How to Calculate Growth Retention

Hair Growth Chart It is commonly known that the average person grows .50 inches of hair per month. These calculations will help you understand how much of the .50 inch you are actually retaining on average of a 90 day period.

  1. Use your natural hair growth shirt to mark your current stretched length as day 0.
  2. 30 days later, mark your growth shirt again with your stretched length.
  3. 60 days later, mark your shirt again with your stretched length.
  4. 90 days mark the shirt once more with your stretched length.
Common length milestones are great gauges along your growth journey. The most common milestones are:
  • top center of your head to ear
  • from ear to chin
  • from chin to shoulder
  • from shoulder to armpit
  • from armpit to bra strap
  • from bra strap to the middle back
  • from the middle back to waist
  • from waist to hips
  • from hips to tailbone
  • from tailbone to classic – half body
  • from classic to thigh
  • from thigh to knees
  • from knees to calf
  • from calf to ankle
  • from ankle to floor

When you are growing your hair it can be divided into 3 parts: (1) no growth shirt needed, (2) growth shirt useful and (3) outgrew growth shirt. Using the common length milestones as gauges offer a great advantage - they are constant. To gauge your growth using your body parts is a stellar idea!

To begin, you will need to determine baseline measurements for the right side of your head, left side of your head, the front center, the back center (nape of neck) and the middle crown area. Measuring the distance between each aforementioned baseline measurement at the 30, 60 and 90 day interval and take the average.

For example, look at the right side measurement:

  • Beginning measurement = 8.75
  • From day 0 to day 30 (1st 30 days) = 8.75
  • From day 30 to day 60 (2nd 30 days) = 11.00
  • From day 60 to day 90 (3rd 30 days) = 11.00

In this example, the beginning measurement was 8.75 inches on Day 0.

  • From day 0 to day 30, there wasn’t any length retained (0 inches).
  • From day 30 to day 60, I was able to retain 2.25 inches of length.
  • From day 60 to day 90, there wasn’t any length retained (0 inches).

Adding together the inches retained, the total is 0 + 2.25 + 0 = 2.25.

Taking the average total is 2.25 / 3 months = .75 inches retained during month 1 thru month 3.

The Hair Goal

Armed with an average growth retained rate of .75 inches for three months, the goal is to reach middle back length from armpit length. There are seven inches between armpit and middle back length. How long will it take to grow to middle back length if the average growth rate for three months is .75?  It will take approximately 28 months to retain 7 inches of hair.

.75 (average growth rate per 3 months) / 3 months = .25 of inch average/mo.

.25 of an inch/mo. * 4 months = 1 inch every 4 months

Since it will take 4 months to grow 1 inch, it will take 28 months to grow 7 inches.

4 months (to grow 1 inch)  * 7 desired inches = 28 months

The Finding

If the average growth rate is .50 an inch per month and over the past three months only .75 inches were retained – this is a red flag. The most obvious place to start looking is at the regimen and technique. In this example, the first indicator was from Day 30 to Day 90 where there was not any measurable length retention.

This is the point where you would go back and review your natural hair journal to see what you were doing to your hair during that period.

Were you detangling roughly? Were there visible signs of hair breakage in your comb or pieces of hair on the floor?

Were you stressed? Keep in mind that you would need review the last several months of your journal.

Alternatively, you would need to evaluate anything that could prevent you from retaining length.

There are several things that can affect how much length you retain. Below are a few examples:

  • combing your hair when it’s dry
  • combing your hair excessively
  • detangling too roughly
  • trims obviously affect length retention and should be taken into consideration when analyzing your results
  • using heat

Continuing with the previous example, the conclusion is that combing the hair when it’s dry, detangling too roughly and not detangling in small sections are the culprits. To remedy this, try using a detangling product or adding oil to water or conditioner.

It’s also important to remember to dedicate time to detangle and not rip through your strands. Often times, detangling in small sections is beneficial.

Growth Rate Calculation

I really wanted to address calculating your personal growth rate as well; however, there are not many ways that are kind to the hair strands when you consider our attempts to preserve them.

If you have color in your hair, the point where your natural color begins to emerge gives a clear line of demarcation.

However, if you do not wear color there are two additional ways (that I could think of) to calculate your personal growth rate. You can use black rubber bands or braids (no extensions to avoid slippage) in inconspicuous places where you will measure your personal growth rate.

