Prose vs. Function of Beauty: An Honest Comparison of the Two Custom Haircare Lines

I sometimes joke that on a bad hair day (which is most days), I look like Albert Einstein. Hair in all directions, but without the genius credibility that would render me anything other than...crazy. Once I discovered the power of silk pillowcases, things improved drastically, but they didn’t completely solve my problem of having flat, fine hair that can’t go an hour in the heat without getting frizzy. Enter: custom hair care products. I had seen a few different brands floating around and my interest was piqued—could they really do a better job than run-of-the-mill shampoos and conditioners? I decided to test the top two competitors in this space: Prose vs. Function of Beauty to see how they stacked up against each other.

Both Prose and Function of Beauty offer custom hair care regimens, which are formulated based on a questionnaire you fill out. Both brands also have discounts if you purchase their products on a subscription basis. Prose offers a 15 percent discount on their shampoo and conditioner, which is normally $32/bottle (8.5 ounces), making it $27/bottle. Similarly, Function of Beauty has a discount on their 16-ounce bottles of shampoo and conditioner ($27), which go for $22 when you subscribe.

Prose ships its products monthly, while Function of Beauty ships every other month, depending on the size of the bottle you choose. On that note, Prose has one 8.5 ounce-sized bottle for its shampoo and conditioner, whereas Function of Beauty’s come in either 8- or 16-ounce bottles.

The brands build your custom formula based on the results of their questionnaires. I found that Prose’s questions were more comprehensive, gathering a host of information across hair, lifestyle, age and geographic categories, while Function of Beauty focused more on hair alone (i.e., whether you color your hair, your styling preferences and goals).

Prose and Function of Beauty both offer the same core products: custom shampoo, conditioner and hair masks. Where the lines diverge is Function of Beauty has more products tailored to color-treated hair and styling products, while Prose has more products that cater to curly hair, as well as a supplement line.

Prose

• Custom shampoo: $32 (8.5 ounces)
• Custom conditioner: $32 (8.5 ounces)
• Custom pre-shampoo scalp mask: $45 (8.5 ounces)
• Custom pre-shampoo hair mask: $45 (8.5 ounces)
• Custom styling gel: $30 (8.5 ounces)
• Custom Root Source: $62 (one month supply)
• Custom hair oil: $48 (1.7 ounces)
• Custom dry shampoo: $28 (1.4 ounces)
• Custom leave-in conditioner: $28 (5.1 ounces)
• Custom curl cream: $28 (5.1 ounces)

Function of Beauty

• Custom shampoo: $21 (8 ounces) / $27 (16 ounces)
• Custom conditioner: $21 (8 ounces) / (16 ounces)
• Custom hair mask: $24 (7.5 ounces)
• Custom leave-in conditioner: $24 (8 ounces)
• Custom hair serum: $29 (3 ounces)
• Custom styling primer: $29 (6 ounces)
• Custom co-wash: $30 (16 ounces)
• Custom purple shampoo: $21 (8 ounces)
• Custom purple conditioner: $21 (8 ounces)
• Purple mask: $24 (7.5 ounces)

Both brands formulate their products without sulfates and parabens. (Though it’s worth noting that neither are inherently bad for you, as we recently learned from cosmetic chemist Dr. Michelle Wong of Lab Muffin Beauty Science.) And while the brands do use silicones in some of their products (namely their conditioners), silicone-free options are offered as well.

On their site, Function of Beauty explicitly states that they conform to the EU’s cosmetic guidelines, which ban about 1,400 ingredients (vs. The FDA’s 11, per The Guardian). The colors used in their products are approved by both the FDA and EU, but customers can choose to go dye-free. As for fragrances, Function of Beauty uses natural fragrances derived from essential oils, but you can also opt for fragrance-free products.

Meanwhile, Prose has its own “Never List,” which is a list of 29 ingredients they avoid in their formulas. This includes petrolatum, parabens, formaldehyde, talc and chloride, to name a few.

