The Data — Skincare
Retinoids: What the Percentage Means
A 1% retinol and a 0.1% retinaldehyde are not one order of magnitude apart. Every form converts down a chain to the same active molecule, and the number on the bottle is a step on that chain rather than a strength.
This guide is research-led: we have not handled these units ourselves. If you buy through our links we may earn a commission — it never changes a pick. How we choose
Skin cells respond to 1 molecule: retinoic acid. Everything sold as a retinoid is either that molecule or a precursor that has to be converted into it, and each conversion step costs potency.
The quick list
Every pick, in order. Jump to the full test on any of them.
- Most-reviewed
CeraVe Resurfacing Retinol Serum
56,888 ratings at 4.6, the deepest evidence base in the category, on a formula that states no percentage at all.
4.6from 56,888 verified reviews - The highest number here
The Ordinary Retinol 1% in Squalane
1% is the largest figure on this page and it is retinol, which sits two conversion steps away from the active molecule.
4.6from 19,823 verified reviews - Where to start
The Ordinary Retinol 0.2% in Squalane
The same formula at a fifth the concentration, which is the honest starting point and the reason the range exists in tiers.
4.6from 5,038 verified reviews Retinal 0.2% Emulsion
0.2% retinaldehyde, one step closer to the active form than retinol — which is why the number is smaller and the potency is not.
4.6from 3,482 verified reviewsNeutrogena Rapid Wrinkle Repair Retinol Serum
52,612 ratings at 4.4, the widest-distributed retinol here, sold on a timeline claim rather than a concentration.
4.4from 52,612 verified reviews
The chain, and what each step costs
Retinyl esters convert to retinol. Retinol converts to retinaldehyde. Retinaldehyde converts to retinoic acid, which is the form the receptor actually binds.
Each of those steps is enzymatic and lossy. The commonly cited working figure is roughly an order of magnitude per step, which is why the percentages on different forms are not comparable to each other at all.
| Form | Steps to active | Availability |
|---|---|---|
| Retinyl palmitate | 3 | Over the counter, weakest |
| Retinol | 2 | Over the counter, the default |
| Retinaldehyde | 1 | Over the counter, stronger |
| Adapalene | 0, a synthetic retinoid | Over the counter in the US |
| Tretinoin | 0, retinoic acid itself | Prescription |
Read the form first and the percentage second. A 0.2% retinaldehyde and a 1% retinol are much closer in effect than the 5-fold gap in their numbers implies.
Retinal 0.2% Emulsion
0.2% retinaldehyde, one step closer to the active form than retinol — which is why the number is smaller and the potency is not.
Current price shown on Amazon. We may earn a commission.
| Form | Retinaldehyde, 0.2% |
|---|---|
| Chain | One step from retinoic acid |
| Watch | Thinner evidence base |
0.2% looks small next to the 1% further down this page, and it is retinaldehyde — 1 conversion step from the active molecule rather than 2. That is the table above in a single product.
3,482 ratings is a thin evidence base against the 56,888 at the top of the page, which is the honest trade for a less common form. It is the sensible next step for someone whose retinol has stopped producing change.
Buy it if
- You want potency without a prescription
- Retinol has stopped producing change
Don't buy it if
- You are new to the category
Why 1% on 2 bottles means 2 different things
Two products can state the same retinol percentage and behave differently, because delivery decides how much reaches living skin. Encapsulation, the base the retinoid sits in, the pH of the formula and how the packaging excludes air and light all change the outcome.
Retinol also degrades. A serum in a clear jar has lost potency the customer paid for, which is why airless pumps and opaque tubes are worth more than a decimal place on the label.
So the number is a ceiling under laboratory conditions. What arrives at the receptor is a smaller and unpublished figure, which is why the 4.6 score on a formula stating no percentage sits level with the 4.6 on one stating 1%.
CeraVe Resurfacing Retinol Serum
56,888 ratings at 4.6, the deepest evidence base in the category, on a formula that states no percentage at all.
Current price shown on Amazon. We may earn a commission.
| Form | Retinol |
|---|---|
| Evidence | 56,888 ratings |
| Owners praise | Gentle on sensitive skin |
56,888 ratings at 4.6 makes this the most-evidenced retinol available, and it states no percentage anywhere. That omission is the section above made concrete — the brand is selling the formulation rather than the figure.
Owners repeatedly describe it as gentle enough for sensitive skin, which for a first retinoid is the specification that matters. The ceramide base is doing barrier work alongside the active.
