Before getting a hair transplant, many people are in the dark about the things that make or break the success of the surgery. You might know that surgeons will take hair grafts from the donor area, but it’s not as simple as that. The number of grafts needed for the transplant also needs to be decided beforehand.
That’s why it’s a good idea to know about what’s known as “grafts per cm2” that you’ll need in your hair transplant. If too few or too many grafts are taken from the donor area, that’ll botch the results. Moreover, if the “correct” number of hair grafts is not put in the balding area, you might not end up satisfied with the results.
The number of grafts per cm2 you’ll need is a general estimation. Of course, the exact number can vary between patients. However, it’s a good way to spot a red flag when you’re deciding between different clinics.
It’s true that the purpose of hair transplant surgery is to mimic the natural hair density so that you end up with natural-looking results. But there’s no cut and dry answer to that. So, without further ado, let’s find out more about it.
What is The Natural Hair Density?
To understand how many hair grafts per cm2 you’ll end up getting in transplant surgery, you need to know about the natural hair density.
Normally, per cm2, we have 50 to 80 hair grafts. And each hair graft, also known as a follicular unit, can have up to 5 hair follicles/strands. Typically, one hair graft contains 2 hair follicles. You can do the math yourself, but you’ll end up with 100-160 strands per cm2. If the person has 5 hair follicles per graft, they’ll have 250-400 hair strands per cm2.
If you’re curious about how many hair strands you have on your entire scalp, well, that depends on the size of your head. Males have larger head sizes than females. So, they need more grafts per cm2.
Factors Affecting Hair Density
Before we get into this, remember this isn’t the case for everyone. However, normally, which factors affect hair density?
Here we’ll spell out that word again – genetics. They determine even the smallest details about your scalp and hair follicles. The hair colour, texture, thickness, density, and, of course, longevity are all down to your genes. When you’re getting a hair transplant, the surgeon will consider these factors. Why?
Let’s take the case of two people. One has thicker hair follicles, and the other has thinner hair follicles. Now, even if the person with thicker hair follicles has fewer grafts per square centimetre, the thickness of the hair strand doesn’t let it show.
However, if the person with thinner strands has fewer grafts, the scalp will start showing through. Thus, harvesting enough grafts for hair transplantation is no easy feat. Curly hair will also look denser than straight hair.
Number of Hairs Per Graft
Again, it comes down to your genetics. However, the surgeon will find out the number of grafts you have and the average number of hair follicles that you have per graft before the surgery. That’s because, let’s say, if someone has 2 hair follicles per graft, they’ll need 2 grafts to have the same number of follicles as someone who has 4 follicles in just one graft.
This impacts the number of grafts that the surgeon will harvest. Someone who has more hair follicles per graft can achieve more hair density with fewer grafts than someone who has fewer hair follicles per graft. Your natural hair density depends on this. If you have 3-5 hair follicles per graft, you’ll have naturally denser hair.
That’s all on you. Over-grooming isn’t something that your hair quite appreciates. If you dye your hair too much or put other harmful chemicals on your hair through shampoos, mousse, sprays, or masks, you’re going to damage the hair follicles. It can cause thinning.
In some cases, the damage is permanent. That will end up decreasing your hair density. You’ll end up with thinner and less dense hair. Moreover, it affects the number of hair follicles you have per graft. So, be kind to your hair!
That’s another thing that can impact hair density. Hair loss due to thyroid conditions, alopecia, skin infection, pregnancy, and autoimmune conditions can all make your hair less dense. You’ll end up with a fewer number of hair follicles per graft, or the overall number of grafts per cm2 will decrease because of permanent damage.
How Many Grafts Per Cm2 Do You Get in Hair Transplant?
There are some factors that determine hair transplant density. Let’s find out about them.
Donor Area Density
Your surgeon simply won’t take a bunch of grafts from the donor area to fully cover your thinning areas. This can cause permanent damage to the donor area due to over-harvesting. It’s irreversible, and you’ll end up with almost a bald patch on the back or sides of your head forever.
The number of hair grafts that the surgeon will take from the donor area depends on the density of the donor area. If the density of the donor area is poor, only a limited number of grafts can be taken.
Area of Baldness
How large the balding region is will affect the overall hair density. If the balding is extensive, it will require more coverage, which will, of course, decrease the hair density. The grafts are more spread out so that the whole area gets coverage.
That’s one of the most important things after your hair transplantation. You need to make sure that you’re looking after your scalp just as the surgeon instructed. Done wrong, you can permanently damage the transplanted grafts, and no hair will grow from them. This will decrease the overall hair density due to a decrease in the number of grafts per cm2.
What Is the Total Number of Grafts Per Cm2 That You’ll Get?
That depends on the region(s) of the scalp in which you are balding. You can calculate the total number of grafts that you’ll need using our graft calculator. Keep in mind that there’s a limit to the maximum number of grafts the surgeon can harvest. It varies from patient to patient.
The point is to not permanently damage the donor area. If the recipient area is not that large, fewer grafts will be taken from the donor area. If it’s large, the surgeon will increase the donor area from where they’ll harvest.
Grafts Per Square Centimetre For Best Results
Normally, you have 50-80 grafts per cm2, but the scalp starts showing through when the density drops to 20-40 grafts per cm2 i.e., typically, you’ll end up with 40 to 80 hair strands in each unit area. So, the surgeon aims to reach the “normal hair density range” in transplantation. However, the number of grafts that you’ll get per square centimetre can vary depending on the hair transplant technique.
FUE Hair Transplant
The surgeon can achieve a hair density of approximately 55-65 grafts per cm2 in the recipient area when performing a traditional FUE surgery.
Direct Hair Implantation (DHI)
The surgeon can achieve a maximum hair density of 70-80 grafts per cm2 in the balding region through a DHI transplant.
The factors mentioned above impact the hair density that you can achieve with transplant surgery. If a patient has thick hair, the surgeon can achieve good density by implanting fewer grafts per square centimetre. If the hair’s thin, the diameter of the grafts will be smaller, so the surgeon needs to implant more grafts per cm2.
What Happens If the Hair Density Is Too High?
The grafts simply won’t survive. Many patients want to achieve high hair density after transplant, but they don’t know that transplanting hair grafts too close together will ruin the results of the surgery.
If a surgeon attempts to do that, they’ll make too many cuts on the skin, which will end up cutting the blood vessels. This will reduce the circulation of blood in the area, and your newly transplanted grafts won’t get oxygen or nutrients to survive. The skin there will start to die, which is known as necrosis. This is irreversible. No hair will grow from there. That is why the experience of the surgeon truly matters in your surgery!
Think before deciding on a clinic. There’s a science to the number of grafts that you need and should get when you’re getting a hair transplant. There’s no one size fits all for this, as there are many factors that impact the final hair density.
Using calculators, you can find out the number of hair grafts that you’ll need for the surgery. However, it’s not necessary that the surgeon will end up harvesting as many.
That’s because if you have thicker hair or more follicles in one graft, you won’t end up needing as many grafts per cm2 for natural coverage. It isn’t the case for those with thinner hair or fewer hair strands per graft.
Reviewed and Approved by Dr. Hassan Soueid.