How Should I Protect My Skin Today?
Sun protection depends far more on today’s UV Index than on skin tone: once the UV Index reaches 3, broad-spectrum SPF 30 or higher, shade and covering up are worth using at every skin type. This calculator estimates how your skin responds to sun, turns today’s UV Index into specific guidance, and works out how much sunscreen a trip needs.
Your skin
Type III Light–medium tone
Estimated skin type. Based on skin tone alone. Sun response can improve this estimate.
Your answers do not map neatly to one phototype. We've used the more sun-sensitive estimate for the protection guidance.
Improve estimate
UV Index today
6 High
- 0–2 Low
- 3–5 Moderate
- 6–7 High
- 8–10 Very High
- 11+ Extreme
Today’s figure is in most weather forecasts and phone weather apps. It peaks around the middle of the day, and it is not the same thing as temperature.
Your protection
UV 6, High. Estimated Type III. Broad-spectrum SPF 30+.
Broad-spectrum SPF 30+
UV 6 · High · Estimated Type III
- Sunscreen
- Broad-spectrum SPF 30 or higher, water resistant, applied generously.
- Reapply
- About every 2 hours while you are outdoors.
- Also
-
- Hat
- Sunglasses
- Covering clothing
- Shade
- Midday
Some medicines, skin conditions, recent treatments, altitude, snow and water reflections can increase sun sensitivity or the ultraviolet you are exposed to. If you take a photosensitising medication or have a skin condition, follow advice from your clinician or pharmacist.
How much sunscreen do I need?
Most cabin-baggage limits are 100 ml a container — the same rule as the American 3.4 US fl oz, which is really 100.55 ml. Some airports now allow more.
For babies under 6 months, prioritise shade and protective clothing. Follow local medical guidance about sunscreen use on small exposed areas when adequate shade and clothing are unavailable.
1,638 ml
55 US fl oz
Pack 9 × 200 ml (6.8 US fl oz) bottles — about 162 ml spare.
How that was worked out
| 2 adults | 2 × 30 ml × 3 applications a day × 7 days | 1,260 ml 42.6 US fl oz |
|---|---|---|
| 1 child | 1 × 18 ml × 3 applications a day × 7 days | 378 ml 12.8 US fl oz |
| Total | 1,260 ml + 378 ml | 1,638 ml 55.4 US fl oz |
| 9 bottles | 1,638 ml ÷ 200 ml, rounded up | 9 |
Choosing an SPF
Broad-spectrum SPF 30 or higher is the practical baseline whenever sun protection is called for, and it is what this calculator recommends at every estimated skin type. Broad-spectrum matters as much as the number: it means the product filters UVA, which drives ageing, as well as the UVB that reddens skin.
The figure on a bottle describes performance under a thick, even test layer almost nobody reproduces on a beach, so a higher factor is best understood as headroom for imperfect application. Sunscreen reduces the ultraviolet reaching your skin; it does not buy extra exposure.
How the skin-tone slider works
The slider is a colour control, not a diagnosis. Dragging it estimates your Fitzpatrick phototype from tone alone, which is enough to put a real answer on screen straight away — but phototype is about behaviour in ultraviolet light rather than about colour.
That is why “Improve estimate” asks two short questions about burning and tanning, and why those answers replace the tone estimate rather than being averaged into it — DermNet defines the phototype as a classification of skin “by its reaction to exposure to sunlight”. Where the two disagree by more than one type, the calculator takes the more sun-sensitive and says so.
The six Fitzpatrick phototypes
| Type | Typical tone | How it responds to sun |
|---|---|---|
| Type I | Very light tone | Usually burns very easily and does not tan |
| Type II | Light tone | Usually burns easily and tans only slightly |
| Type III | Light–medium tone | May burn at first and tans gradually |
| Type IV | Medium tone | Burns minimally and tans easily |
| Type V | Deep tone | Rarely burns and tans readily |
| Type VI | Very deep tone | Burning is uncommon, with deeply pigmented skin |
What the UV Index means
The UV Index measures ultraviolet strength at ground level on an open-ended scale starting at zero. The World Health Organization groups it as Low, Moderate, High, Very High, Extreme, and recommends protection from 3 upward — the threshold this calculator uses.
It peaks around solar noon, rises in summer, nearer the equator and at altitude, and reflects off water, sand and snow. It is not temperature — a cool, bright spring day can carry a higher index than a humid overcast one, which is the most common reason people are caught out.
