A fragrance concentration refers to the strength that a fragrance has. Perfumes with a higher fragrance concentration contain more fragrance concentrate and less alcohol. Fragrance concentrations are broken into categories including parfum, eau de parum, eau de toilette, eau de cologne, and eau fraiche.
Parfum, also known as extrait de parfum or pure perfume, has the highest fragrance concentration. Parfum will contain anywhere from 15% to 40% fragrance however concentration is generally between 20% to 30% for most parfums. Of all scents, parfums last the longest; usually six to eight hours. Parfum generally also commands the highest price of all the fragrance types due to the high concentration of fragrance. People with sensitive skin may do better with parfums as they have far less alcohol than other fragrance types and therefore are not as likely to dry out the skin.
Eau de Parfum
After parfum, eau de parfum (EDP) has the next highest concentration of fragrance. Eau de parfum generally has a fragrance concentration of between 15% and 20%. On average, eau de parfum will last for four to five hours. It is also generally less expensive that parfum and while it does have a higher concentration of alcohol than parfum, it is better for sensitive skin than other fragrance types. Eau de parfum is one of the most common fragrance types and is suitable for everyday wear.
Eau de Toilette
Eau de toilette (EDT) has a fragrance concentration of between 5% and 15%. It is cheaper than eau de parfum and is one of the most popular types of fragrance available. EDT fragrance will normally last for two to three hours. Eau de toilette is considered by some to be for daywear while eau de parfum is considered nightwear. The term eau de toilette came from the French term "faire sa toilette" which means getting ready.
Eau de Cologne
Eau de cologne, or EDC, has a much lower concentration of fragrance than the above types of perfume. EDC generally has a 2% to 4% percent concentration of fragrance and a high concentration of alcohol. It is cheaper than other types of fragrance however the scent generally only lasts for up to two hours. EDC generally comes in bigger bottles and more of the fragrance needs to be used. Originally eau de cologne referred to a traditional recipe that used herb and citrus notes with little anchoring with base notes.
Eau fraiche is similar to eau de cologne in that the scent will generally last for up to two hours. Eau fraiche has an even lower concentration of fragrance than eau de cologne, normally only 1% to 3%. While eau fraiche has a low fragrance concentration, it does not contain a high amount of alcohol. Along with the fragrance, the remainder of eau fraiche is mostly water.
Source: A Guide to Perfume Types