What retinal is, and why the rung matters more here
Retinaldehyde sits one conversion step from retinoic acid, the form that actually acts on skin. Retinol sits two. That single step is why a retinal and a retinol at the same printed percentage are not equivalent products, and why getting the rung wrong on a retinal is more punishing than getting it wrong on a retinol.
It also means the published figure carries more information than usual. On a retinol you are a step further from the active and a formulation can blunt or sharpen the effect considerably. On a retinal the number is closer to the thing you care about, which is precisely why a twenty-fold gap between two products is a real twenty-fold gap and not a labeling artifact. Our retinol vs retinal comparison works the chemistry through properly.
The two products, side by side
Medik8 Crystal Retinal 1
A 30 ml night serum at 0.01% retinaldehyde, with hyaluronic acid and vitamin E in the base per the listing. What you are buying is not potency — it is the lowest genuinely-labeled rung available, inside a numbered range you can climb on purpose. If you intend to use a retinoid for a decade, starting on a planned ladder rather than an improvised one is a defensible reason to pay more, and Medik8 publishing every figure in that ladder is the reason we rate it as the starter here.
The honest cost is the price at every rung, not just this one. The ladder is premium all the way up, and the step from 1 to 3 to 6 is another purchase each time.
The Ordinary Retinal 0.2% Emulsion
A 15 ml light emulsion at 0.2% retinaldehyde — the cheapest route into retinal by a wide margin, and one of very few products in the whole category that prints its figure. The base layers easily under a moisturizer. The two things to hold in mind are that 0.2% retinal is a high rung and not a starting point, and that 15 ml is a small bottle, so the price per use is less dramatic than the price per bottle.
Cost per millilitre, which is the comparison people actually want
Work it out from the live prices in the table above rather than from the shelf price: Medik8 is 30 ml, The Ordinary is 15 ml, so the bottle sizes differ by a factor of two before the prices are even considered. The Ordinary is still substantially cheaper per millilitre at every price we have seen. It is also twenty times the stated strength, which is the reason the saving is not the headline.
Which should you buy?
If you have never used a retinoid at all
Neither. Start on a retinol, establish that your skin tolerates a vitamin A derivative, and come back. The beginner roundup is the right page for a first bottle, and when to start retinol covers the question underneath it.
If you use retinol comfortably and want to step up
The Ordinary, and treat it as the step up it is: two nights a week for the first month, a pea for the whole face, moisturizer over the top. Our guide to stepping up sets out the tests that say you are ready, and the published escalation logic behind them.
If you have reacted badly to retinoids before
Medik8 rung 1, or the Avene Retrinal 0.05% in the table above if you would rather have a cream than a serum. Both are low, both print their figure, and both give you somewhere to go afterwards. The sensitive skin roundup ranks on irritation risk rather than strength.
If you want one retinal for face, neck and chest
Neither — 30 ml and 15 ml are both face-sized. The Naturium Retinaldehyde 0.10% in the table is 50 ml and explicitly sold for the larger area, and our neck and chest roundup explains why size outranks strength once you go below the jaw.
Storage matters more with retinal
Retinoids degrade with light and heat, and the published stability work on commercial retinoid cosmetics found losses ranging from none at all to total over six months at room temperature, with light the worse of the two stressors. That is a reason to keep either of these closed, out of the bathroom window and away from the shower, and a reason not to buy the biggest bottle you can find on the theory that it will last.
It is also why neither of these numbers describes what is in the bottle in month eight. The figure is what was formulated, not what survives your bathroom. Our guide to retinol shelf life goes through the packaging hierarchy.
The verdict
Medik8 for your first retinal, The Ordinary for your fourth. The brands are not competing for the same buyer, whatever the search query implies: one sells the bottom of a published ladder at a premium, the other sells near the top of that same ladder for the price of lunch. The mistake to avoid is reading “1” as stronger than “0.2%” because it costs four times as much.