Buy it if
- You are starting and want the least eventful introduction
- You want the most-evidenced option available
Don't buy it if
- You want a stated percentage to track
Retinisation lasts a fortnight and ends most routines
Retinisation is the adjustment period: dryness, flaking, redness and sometimes a worsening of breakouts for several weeks. It is expected rather than a reaction, and it is also the reason most people abandon the category.
The way through it is frequency rather than concentration. Twice a week for a fortnight, then every other night, then nightly if the skin tolerates it, is the standard progression.
Two techniques cut irritation without cutting results. Apply to dry skin, waiting 20 minutes after cleansing, because damp skin absorbs more and faster. And buffer with moisturiser underneath if the first fortnight is rough.
The Ordinary Retinol 0.2% in Squalane
The same formula at a fifth the concentration, which is the honest starting point and the reason the range exists in tiers.
Current price shown on Amazon. We may earn a commission.
| Form | Retinol, 0.2% |
|---|---|
| Base | Squalane |
| Use | Night only |
0.2% is the lower rung of a range that also sells 0.5% and 1%, and starting here is what the progression above actually looks like in a shopping basket.
Squalane as the base is well tolerated and the concentration is printed, so a step up is a measured decision rather than a guess. Night only, on dry skin, twice a week to begin.
Buy it if
- First retinoid, and you want to climb gradually
- You want the concentration printed on the bottle
Don't buy it if
- You have already tolerated stronger for a year
The Ordinary Retinol 1% in Squalane
1% is the largest figure on this page and it is retinol, which sits two conversion steps away from the active molecule.
Current price shown on Amazon. We may earn a commission.
| Form | Retinol, 1% |
|---|---|
| Base | Squalane |
| Watch | Irritation at this concentration |
1% is the largest number on this page and it is still retinol, 2 conversion steps from the active molecule. It is a serious concentration for that form and not a starting point.
19,823 ratings behind it, and irritation is the recurring theme in the reports at this strength. Come to it after months on 0.5% rather than as a first purchase.
Buy it if
- You have used retinol for months without irritation
- You want a stated concentration
Don't buy it if
- This is your first retinoid
Adapalene and tretinoin need 0 conversion steps
Adapalene is a synthetic retinoid that binds the receptor directly, so no conversion is needed. It moved to over-the-counter availability in the United States for acne, which makes it the strongest retinoid most people can buy without seeing anyone.
Tretinoin is retinoic acid itself and requires a prescription. It is the form with the longest clinical record for photoageing, and it is also the most irritating.
Neither is a cosmetic product, and both are worth a conversation with a clinician rather than a comparison of percentages. Adapalene is sold at 0.1% and tretinoin commonly at 0.025% to 0.1%, and neither figure is comparable to the retinol numbers above. Nothing on this page is medical advice.
Neutrogena Rapid Wrinkle Repair Retinol Serum
52,612 ratings at 4.4, the widest-distributed retinol here, sold on a timeline claim rather than a concentration.
Current price shown on Amazon. We may earn a commission.
| Form | Retinol |
|---|---|
| Evidence | 52,612 ratings |
| Watch | Irritation reports recur |
52,612 ratings makes this the most widely distributed retinol here, sold on a timeline claim rather than a stated concentration. Easy to replace in any pharmacy, which counts for a product used nightly.
Irritation reports recur, as they do across the category, and it carries fragrance — worth knowing for a leave-on night product on skin that is already adjusting to an active.
Buy it if
- You want a mass-market formula that is easy to replace
- A deep evidence base matters to you
Don't buy it if
- Fragrance in a night product bothers you
Sunscreen is part of the routine, not an accessory
Retinoids increase photosensitivity and they accelerate cell turnover, so the skin using them is younger at the surface and less defended. Using one without daily sun protection undoes the work it is doing.
Apply the retinoid at night, because the molecules degrade in ultraviolet light anyway. Then apply broad-spectrum SPF 30 or higher every morning, which what the SPF number measures sets out including how much of it to use.
That pairing is not optional. It is the whole reason the two articles link to each other.
How to buy without guessing
Pick the form for where you are: retinol to start, retinaldehyde when retinol stops producing change, adapalene or tretinoin only in conversation with a clinician.
Then check the packaging before the percentage, because an opaque airless tube protects the active and a clear jar does not. Of the 5 products here, 3 print a concentration and 2 do not, and the most-reviewed of them is in the second group. Products sorted by form rather than by number are in the retinoid shortlist. The gap between a printed figure and what actually reaches you is the same reading that genuine leather gets in a different aisle.