Heat Index: How Hot is Too Hot?



Hot tools are essential stylers in your hair routine, but they can also cause breakage, split ends, and a crispy texture. Although a topical heat-protector can help, it's also important to turn down that dial! But how do you know if you are styling or scorching your strands? We chatted with Hollywood hair stylist Philip B. (Halle Berry and Charlize Theron are fans of his luxe hair care line) to discover the safest degrees for flat irons, curling irons, and blow-dryers—so you can style safely!


When using a flat iron, never go above 400 degrees Fahrenheit! "Stay within the 300's—even 395 degrees is fine for most hot styling tools. As soon as you go above the 400-degree level you're really playing Russian roulette," says Philip. "Think about it: Hair, like paper, begins to melt at about 451 degrees. There's no reason to get near that number, no matter what style you're trying to create." Crank up the dial past 400 and you’ll spot split-ends almost immediately.

So how do you know where you fall in the range? "Your hair's maximum temperature tolerance depends on its condition,” explains Philip. “If it's fine, dry, fragile or damaged, stick with a lower temperature in the 290 to 300 degree range.” But even if you have thick, coarse hair, go with 300 to 340. Either way, one rule applies: Condition, condition, condition. Your hair will be best protected from any type of heat styling if it has a healthy balance of moisture and protein."


When it comes to applying a curling iron to your tresses, Philip suggests you stay in the 300 to 340 degree zone. "If you're just running the curling iron through your hair quickly to give it some wave and tame trouble ends, you can go with a higher heat limit: 350 to 360 degrees." he suggests. "If you're creating a more structured, retro look and need to hold your hair in the iron for more than a few seconds, go with a lower temp, 275 to 300 degrees."


Unlike irons, most blow-dryers don't come with a degree-setting dial. If your dryer does, Philip suggests staying in the 80-100 degree range. For the rest of you Beauties, keep the blow-dryer on the medium-high setting. "The key with blow-dryers is to get one that combines heat with a powerful fan speed, so you can dry your hair quickly. Dryers with high heat and low fan speeds end up baking your hair and lead to breakage and split ends," says Philip. The more intensely focused the heat, the lower you should go with it. Another easy way to avoid burning your mane? Always blow-dry in sections. "You might also want to consider blowing your hair halfway dry, and then letting it air-dry from there," advises Philip. "That puts less stress on the hair than taking it from 100% wet to 100% dry."