What to do at each UV Index
| UV Index | Category | What to do |
|---|---|---|
| UV 0 | Low | Nothing mandated for brief exposure |
| UV 1 | Low | Nothing mandated for brief exposure |
| UV 2 | Low | Nothing mandated for brief exposure |
| UV 3 | Moderate | SPF 30+, hat, sunglasses, covering clothing, shade |
| UV 4 | Moderate | SPF 30+, hat, sunglasses, covering clothing, shade |
| UV 5 | Moderate | SPF 30+, hat, sunglasses, covering clothing, shade |
| UV 6 | High | SPF 30+, hat, sunglasses, covering clothing, shade |
| UV 7 | High | SPF 30+, hat, sunglasses, covering clothing, shade |
| UV 8 | Very High | SPF 30+, cover up, and keep midday exposure short |
| UV 9 | Very High | SPF 30+, cover up, and keep midday exposure short |
| UV 10 | Very High | SPF 30+, cover up, and keep midday exposure short |
| UV 11+ | Extreme | SPF 30+, cover up, and keep midday exposure short |
How much sunscreen to apply
The American Academy of Dermatology puts it at roughly 30 ml for an adult to cover exposed skin in one application — about a shot glass, or half a teaspoon each to the face, neck and each arm, and more to each leg. Using less is the usual reason a high factor underperforms.
Reapply about every 2 hours outdoors, and again after swimming, towelling dry or sweating heavily. Water resistance is stated on the label in minutes of immersion, so follow the bottle rather than a rule of thumb.
Bottles to pack, by party and trip length
| Who is going | 3 days | 7 days | 10 days | 14 days |
|---|---|---|---|---|
| 1 adult | 1 | 3 | 3 | 5 |
| 2 adults | 2 | 5 | 6 | 9 |
| 2 adults, 1 child | 3 | 6 | 8 | 11 |
| 2 adults, 2 children | 3 | 7 | 10 | 14 |
Darker skin and UV
Deeply pigmented skin reddens less readily, and that is a genuine difference rather than a myth. It is not immunity: ultraviolet damages skin at every phototype, and the Skin Cancer Foundation reports that in people of colour skin cancer is often found later, when it is harder to treat.
So the guidance never softens because the slider was dragged towards the deep end. Your estimated phototype changes the sentence of context beside the result; the UV Index decides the result itself.
Common questions
What SPF should I use?
Broad-spectrum SPF 30 or higher, water resistant, whenever sun protection is needed. Protection depends much more on the UV conditions you are in, and on applying enough product, than on choosing a bigger number — so this calculator recommends the same baseline at every estimated skin type. “Broad-spectrum” is the wording used in the United States and Australia; a European bottle may instead carry a UVA mark inside a circle, and one bought in Japan or Korea is graded PA+ to PA++++. All three describe protection against UVA as well as the UVB the SPF number measures.
Can skin colour determine my Fitzpatrick type?
No. Skin tone gives a useful first estimate, but the Fitzpatrick phototype describes how skin reacts to ultraviolet light: how readily it burns, and how it tans. That is why the slider here is only a starting point, and why the two sun-response questions override it rather than being blended into it.
Can SPF tell me how long I can safely stay in the sun?
No, and this calculator deliberately does not try. Multiplying a factor by how quickly skin reddens assumes a thick, even layer that stays put — and measured in real use, people apply only about 20 to 50 per cent of the amount an SPF is tested at, so any figure built on that assumption is optimistic by a wide margin. Most sunscreen calculators publish one anyway. This one treats a bottle as something that reduces the ultraviolet reaching you, not as extra time.
How often should sunscreen be reapplied?
About every 2 hours while you are outdoors, and again after swimming, towelling dry or sweating heavily. Water resistance is stated on the label as a number of minutes in water, so the bottle in your hand is a better guide than any general interval.
How much sunscreen does an adult need?
Roughly 30 ml for full exposed-body coverage in a single application — about one US fluid ounce, or a shot glass. Authorities differ at the margin: that is the American Academy of Dermatology's figure, while the NHS puts it at 6 to 8 teaspoons and Cancer Council Australia at 7, which is 30 to 40 ml. This calculator uses the lower end, so treat its total as a floor rather than a target. It assumes about 18 ml for a child, and shows the arithmetic.