The UV Index is calculated on a scale from 0 to 10, with the latter representing the highest risk. In today’s guide, we will learn to understand the various UV Index numbers, how each level influences tanning and much more.
The main reason why this UV index exists is to help you understand how risky (or safe) it is to spend time out in the sun.
The higher the UV index, the less time you should spend in the sun without additional protection (like sunscreen).
When the UV index is really high, even if you’re wearing a strong sunscreen, you should still spend minimum amounts under the sun. We’ll learn why and how long you can stay out depending on the UV index today.
Now, to better understand the correlation between UV Indexes and tanning as well as the potential harm the sun can cause depending on these values, we’re listing below the UV index scale in an easy to read table.
UV INDEX SCALE
| UV Index | Meaning |
|---|---|
| 0 – 2 | Lowest values, suggesting minimal risk. You can spend more time out in the sun (up to 1 hour). It’s still recommended to wear a hat and a SPF 15+ sunscreen to be as safe as possible. |
| 3 – 4 | These are still low values that shouldn’t force you to skip beach day. Wear a hat and a sunscreen with SPF values of around 15-30 (or more). You can spend up to 1 hour in the sun if you take all precautions. |
| 5 – 6 | Medium values. A hat and sunscreen are a must (SPF 30+). Don’t spend more than 30 minutes in the sun. Look for shaded areas and stay there as much as possible. |
| 7 – 8 | These values are starting to be on the high end. Limit exposure time to a maximum of 20 minutes. Wear a hat and use a sunblock with SPF 50+ and stay inside between 11 AM – 4 PM. |
| 9 – 10 | Very high levels, so limit exposure to 15 minutes at most. Hat and SPF 50+ sunscreen are mandatory for maximum safety. You should also stay inside between 10 AM – 5 PM. |
What is a safe level of UV Rating?
As you can see in the table above, the safest levels of UV ratings are between 0 and 2. UV Index levels of 3 and 4 are also considered generally safe as long as you wear a hat, sunscreen and don’t spend more than 1 hour in the sun.
Even with these lower values, although it’s safe to spend more time directly under the sun, don’t overdo it and try to limit exposure to a maximum of one hour.
Being in the shade, under an umbrella at the beach, for example, and wearing the proper sunscreen allows you to spend more time outside without having to worry too much about overexposure.
Also pay special attention to kids! Don’t let them spend too much time under the sun either. It might be all fun and games if you’ve carefully planned your trip, but safety should always come first!
What UV index values are best for tanning?
Unfortunately, sunbathing is not considered healthy (read an article on Harvard about this if you don’t believe me) and there is no such thing as a “healthy tan” (as the FDA warns).
Tanning – getting that beautiful brown shade that so many people love – actually represents skin damage.
When you expose your skin to UV radiation by sitting out in the sun, your body starts producing melanin, trying to stop further skin damage. And it’s this melanin that causes the darker skin tone aka tanning.
Even though most people do know that tanning is not healthy, they still prefer to take the risk (which is, in most cases, minimal if done correctly) for that beautiful, sun-kissed color.
In order to keep these risks as low as possible, you should know that some UV index values are safer for tanning than others.
The best UV index for healthy tanning is anything between 2-4. You should still wear a sunscreen of SPF 15+ (ideally 30) and not spend more than 60 minutes in the sun. After this, you risk overexposure and getting your skin burned.
Some people, depending on their genes, will get sunburn faster (45 minutes or less) even on a lower UV index, while others can safely spend some more time under the sun. So take the 60 minutes as an average, not a rule and always listen to and look at your body!
While the UV index between 2 to 4 is ideal for healthy tanning if done right, it doesn’t mean that you can’t get a tan on other levels too. You can, but this happens much faster.
For example, spending some 15 minutes under the sun when the UV index is between 5-6 will result in a tan (while 30 minutes are enough for you to get sunburn), while an UV index of 7-8 will get you tanned and sunburned faster.
