How Much Hair Product to Use: Measure Your Own Amount

Start with the maker’s amount, if it gives one

Most makers don’t give a measured amount, so it has to come from you. OLAPLEX Nº.4 is the exception: OLAPLEX gives 2.5 mL as an average amount. Use it as a starting point; 2.5 mL may not cover all of your hair.

Some makers’ figures don’t agree. OLAPLEX gives two amounts for Nº.4C: 2.5 mL in its directions and 5 mL in its FAQ. For Nº.5, OLAPLEX’s count of uses doesn’t add up with the bottle size. For both, measure your own amount before working out the cost.

Measure how much you use, once

Use a small scale when the bottle size is given as a weight, or a measuring spoon, syringe or marked cup when it’s given as a volume. You can also weigh the bottle before and after the wash to see how much you used. Keep weight ounces (net wt oz) and fluid ounces (fl oz) apart; they aren’t the same thing.

Counting pumps only helps once you know how much your pump gives. Pump several times into a measuring cup, divide by the number of pumps, and note the result for that bottle. A pump on another bottle may give a different amount.

• Note the product and bottle size.
• Note how many sections you made, and how big they were.
• Measure the total you use, including a second lather or coat.
• Note whether it covered everything and whether extra was left on your hands or in the section.

Adjust for each step

For shampoo, wet your hair more and spread it better over your scalp before assuming you need much more. Some directions say to add water, rub it between your hands first, or lather twice. Count both lathers when you measure. For conditioner or a mask, section size and where you apply it can matter more than a generic coin-size guide.

For leave-in and styler, start with an amount you can repeat and add more only where coverage or hold falls short. If you change both leave-in and gel amounts in one wash, you won’t know which change made the difference.

Let coverage and results guide you

Too little shows up as patches you meant to cover but missed. Too much can leave obvious excess, make rinsing take forever, or change the finish more than you wanted. Those are signs about your amounts, not porosity symptoms. On your next similar wash, use a little more or less of one product, and measure it.

Different parts of your hair may need different amounts. Measure the total, but note whether more went on the scalp, lengths, ends or top layer. Then your next change can be much more precise than doubling the amount all over.

Turn your amount into a cost per wash

Use the same unit for the bottle size and your amount. Number of uses = bottle size ÷ amount per wash. Cost per wash = price ÷ number of uses. If the bottle is labeled in fluid ounces (fl oz), you can convert to milliliters at 29.5735 mL per fl oz. Don’t convert weight ounces (net wt oz) to milliliters.

Monthly cost = cost per wash × washes per week × 52 ÷ 12. It’s still an estimate, because your amount and how often you wash can change. Save your numbers so you compare products the same way.

When the maker gives no amount

Don’t compare bottle prices as if you use the same amount of every product. Enter the amount you measured for each one, or leave the cost blank. The compare page shows each product’s sizes, directions and ingredients side by side. A blank is more honest, and more useful, than an amount made up for the page.

Questions before your next wash