Low-cost salicylic acid products should be compared as leave-on products, with the observed bottle size beside the price. These five options include inexpensive serum headlines and larger toner quantities. Our captures support several unit-cost calculations, but not every selected variant, so the list distinguishes documented value from an unsupported universal cheapest claim.

The same 2% headline does not make the formulas interchangeable. Vehicle, additional acids and shipping can change the decision. Peach Slices and Naturium supply useful 120 mL reference points; The INKEY List supplies a confirmed 30 mL pair. The Ordinary’s lower observed dollar headlines still require selected-volume confirmation before a precise unit comparison.

The Ordinary Salicylic Acid 2% Solution — leave-on bha serum

The Ordinary’s $6.70 headline is the lowest observed bottle price among these five, before shipping and tax. That limited claim is different from the lowest unit cost or lowest delivered total. Its selected quantity was not recovered clearly. It remains a sensible candidate to investigate when minimizing the initial purchase, provided you verify the bottle and avoid buying extras merely to reach free delivery.

The Ordinary Salicylic Acid 2% Solution is a water-based leave-on formula positioned for acne-prone skin. It is distinct from both the anhydrous version and the rinse-off masque. The shared 2% headline does not erase differences in vehicle, product instructions or intended format, and it cannot serve as a guaranteed sensitivity rating.

The official US capture shows $6.70 and free shipping on orders above $25. The selected volume is not exposed unambiguously in the text, so we do not assign a price-per-milliliter winner. A low bottle headline remains useful, but buying extra products to pass a delivery threshold may increase the total you actually spend.

Related reading: Salicylic acid: acne treatment or smoothing ingredient? · CoreAge Rx Pore Favor review

The Ordinary Salicylic Acid 2% Anhydrous Solution — leave-on bha serum

The anhydrous solution’s $7.50 headline offers a different vehicle at a similarly small purchase commitment. Its squalane-based format is not just the water-based solution in another package. Cost alone cannot choose between them, and the capture again leaves selected volume open. Evaluate the base and actual checkout total rather than declaring two equal-strength formulas equivalent by price.

The Ordinary Salicylic Acid 2% Anhydrous Solution is a water-free leave-on formula with a squalane-based emollient vehicle. The brand positions that base differently from its water-based solution. That is a product-specific design claim, not proof that every reader with sensitive or dry skin can use it without irritation or combine it with other exfoliants.

The official US page shows $7.50 and free shipping above $25. The selected bottle volume is unresolved in the capture; confirm it before a unit-cost calculation. This is a one-time anhydrous formula price, not an assumed month of treatment or evidence that its emollient base is clinically equivalent to a competitor.

Peach Slices Acne Exfoliating Toner — leave-on acne toner

Peach Slices provides $10.99 for 120 mL, the lower verified unit-price pair among the two 120 mL toners here. That makes it a useful larger-bottle budget reference. It also includes additional acids, so the unit arithmetic is not a tolerability ranking. Confirm shipping on the single item and consider whether this formula duplicates exfoliants already in your routine.

Peach Slices Acne Exfoliating Toner is a 120 mL leave-on toner with 2% salicylic acid plus glycolic and lactic acids. The page attributes some clinical language to ingredient and supplier studies and separately describes consumer work on the acne collection. Those evidence types do not establish an independent head-to-head trial of this bottle against another brand.

The official page shows $10.99 for 120 mL, approximately $0.09 per mL before tax and shipping. That is an observed one-time toner price, not a complete checkout total or an assumed 30-day supply. No unverified subscription or bundle discount is applied; the three-step system is a different, larger purchase.

Compare the options in top 5 salicylic acid creams & treatments or read Creams versus liquids and gels.

The INKEY List Beta Hydroxy Acid — leave-on bha serum

The INKEY List shows $14 for 30 mL and makes the shipping issue unusually visible. A delivery charge beginning at $7.95 changes the single-bottle total substantially. Its hyaluronic-acid support and serum format may still be the reason to choose it. Compare the landed purchase rather than giving a larger cart credit for free shipping when it includes products you did not need.

The INKEY List BHA Serum is a 30 mL leave-on acne treatment listing 2% salicylic acid and 1% hyaluronic acid. It performs a treatment step rather than cleansing the face. A hydrating ingredient does not cancel every irritation risk, and the current Drug Facts or product directions should be read with any other acne medication.

The direct capture shows $14 for 30 mL, approximately $0.47 per mL before tax and delivery. The page advertises US shipping from $7.95, with some states at $8.95, and free shipping above $40. For a single bottle, the shipping charge can materially change its apparent advantage over another low-priced treatment.

Naturium BHA Liquid Exfoliant 2% — leave-on bha exfoliant

Naturium shows $19 for 120 mL, providing another verified larger leave-on-liquid calculation. Its observed unit cost is higher than Peach Slices in this snapshot, but the formulas differ. A bigger bottle can be useful if you want that exact product; it is not automatically economical if you discontinue it after discomfort or already have a leave-on acid that works.

Naturium BHA Liquid Exfoliant 2% is a 120 mL leave-on liquid. It should not be confused with Naturium’s salicylic-acid body wash or 360-degree body spray. Keeping those formats distinct prevents a misleading price comparison and avoids applying assumptions about a rinse-off product to a leave-on acid step with different label instructions.

The current official price is $19 for 120 mL, approximately $0.16 per mL before tax and shipping. This is a one-time bottle listing, with no verified subscription condition applied here. Compare with another leave-on liquid by confirmed quantity, and keep the separate body wash and body spray out of the same unit-price category.

How these five answer this particular question

The fair numerical statement is narrow: among the captured 120 mL toner pairs, Peach Slices has the lower observed product price; among the five bottle headlines, The Ordinary’s water-based solution has the lowest observed starting amount. Neither establishes the cheapest suitable treatment in the whole market. Shipping, tax, selected size and formula differences prevent a universal winner, and no presumed monthly bottle lifetime is used.

Before choosing an option

Keep a budget for the complete routine, including moisturizer and sunscreen where appropriate. Read current labels, return terms and any recurring purchase option before checkout. If acne is persistent or severe, a lower-priced bottle is not a substitute for the right assessment. This shortlist compares transparent retail facts and category tradeoffs, without promising that a cheaper product yields the same response or providing individualized frequency instructions.

Sources and verification

Official pages establish product facts and provider claims. Clinical and regulatory sources answer separate evidence questions. Checked October 1, 2026. No medical reviewer is credited for this article.