How long should you tan?

How long to tan depends on two numbers

There is no single answer to “how long to tan”. The right time depends on how strong the sun is (the UV index) and how fast your skin burns (your skin type). Change either one and the minutes change.

The rule behind it is simple: dose = strength × time. If the UV index doubles, you get the same dose in half the time. That is why the same session lasts about twice as long at UV 3 as at UV 6, and about half as long at UV 11.

Your burn threshold is called the MED (minimal erythemal dose): the UV dose that just turns your skin pink. A good tanning plan stays well below it.

How long can I stay in the sun? Three examples

Here is how long unadapted skin takes to start burning, from the same formula the app uses:

• Fair skin at UV 5: burns after ~32 min. First session: 6:24.
• Medium skin at UV 7: burns after ~31 min. First session: 6:17.
• Very Fair skin at UV 9: burns after ~15 min. First session: 2:58.

Look at the gap. The burn time is not a target. It is the line you never want to reach. Staying “just under it” every day still adds up, and redness can arrive hours later.

For your own skin type and today’s UV, use the UV tanning calculator or open the page for your UV index, for example UV 5 or UV 8.

How long to tan on the first day

On day one, take one short session and stop. In Suntan Workout the first session is about 20% of your MED. That is close to what a professional tanning salon gives a first-time visitor.

It feels too short. Many people are surprised by how little it is. But your skin has not adapted yet, and you will not see how it reacted until the next day. Sunburn redness takes 12 to 24 hours to fully show.

So on your first day:

1. Check today’s UV index.
2. Find your burn time for your skin type.
3. Take about a fifth of it, split between front, back and sides.
4. Rest in the shade, then cover up or go inside.

How the time grows over the sessions

Tanning is gradual. Your skin builds colour and some protection from repeated small doses. Pushing past your threshold does not speed this up. It burns, then peels.

The Suntan Workout programme has 12 sessions:

• Build-up (sessions 1–8): the dose starts at 20% of your MED and rises about 18% each time, up to 64% on session 8.
• Deepening (sessions 9–12): 72, 80, 90 and 100% of your MED, only after the earlier sessions went without reddening.

So at the same UV index, session 8 takes a little over three times as long as session 1. The first four sessions are free in the app.

How long to tan per day, and why not every day

One session a day at most, and often not even that. Because redness shows up late, your skin needs time to “report back” before the next dose.

In the app the rest grows with the dose. It is about 23 hours after session 1 and about 48 hours after session 8, if your skin is fine. If it turned pink, the rest is half as long again. If it turned red, the rest doubles and the programme steps back.

A base tan does not change this much. It protects only about as much as SPF 2–3.

How long on each side

Do not lie on one side for the whole session. Split the sun time:

• Front: about 30–35%
• Back: about 30–35%
• Left side: 15–20%
• Right side: 15–20%

Then finish with a short shade rest, from 3 to 10 minutes depending on the session. Turning over on time matters more than the total. One side getting the whole dose is how people burn on “short” days.

No app? A rule of thumb

If you want to work it out yourself:

1. Find today’s UV index in a weather app.
2. Look up the burn time for your skin type and that UV in our UV pages.
3. Start with a fifth of that time, in total, for all sides together.
4. Stay well under the burn time on later days too. Increase slowly.
5. If your skin is pink the next day, do not go up.

Below UV 3 there is almost no tanning effect, so a long session in weak sun does little. On very bright days, choose the morning or late afternoon when UV is lower.

Lower the risk while you tan

No amount of planning makes UV harmless. Every exposure adds to skin cancer and skin-ageing risk. Keep sunscreen on your face, lips, ears and tattoos. If you have a photodermatosis, take light-sensitising medication, have had skin cancer or have many moles, talk to a doctor first.

If you get burned, get out of the sun and cool down. See a doctor for blisters, fever or a large area.

How the app calculates it live

Suntan Workout is a tanning timer app for iPhone, Apple Watch and Android. It reads the live UV index where you are, sets the session from your skin type and your step in the programme, and talks you through each position. Every 3 minutes it checks the UV again. If the sun gets stronger, it shortens the rest of the session so your dose stays the same.

For the bigger picture, read how to tan without burning.