We asked a trichologist and a bunch of hair experts how often you should wash your hair — and it turns out there's no right answer

In order to figure out a maintenance schedule that works for you, identifying which category your hair falls under — straight, wavy, curly, or extra curly (coily) — is a good place to start. However, according to Hannah Reid, a stylist at Nine Zero One Salon and a certified trichologist technician, there are many factors that determine someone's hair type. These include hair texture, structure, porosity, and density.

Your hair texture refers to your natural curl pattern. It's established by your genetics, but can be altered through chemical processing and environmental factors. Since certain textures of hair respond differently to certain types of shampoos, it's good to identify your hair type first and foremost.

It's easy to determine what your natural hair texture is. All you have to do is shower and let your hair dry without any product in it.

"If it dries without a bend or S shape then your hair is considered straight (type 1)," explains Reid. "If your hair dries with a slight bend or S shape then your hair is considered wavy (type 2). If your hair dries with what looks like a loop pattern or defined curl, your hair is curly (type 3). If you have extra curly or coily texture (type 4) your hair will have spirals or a zig zag pattern."

Straight hair tends to require more frequent washing and lighter-weight formulas, while curlier hair can usually handle denser, more moisturizing shampoos and longer times between washes.

Your hair structure refers to the diameter or thickness of one individual strand and is categorized as either fine, medium, or thick (coarse). In order to determine your hair structure, Reid suggests plucking a single strand of hair from your head and laying it next to a piece of sewing thread.

"If your hair strand appears to be thinner than the thread, you have fine hair," Reid tells INSIDER. "If it appears thicker than the thread it is considered thick (coarse). Anything in between is medium."

Fine hair generally requires more frequent washing than coarse hair.

People often confuse hair structure for hair density, but they are not one and the same. While hair structure is determined by one single strand, your hair density refers to how much hair is on your head, per square inch.

The average person has roughly 2,200 strands of hair per square inch, but to count out that many pieces per square inch would be tedious. Instead, in order to determine your hair's density, Reid suggests putting your hair to the ponytail test.

"Put your hair in a ponytail then measure the circumference of your ponytail," instructs Reid. "If it measures less than 2 inches then it has low density. If it measures 2 to 3 inches then it's medium, 3 to 4 inches it's high density."

Low-density hair generally requires more frequent washings.

Like a sponge, your hair is porous in that it absorbs and retains moisture and oils. The question is, how well does it do this?

If your hair is highly porous, meaning the cuticle layer has gaps and tears in it, it absorbs moisture too quickly and releases moisture at a very high rate, says Reid. "This makes the hair dry, brittle and easily prone to breakage." But if your hair has low porosity, the cuticle layer doesn't open enough and barely absorbs any moisture at all. This can lead to product buildup, "because it is not actually penetrating into the hair shaft."

Generally, low-porosity hair will need to be washed more often due to product buildup, while high-porosity hair can go longer between washes.

Hair with medium porosity — in which case the cuticle doesn't open too much or too little — is the easiest to manage, Reid says. It allows in and retains just the right amount of moisture to make styling and coloring a breeze, and generally looks the healthiest, too.

So, how can you determine your hair's porosity? The easiest way is to fill a bowl of water and place one strand of hair in it, Reid says. "If it sinks to the bottom that means you have high porosity. If it floats below the surface, but doesn't touch the bottom, you have normal porosity. If it floats at the top of the water, you have low porosity."

In terms of a golden rule for how often you should wash your hair, the jury's out. Most people will need to experiment to figure out what works best for them, but some experts, like Garren, celebrity stylist and co-founder of R+Co, tell INSIDER that as long as you have the right products for your hair type, you can technically shampoo daily, should you have the desire (or time).

Kien Hoang, Oribe Director of Training and Content, recommends normal to straight hair types should wash their hair every two days. According to Irinel de León, a celebrity stylist and brand ambassador for Ouidad, curly to coily hair types have a longer timeframe to play with, ranging from once a week to once every two to three weeks.

High-density hair can be washed less frequently than low-density hair, as thinner strands tend to get dirtier, faster, says Nine Zero One stylist Sarah Klein. Coarser hair can also last longer without shampoo.

But the state of your hair – if it's oily, dry, normal, processed, or color-treated — should also be taken into consideration.

Hoang recommends washing color-treated hair every three days or so with products designed specifically to protect the longevity of dyes. "If the hair is oily, it should be washed daily and treated weekly to a clarifying shampoo."

"A good average amount of time to wash your hair is two to three times a week," says Klein, but how often you wash your hair will ultimately vary on the aforementioned factors, plus your lifestyle. "You can train your hair to require less washing. As you minimize the days you shampoo, your hair isn't being stripped down by the shampoo and other products, and it will start to produce less oil."

Because every hair type has different needs, it's important to familiarize yourself with the types of products and ingredients that best nourish your unique strands.

Representatives from the R+Co Developmental Team tell INSIDER that fine hair types should look for product labels with ingredients like botanical extracts, amino acids, biotin, and proteins that provide strengthening benefits.

Reid suggests curly and extra curly hair types, who are prone to dehydrated locks, look for ingredients that seal in moisture, like shea butter, as well as jojoba, coconut, and argan oils that prevent strands from swelling from too much water. Keratin amino acids also help repair, strengthen, smooth, and soften hair, he says.

While your strands require certain ingredients to keep them healthy and strong, there are also specific ingredients that can be damaging for your hair, like sulfates and drying alcohols.

So when shopping for the best shampoos, conditioners, and other shower staples like hair masks, make sure you're reading their ingredient labels thoroughly. While bottles will label themselves "sulfate-free," oftentimes they are referring to the strongest sulfate, sodium lauryl sulfate, says de León. Below is a list of alcohols and sulfates she tells INSIDER all hair types should avoid.

• Ammonia Laureth Sulphate
• Sodium Laureth Sulphate
• Sodium Lauryl Sulphate

• Alcohol denat
• Ethanol
• SD alcohol 40
• Propanol
• Isopropyl
• Propyl

In addition to sulfate and alcohols, you should also be looking out for ingredients that can be damaging to your specific hair type. Below is a list of specific ingredients the R+Co product development team tells INSIDER that fine-textured and curly textured hair types should steer clear of in order to best preserve their strands.

For fine-textured hair, avoid:

• Mineral-derived ingredients like petrolatum
• Animal-derived cationic, waxy materials

For curly- and coily-textured hair, avoid:

• Excessive mineral powders
• Excessive starches
• Talc

It's important to note that your hair and your scalp are two very different things: your scalp is alive and your hair is dead, therefore they need to be treated differently, Reid tells INSIDER.

"When we are going through our day, there are many things such as pollution, environmental factors, products, that all sit and build up on our scalp, which can cause the hair follicle to get clogged and suffocate your hair," says Reid. "It's very important that you cleanse all of that off of your scalp so that your hair follicle can be properly cleaned and be able to breathe."

On that note, Reid insists washing your scalp at least every three days with a product formulated for scalp health, like the Hairstem Shampoo by Advanced Trichology, to remove all of the debris and any DHT build up.