In all cases, you should wear extra protection (a hat, sunglasses and a good, high-numbered SPF sunblock).
Also, if the UV index levels are too high, you should limit time spent outside and stay as much as possible in the shade.
In other words, if the UV index is high, you will tan faster and if the UV index is low, it will take you longer to get that tan you always wanted.
What UV index should you wear sunscreen?
It is recommended to wear sunscreen even on low UV indexes (1-2), but in this case a SPF 15+ one should be enough.
A SPF of at least 30 should be used when the UV index is at level 3 and above and you should switch to a SPF 50+ once the UV Index reaches level 7 and above.
Remember that even when wearing sunscreen, you shouldn’t spend more than the recommended time in the sun!
Also, you can’t have too much sunscreen. So if you decide to use a SPF 50 cream when the UV index is 2, your skin will be even better protected (but you won’t get tanned as fast as a result).
How long does it take to tan if the UV index is low?
An UV index of 1 to 2 is considered low. 3-4 is considered moderate, but many people also call it low. So we’ll talk about both values and how long it takes to tan in these conditions.
If the UV index is 1 or 2, getting a sunburn is very unlikely if you use precaution. Also, this means that getting a tan will take longer than if the index is 7, for example. The skin will start to get burned after around 60 minutes.
Spend around 10 minutes on each side (40 minutes total) when the UV index is low in order to get tanned evenly. You can spend more time in the sun, but don’t exceed the recommended 60 minutes mark, otherwise you risk getting a sunburn.
You will tan faster under moderate to low UV index (3-4), although most people can still safely take 40 minutes total, with 10 minutes of sun on each side.
In all cases, don’t forget to take all necessary precautions. This means that you should wear a sunscreen (at least 15 SPF, although most experts recommend 30+ even when the UV index is low). You should also wear a good hat and sunglasses.
How long does it take to tan on a cloudy day?
As we discussed already, your genes influence the amount of time required to get a tan. Some people can last longer under the sun than others.
While the clouds do filter out some UV radiation, they don’t block it entirely. Depending on the color of the clouds, they will allow anything between 30% to 90% of the sun rays to pass through. Grey clouds filter more than white, fluffy ones.
Deciding how long does it take to tan on a cloudy day depends on a lot of factors. You should still check the UV Index forecast in your area, as these will usually take clouds in consideration.
If the UV index is 2-3 when it’s cloudy, spending some 10 minutes one each side for a total of 40 minutes should allow your skin to get tanned.
Remember that even when it’s cloudy, you should still wear sunscreen and your regular protection!
Best UV Index for Vitamin D
Our body creates vitamin D when the skin is exposed to UV from sunlight (mainly UVB radiation). When the UV Index is 3 and above, our body only needs several minutes of sun exposure each day in order to produce the required amount of Vitamin D.
Lighter skinned people can get the necessary amounts in as little as five minutes of sun exposure per day (such as walking outside), while darker skinned people may need up to 20 minutes each day, according to Science Learning Hub.
Remember, the UV index must be 3 or above for our bodies to produce Vitamin D! Since these numbers are easily met in most parts of the world from spring to autumn / fall, simply being outside for as low as 20 minutes per day will give you the required amount of Vitamin D.
Conclusion
We’ve learned everything about the UV radiation and tanning, but also checked that useful UV index chart that tells you how safe (or unsafe) it is to be outside, depending on the UV index of the day.
Simply because UV radiation is considered unhealthy, you shouldn’t stop going outside as we do need that (not only for a beautiful tan!)
Instead, make sure to spend no more than the recommended amount of time under the sun based on the UV Index levels and also wear protection – a hat, sunglasses and appropriate clothing, as well as a sunscreen with a SPF of at least 30.
If you have additional questions, concerns or comments, let me know by commenting below.
Daniel is a gear freak when it comes to hiking, climbing and camping. He went to REI Outdoor School to meet new people and learn best practices. Don’t even try to argue with him about the latest backpack or ice axe, he tried most of them. Daniel’s dream is to climb Mount Everest.