The Vitamin C content on Ujala's Vitamin C Serum comes from fruit extracts, so we don't give our serum a specific vitamin c percentage. This is because the amount of Vitamin C between individual fruits varies (eg. Every lime is completely different to the next). More important than the percentage, is the long term availability of Vitamin C in our serum.Generally, the Vitamin C content on mainstream serums comes from a synthetic purified form of ascorbic acid. Studies have shown that, typically, the percentage of synthetic Ascorbic Acid (vitamin c), used in the vast majority of vitamin c serums, decreases in 20-80 days. This means a product may be batched with a high percentage of Vitamin C but that amount will steadily decrease over a short period of shelflife. Whereas, the naturally-occurring Vitamin C inside our serum is stable and holds steady for over 2 years.