What is the Best Temperature For Straightening Hair?

At what temperature should you straighten your hair for best results and less damage? Discover what the best and safest temperature is to straighten your hair.

How often do you turn the heat up when straightening your hair because you are in a hurry? Raise your hand if you’ve done this at least once, or if you are consistently doing it just because it’s faster and more convenient.

Yes, we get it - you want to finish with your thermal heat styling as quickly as possible so you can move on with the rest of your routine.

Unfortunately, exposing your hair to unnecessarily high temperatures is the main culprit behind heat-damaged hair, especially if you use your styling tools frequently. But what is the best temperature for straightening hair without damage?

This is exactly what we are going to discuss in this article.

Note: if your flat iron doesn’t even have temperature control settings, it might be time to throw it in the bin and invest in a high-quality tool that won’t cause irreversible damage to your beautiful hair. Prevention is better than cure! Learn how to choose a great flat iron in a few simple steps.

Now, back to the main question - what is the best temperature for straightening hair? It depends on a couple of factors:

1. The type of your hair

Undoubtedly, the main factor that determines the best temperature for straightening hair will be the type of hair. Is it wavy, coarse, fine, or very thick and stubborn?

1.1. Hair with fine texture (or chemically treated)

• Fahrenheit: 200°F - 300°F
• Celsius: 90°C - 150°C

The thickness and the shape of hair depend on the cortex, which is the middle layer of the hair and is also responsible for its strength, elasticity, as well as its individual color.

In fine hair, this middle layer is thin and smaller than normal, making the hair strands less compact and weaker. As a result, they are more fragile and prone to breakage, especially when very high heat is applied.

Hair can be either genetically thin or can become thin as a result of specific health treatments, aging, shifting hormones, and other determining factors.

Having said this, the best temperature for straightening fine or chemically treated hair is between 200°F and 300°F (90°C - 150°C).

Fine hair doesn’t require as much heat as thicker hair, so it’s usually recommended to start with the lowest temperature that your flat iron allows.

In addition, high-quality flat irons such as the NuMe Megastar Flat Iron use innovative tourmaline technology that emits negative ions for locking in moisture and creating a frizz free hairstyle even for the thinnest hair.

1.2. Synthetic hair (wigs or extensions)

• Fahrenheit: 200°F - 250°F
• Celsius: 90°C - 120°C

Not all wigs and extensions can be styled, and you should be especially careful with high temperatures.

Fibers that are made from plastic can’t be straightened with a flat iron as they will melt or burn, ruining the wig and causing irreversible damage to the hair fibers. If the wig is made from heat-resistant fibers, use the lowest temperature possible on your flat iron.

If the wig is made from actual human hair, you can heat style it at the same temperatures as regular hair - of course, keeping it in mind that you should start at low temperatures and work your way up if needed for better results.

1.3. Wavy hair

• Fahrenheit: 300°F - 375°F
• Celsius: 150°C - 190°C

Wavy hair has a texture and it sheen between curly and straight hair. It has different patterns, typically ranging from uppercase “S” to a lowercase“s”. This type of hair typically has less root volume as opposed to curlier hair, and the hair strands can range from thin to thick as well.

The best temperature for straightening wavy hair varies between 300°F and 375°F, but the exact temperature will also depend on whether it’s on the thinner or the thicker side.

If you have a thick, coarse hair type, you can go with the higher end of the range (between 350°F and 375°F), but if your wavy hair is thin, try with the lowest temperature on the range first.

If needed, you can always build your way up to something that brings better results.

1.4. Curly hair

• Fahrenheit: 350°F - 450°F
• Celsius: 180°C - 230°C

What gives the hair its beautiful curly shape are the oval-shaped follicles with a twist at the bottom of the hair. When hair moves through round follicles, it gets evenly coated with keratin (a protein that gives the human hair its structure).

Just like most types of hair, curly hair can be thin, medium-textured (normal) or thick and coarse. So, the best temperature for straightening hair will vary depending on each type.

Thick and coarse curly hair usually requires more heat to smooth out the pattern of the curls as opposed to wavy or thin curly hair.

So, if your hair is very dense or thick, you can start with the highest temperature - 450°F (230°C), and then bring it down to 375°F (190°C) once you get your hair styled and you need to polish the final results.

However, if your curly hair is in the thin or medium-textured range, it’s better to start with the lower temperature ranges - 350°F (180°C) and work your way up if needed. This way, you will avoid unnecessary damage while still getting the maximum results.

2. The damage of your hair

Another factor that should be taken into account when determining the best temperature for straightening hair is how much damage it already has.

If your hair is damaged, the rule of thumb is to try and keep your flat iron temperature as low as possible in order to avoid further breakage.

While there are different types of damage, these are the most common ones:

• Mechanical damage - it occurs when you handle your hair too harshly or aggressively (for example, when combing it), or if you wear a tight ponytail way too often.
• Chemical damage - hair coloring and bleaching can be extremely damaging for the hair, especially if it’s done frequently. The hair ends up looking dull and dry.
• Heat damage - when heat damages hair, the shape of the keratin proteins found in the cortex are permanently altered, leading to a structural change and weaker har.
• Sun damage - while damage caused by exposure to the sun can’t be fully avoided (you can’t stay at home 24/7), it also happens - causing the hair to look dry and discolored.
• Stress-induced damage - mental or physical stress can also have a significant impact on your hair. It can make it dry and brittle, which leads to breakage.

While the treatment for hair damage will vary depending on its main causes, it is important to keep in mind that high temperatures may lead to further damage.

So, try to keep the degrees of your flat iron as low as possible, and make sure to invest in a high-quality flat iron designed to straighten your hair gently, such as the NuMe Megastar Flat Iron.

The award-winning Megastar uses proprietary far infrared heat technology to lock in moisture and achieve effortless styling minus the damage.

3. Your thermal heat protectant

And last but not least, the best temperature for straightening hair will also depend on your thermal heat protectant, which is a must before any type of heat styling.

If your heat protectant says that it shields against temperatures of up to 350°F (180°C), avoid going higher than that with your flat iron. Stick to the maximum recommended temperature if there are any limitations. Otherwise, the protectant may not be able to actually protect your hair from damage.

For example, NuMe’s Watch me Werk thermal heat protectant shields your hair up to the maximum temperature possible on your flat iron.

Pro tip: invest in a high-quality flat iron that not only has adjustable heat settings, but also distributes heat evenly. Flat irons made from low-quality materials are unable to distribute heat evenly, which means that you will have to pass the tool through a hair strand multiple times before achieving the final result. However, this causes further damage if you are straightening your hair frequently.

FAQ

What temperature should I straighten my hair at?

The best temperature for straightening hair will depend on your hair type, the damage that your hair already has, as well as the thermal heat protectant that you are using. If you have thin or fine hair, stick to lower temperatures - 250°F - 300°F (120°C - 150°C), and for thick coarse hair, you can increase the temperature to 350°F - 450°F (180°C - 230°C).

What is the highest heat for hair?

The highest heat that you will find on most flat irons is 450°F, or 230°C. However, avoid straightening your hair at the highest heat possible regardless of your hair type, and especially if you have thin or damaged hair, as this will cause further damage.

Is it OK to straighten dirty hair?

Straightening dirty hair is not OK as it may cause additional damage to your hair, since you will be essentially burning oil and dirt. Make sure that it is freshly shampooed, conditioned, and most importantly - fully dry, before you start your heat styling routine.