For context, my hair is straight and fine. It’s not color-treated, and I typically wash it every day. On occasion, I will blow dry or style it with the Dyson Airwrap.

I am susceptible to split ends, dryness and frizz, especially after I’ve heat-styled my strands and I’m notorious for never using thermal protection, despite knowing better. I suspect some of my hair woes can be attributed to the fact that I live in New York City, which, according to Prose, means my hair is heavily weathering the wind, UV rays, pollution and humidity.

To test these two brands, I tried a custom shampoo and conditioner from each over the course of eight weeks. When creating my formulas, my priorities (according to their questionnaires) were volume, shine and softness.

• Pros: comprehensive questionnaire, B-Corp, Climate Neutral certified company, beautiful packaging, good scent options, curly hair care  
• Cons: product bottles are small
• Value: 17/20
• Efficacy: 19/20
• Scent: 19/20
• Customization options: 20/20
• Ingredients: 18/20
• Total: 93/100

For my custom Prose formula, I wanted something that would give my hair more volume, shine and smoothness, as it often feels coarse after heat styling. The shampoo and conditioner I received came in the “Prelude” scent, a fresh blend of rose, geranium and blue iris that wasn’t too overpowering. Some key ingredients included fermented rice water, yucca stem extract, red algae extract and jasmine flower water to cleanse and moisturize my scalp and strands.

Typically when I use a blow dryer, my hair often looks a little frizzy and feels coarse afterwards, but while I was using the Prose shampoo and conditioner, I found that my hair stayed soft and silky—even after drying and curling it.

I also put the products through the sweat test. (New York summers are incredibly humid.) After a day of trudging through subway tunnels swampier than a Louisiana bayou in July or Lindy Hopping my way across Central Park, my hair usually looks terrible. But I’m happy to report that despite sweating buckets, my hair held up pretty well.

• Pros: follows EU regulations on safe ingredients, great value, dedicated products for color-treated hair, post-consumer recycled packaging
• Cons: does not offer dry shampoo
• Value: 19/20
• Efficacy: 18/20
• Scent: 19/20
• Customization options: 16/20
• Ingredients: 20/20
• Total: 92/100

The first thing I noticed when I received my Function of Beauty package was that the bottles were ginormous. When subscribing, you can choose between 8- and 16-ounces, and I had been sent the latter. Similar to the hair goals I selected with Prose, I chose to focus on volume, shine, anti-frizz and root health.

The shampoo and conditioner came in the “Floret” scent, a combination of rose and gardenia with sandalwood. I found it to be feminine and floral but not so overpowering that I couldn’t perfume my hair, which I often do. If you prefer a stronger scent, you can indicate this in the questionnaire (light, medium or strong). The key ingredients in these formulas included coconut extract, tamarind extract, acacia extract and baobab seed extract to smooth and protect my hair against UV damage.

Per the instructions, I double-washed the first few times, and the results were incredibly silky and bouncy. My hair also stayed clean, despite the fact that I spent three hours dancing outside on a hot and humid June afternoon, and then briefly napped on the Great Lawn in Central Park. Usually, it doesn’t take much for my hair to start looking dirty, so I was impressed. (It may have even done a marginally better job than Prose in this department.)

As for heat styling, I think my hair stayed fairly soft and shiny, though here is where Prose may have come out on top.

Overall, I would say Function of Beauty is more cost effective, at about $1.70/ounce compared to Prose at $4/ounce. Though Prose seems to have a more comprehensive scope of what each client’s hair needs via its extensive questionnaire. Another point of differentiation to consider is that Function of Beauty offers products specifically tailored to color-treated hair, while Prose has products that cater to curly hair. As someone with straight, non-processed hair, I found that both worked equally well for me.

So which one would I crown the winner? It’s hard to say because I appreciate the relative affordability of Function of Beauty, but as a sustainability advocate, I like that Prose is B-Corp and Climate Neutral certified, so Prose might take the lead for me here…but only by a hair.

Want to know which buzzy products are *really* worth buying? Sign up for our shopping newsletter to uncover our favorite finds.