At the end of a 30 day period, measure, clean and condition your hair. Then, replace the bands or braids for the next 30 days and so on.

Your growth rate can be used in comparison to the amount of length that was retained on the ends. You will know the amount that emerged from your scalp based on the measure from the new position of the colored line of demarcation, the rubber bands or braids.

For example, if your hair grew (from your scalp) .75 of an inch, determine if your hair is .75 of an inch longer. If it is, the amount retained (on the ends) will be longer by the amount that grew from your scalp.

On the other hand, if your hair grew .75 of an inch and you did not retain the length on your ends, when stretched your length will be shorter than the .75 of an inch that you grew.

For instance, if your starting length was 10 inches and your average growth rate is .75 for a three month period.

If you retained only .25, then when you stretch your hair to check the length, your hair would measure at 10.25 inches.

If you find this article helpful, insightful or interesting, please leave a comment under the article.

About Jael Byrd

Jael Byrd, who is the founder of Natural Hair Box, has a B.S. in Accounting and works full-time as an auditor. She enjoys bowling, public speaking, reading and writing poetry. To learn more about Jael, read her natural hair story and follow her on Twitter @naturaljael.

Comments

  1. Ok you just dashed my hopes of having bra strap length hair by end of year :-( I think I need to move it to next year now. I’m at a little past arm pit length reaching from the back to front but my crown is still struggling. I do all that I’m supposed to: No heat, gentle detangling, no harsh chemicals, deep conditioning regularly, moisturizing etc etc and STILL I get some breakage. I’m not sure if it’s going to affect my length until I do my next length check in a few days.

    • Hi Michelle, remember this is a example. You will have to use the tools presented to make a customized determination based on the inches you are able to retain. Use the tools presented before making the decision to push the date back, you may surprise yourself. What is the measurement between your armpit and bra strap? Remember, shedding is normal. I would love if you’d share your length checks every month and at the end of the 90 days, share your length retained :) Stay encouraged…

  2. Georgiapeach says:

    This was a very helpful article. Thanks so much for all the tips. I keep a journal because I use a variety if products and constantly change my hair styles. I think of the time I spend logging products as an investment in my hair’s future. Any thoughts on supplements?

    • Hi @Georgiapeach,
      I am happy that you found the article helpful and I hope you will share your progress. The tips- don’t mention it :) You are using your journal in a great way, I agree- definitely an investment. I think supplements have their place but if at all possible, include the needed foods into your every day diet to provide more of a balance. Check out these articles: http://bit.ly/vGUhUo

  3. I took 1 pic using the T-shirt with the lines on it. I have to take another this weekend and I don’t mind sharing.

    My hair would have to grow like a wilderbeast in order to reach bra strap by end of 2011. That’s because the crown is only about 10 inches compared the the rest which is 14/14 1/2 inches. The back sides are at arm pit and that’s still about 3 inches from bra strap.

    it’s ok though. I’ve learned from some mistakes so now my hair is recovering nicely. I just have to wait on the length. It’s long int he back so I usually put the front up so that the 2 lengths are not easily seen.

    • Yea, the all over growth is like a catch 22 b/c each follicle has a different growth rate. I’ve spoken to women and their growth issues were the sides or the back. Depending where your slowest growth rate is I think it dictates a lot of the hair styles we choose. I know for me it’s that way.

      I look forward to your updates :)

  4. So I was super lazy and didn’t take the photo this weekend. I was running alot and didn’t get a chance. Then I”m wondering if I should bother. It’s only been a month. Maybe I should only do length checks every 2 months. There won’t be significant growth in a month and one could only get discouraged if expecting more. What do you think?

    • Hi Michelle,
      Are you doing length checks to calculate your average or are you doing length checks to measure growth ? If you are not calculating your average growth rate over a 90 day period, I can understand not checking every month. So that you don’t become discouraged, try spacing the length checks out until ever 3 months if it is more suitable for you. Also, don’t expect anything, have an open mind about your progress.

  5. I really enjoyed this article…length checking starting this weekend! Great read!

  6. Day 30 finally arrived. Visit my album to see my results! http://naturalhaircommunity.com/members/jael/album/picture/625/

  7. Great post! I know im late but I enjoyed the info and will be sharing the link to this post with my blog readers

  8. I will certainly give this a try and post results.Thanks

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