Most adults have 12 molar teeth: six on the top jaw and six on the bottom. That total includes three molars on each side of each jaw, for a grand total of four sets of three. Molars are the large, flat teeth at the very back of your mouth, and they make up more than a third of your 32 permanent teeth.
The Three Types of Molars
Your 12 molars break down into three distinct groups, named simply by their position from front to back.
- First molars (4 total). These are your earliest permanent molars, often called “six-year molars” because they typically push through the gums between ages 6 and 7. They sit just behind your premolars.
- Second molars (4 total). Sometimes called “twelve-year molars,” these erupt behind the first molars during early adolescence.
- Third molars (4 total). Better known as wisdom teeth, these are the last to arrive, usually between ages 17 and 21. They’re also the ones most likely to cause problems or never show up at all.
Why You Might Have Fewer Than 12
Twelve is the textbook number, but a large percentage of people never develop a full set. Roughly 38% of the population is missing at least one wisdom tooth from birth, a condition called third molar agenesis. The rates vary widely by background: studies have found prevalence as low as about 12% in British populations and as high as 41% in Korean populations. Indian Punjabi populations sit around 11.5%, while Malaysian Malays are closer to 30%.
Even when wisdom teeth do develop, they’re frequently removed. They can come in at odd angles, crowd neighboring teeth, or get trapped beneath the gum line. So in practice, many adults walk around with 8 molars rather than 12, and that’s completely normal.
What Molars Actually Do
Each molar has a broad crown with four or five rounded cusps on top. That wide, bumpy surface is built for one job: grinding food into pieces small enough to swallow. Your front teeth (incisors) cut food, your canines tear it, and your premolars start crushing it down. Molars handle the final stage of chewing, breaking everything into a soft, manageable consistency before you swallow.
This is why losing a molar has a bigger impact on chewing efficiency than losing a front tooth. The surface area of a single molar dwarfs that of an incisor, and the jaw muscles exert the most force at the back of the mouth where molars sit.
Molars vs. Premolars
A common point of confusion is the difference between molars and the teeth right in front of them. Most adults have 8 premolars (also called bicuspids), which sit between the canines and the first molars. Premolars are smaller, usually with only two cusps, and they share features of both canines and molars. They crush and tear food, but they don’t provide the same broad grinding surface that true molars do. If you’re counting the flat teeth in the back of your mouth, the two closest to your canines on each side are premolars, and the two or three behind those are your actual molars.
When Each Molar Appears
Unlike most permanent teeth, first molars don’t replace a baby tooth. They emerge behind the last primary molar in a child’s mouth around age 6 or 7, which is why parents sometimes miss them entirely. Second molars follow a similar pattern, appearing behind the first molars during adolescence. Wisdom teeth are the slowest, often not erupting until the late teens or early twenties, if they erupt at all.
Because first molars arrive so early and sit so far back in a young child’s mouth, they’re especially vulnerable to cavities. Kids may not brush them thoroughly, and parents may not realize they’re there. Keeping an eye on those back corners of your child’s mouth starting around age 6 can save a lot of dental work later.