Yes, hair grows per hour, albeit very slowly.
How Fast Does Hair Grow?
The average hair growth rate is approximately 0.3 to 0.4 millimeters per day. To determine the hourly growth rate, we can perform a simple calculation:
- There are 24 hours in a day.
- Dividing the daily growth rate by 24 gives us an approximate hourly growth rate of 0.0125 to 0.0167 millimeters per hour.
This means hair grows only a tiny fraction of a millimeter each hour. While imperceptible to the naked eye, this consistent growth adds up over time, resulting in noticeable hair growth over weeks and months. Different factors like genetics, hormones, and nutrition influence this rate.
Several sources corroborate this information:
- Live Science: States that hair grows at an average rate of 0.01 inch (0.35 millimeters) per day. https://www.livescience.com/42868-how-fast-does-hair-grow.html
- Reddit (r/HaircareScience): While this source discusses experiments on hair growth, it doesn't provide a precise hourly rate. https://www.reddit.com/r/HaircareScience/comments/18lziob/how_fast_does_your_hair_grow_appoximately/
- Reddit (r/theydidthemath): Calculates hair growth at an extremely small rate in miles per hour, confirming the slow growth. https://www.reddit.com/r/theydidthemath/comments/c3dhml/request_in_miles_per_hour_how_fast_does_human/
The perception that hair grows back quickly after shaving is due to the hair already being present under the skin. Shaving only removes the visible portion, not the hair root.
