Sunscreen shelves in India run from SPF 15 to SPF 50 PA++++, and the pricing usually implies that protection climbs in step with the number. It does not. The SPF figure measures something narrower than most people assume, and the biggest variable in real-world protection is not printed on the pack at all. Once you know what the label is actually saying, the choice becomes fairly simple.
What the SPF number actually measures
SPF stands for sun protection factor, and it is measured against UVB, the shorter wavelengths that burn. In the standard test, sunscreen is applied at a set thickness (two milligrams per square centimetre, considerably more than most people ever wear) and testers compare how much UV the protected skin can take before reddening against bare skin.
The useful way to read the number is as a fraction let through. At test thickness, SPF 15 lets roughly one unit of burning UV in fifteen reach the skin. SPF 30 lets through about one in thirty, and SPF 50 about one in fifty.
SPF 15 vs SPF 30 vs SPF 50
Read as fractions, the steps stop looking evenly spaced. Moving from SPF 15 to SPF 30 halves what reaches the skin, a genuine jump. Moving from SPF 30 to SPF 50 narrows an already small remainder, from one part in thirty to one part in fifty. That is a real improvement and a much smaller one than the packaging war suggests.
On the test bench, that argues for SPF 30 and not much further. In practice there is a complication covered below: almost nobody applies sunscreen at test thickness. A higher number on the label is less a promise of near-total protection and more a margin of safety for the thin coat most people actually wear.
What the PA rating means
The SPF number says nothing about UVA. Those are the longer wavelengths: they penetrate deeper into skin, they are present from morning to evening in every season, and they pass through window glass. UVA is also the main driver of pigment darkening and a large share of long-term sun damage to skin structure.
The PA system, which originated in Japan and is common on Indian shelves, grades UVA protection from PA+ up to PA++++, based on a test of persistent pigment darkening. More plus signs mean more UVA protection. If a pack carries no PA rating, look for the words "broad spectrum", which promise UVA coverage without grading it.
For anyone whose main concern is tone, which covers dark marks, tanning and melasma, the PA side of the label matters at least as much as the SPF side. Pigment responds to UVA doses far below anything that burns.
Why deeper skin tones still need it
Melanin is genuinely protective. Skin rich in it burns far less readily, which is why sunburn is a smaller part of life in most of India than in northern Europe. But the protection is partial, and it is mostly protection against burning.
Darkening is another matter. Melanin-rich skin tans readily, marks readily, and holds pigment longer once a mark has formed. The concerns that bring most Indian readers to a sunscreen article, uneven tone, marks that linger after breakouts, melasma, tanning, are pigment responses with a strong UVA component. Whatever tone-evening work a routine does during the week, unprotected UVA quietly undoes at the weekend; does sunscreen remove dark spots walks through that dependency in detail. On deeper skin tones the case for sunscreen rests on pigment and long-term skin health, not on the risk of burning.
The amount matters more than the number
Every SPF figure assumes test thickness. Studies of real use find people applying somewhere between a quarter and a half of that, and protection does not fall gently with thin application, it falls steeply. A thin scrape of SPF 50 can deliver less real protection than a full layer of SPF 30.
The practical dose for face and neck is about two finger lengths of product, squeezed along the index and middle fingers. It feels like too much. That is the tested amount. Reapplication is the other half of the job: the film rubs off, sweats off and degrades in sunlight, so outdoor hours need a fresh layer every two to three hours. How to use sunscreen on your face covers the routine step by step.
So which SPF is enough
For ordinary indoor-and-commute days, a broad-spectrum SPF 30 with PA+++ or better, worn at the full amount, is enough. For long outdoor hours, step up to SPF 50 PA++++ and add shade, clothing and reapplication, because sunscreen alone was never meant to carry a full day of sun.
Texture belongs in the decision too. A sunscreen that feels heavy or turns your skin grey will be skipped by Thursday, and a skipped SPF 50 protects less than a worn SPF 30. If breakouts or a grey cast are what put you off, does sunscreen cause breakouts covers how to choose around both.
Where Cham stands
Cham does not sell a sunscreen, so this article has no bottle to steer you toward. The Cham range covers cleansing, moisturising and evening the look of tone, and all of that work assumes a sunscreen from some other shelf is on duty each morning. Pick a broad-spectrum SPF 30 or higher with a PA rating you can actually find on the pack, apply two fingers' worth, and renew it when you are out in the sun. The layer matters more than the number printed on it.
