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Shampoo serving size: two teaspoons

How much shampoo you needs depends on a bunch of factors, including how much hair you have, its texture, and how often you shampoo. But most women need about two full teaspoons, according to the experts at Head & Shoulders . You’ll know you’ve used enough if the liquid works into a rich lather and provides coverage all over, so you get the max cleaning action. If your hair is long, thick, or curly, you may need more shampoo to avoid leaving behind dirt, oil, and product build-up. Here’s how to find the best kinds of shampoo for your hair type.