your service with the Ten Week Diaper Trial Program which includes 8 assorted diaper covers. You will quickly discover your favourites.
PUL covers are trim and waterproof. They fit small babies very nicely. They are economical and come in really cute prints. Some people find they retain smell more than fleece or wool and they leak around the legs a bit more often.
Fleece covers trap in moisture by wicking it back into the diaper and making it work better. They don't retain smell as quickly as PUL covers, dry very quickly and allow for breathability. They can be used more times between washes too. Bulk can be an issue for some people, but our fleece covers are quite trim through the thighs.
We have two types of wool covers and they both work increadibly well. They repel moisture like the fleece covers and wick it back into the diaper. Wool needs to be lanolized but will not need to be washed have as often as fleece covers, as it is naturally antibacterial.