Ranking and Review Methodology

Best C Serum compares vitamin C serums using published product data. We do not test products on skin ourselves, and no score on this site is a dermatologist rating. This page explains exactly what our rankings are based on.

What the ranking uses

• Customer rating: the average star rating shown on a named retailer or brand page (for example Nykaa, Tata 1mg or the brand's own store).
• Review volume: the number of ratings on that same page.

Rating and review count must come from the same page on the same check. Price, bottle size and the checked date are recorded from that page too wherever it shows them.

How the score is calculated

Small samples can be misleading: a serum with five 5-star ratings should not outrank one rated 4.4 by 50,000 people. We therefore use a review-weighted average that pulls ratings with few reviews toward a neutral 4.2 out of 5:

score = (rating × reviews + 4.2 × 1000) ÷ (reviews + 1000)

Products are sorted by this score, then by review count. The "score out of 100" shown in some places is the same value multiplied by 20.

What is excluded

• Products without a sourced rating, or with zero reviews.
• Ratings checked more than 30 days ago. Older data stays on the product page, labelled with its check date, but drops out of rankings until it is re-verified.
• Products that are not individual vitamin C serums (creams, sunscreens, combos and supplements).

Missing data

When we cannot verify a detail such as vitamin C concentration, pH or skin-type suitability, the page says "Not disclosed" rather than guessing. Missing details do not raise or lower the ranking score. Skin-type and concern pages rely on product tags, which are only as complete as our product data; products without tags will not appear on those pages.

Where prices come from

Prices are the price displayed on the named source page on the date shown, usually the selling price rather than MRP. Prices and discounts change often and differ between sellers, so always check the retailer before buying.

Brand origin

The India Top 10 and Global Top 10 lists split products by where the brand is from, confirmed from a source. Being sold in India does not make a brand Indian.

Sponsorship and affiliate links

Sponsored placements are labelled "Sponsored" and have no effect on the score or order. Affiliate commissions do not affect rankings; see our affiliate disclosure.

Reviews on this site

Reviews submitted by visitors are moderated and shown separately on product pages. They are not mixed into the sourced retailer rating used for rankings.

How often rankings update

Rankings are recalculated every time the page loads, from the latest verified data. Product data is refreshed as part of our regular research; each product shows the date it was last checked.

Spotted an error? See our corrections policy.