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How much vitamin D do you need a day?
The number, when the UK sun stops doing the job, who needs it all year and why it’s worth a thought for women. No scaremongering, promise.
Reviewed 30 October 2026 by the Spruce team. General information, not medical advice.
The short answer.
Adults and children over 1 need 10 micrograms (10µg, or 400 IU) of vitamin D a day. The NHS suggests everyone in the UK considers a daily 10µg supplement from October to March, when the sun isn’t strong enough for your skin to make it, and some people all year round. Don’t take more than 100µg a day unless your doctor tells you to.
One tap.
Is the sun doing
it for you?
In the UK, the sun is only strong enough for your skin to make vitamin D for half the year. Pick a month.
01Pick a month
Sunshine months assume you get outside with some skin uncovered. Some people need a supplement all year round.
02The verdict
Not enough sun in October.
From October to March the NHS suggests everyone considers 10µg of vitamin D a day.
One sachet, one glass
10µgvitamin D3 in Spruce Vitamin D + C
The NHS amount, in pineapple and grapefruit instead of a capsule.
The NHS says most people can make all the vitamin D they need from sunlight between late March or early April and the end of September, and suggests considering a 10µg daily supplement from October to early March. You can’t get too much vitamin D from sunlight, but always cover up or protect your skin before it starts to turn red or burn.
The official numbers.
Micrograms, IU
and limits.
Labels use micrograms (µg), plenty of tubs use international units (IU). One microgram is 40 IU.
Show the table
| Amount | Micrograms | IU | One Spruce sachet |
|---|---|---|---|
| NHS daily amount, adults and children over 1 | 10µg | 400 IU | 10µg D3, the same |
| Nutrient reference value (on labels) | 5µg | 200 IU | 200% NRV |
| Upper limit, adults | 100µg | 4,000 IU | A tenth of it |
| Upper limit, children 1 to 10 | 50µg | 2,000 IU | Made for adults |
Babies and young children have their own advice, so check the NHS vitamin D page ↗. If a doctor has prescribed a higher dose, follow their advice.
Worth a thought.
Why women,
especially.
Low vitamin D isn’t only a winter story, and it isn’t shared out evenly. UK doctors say it’s becoming more common in some age groups, particularly in girls and young women.
The simplest move is the one the NHS already suggests for everyone: a 10µg habit from October to March. If you’re worried about your levels, speak to your GP.
If you’re pregnant or breastfeeding, follow your midwife’s advice on supplements.
Not just a winter thing for some.
Who needs it
all year.
The NHS suggests 10µg a day all year round if you:
- Aren’t often outdoorsFor example if you work long indoor hours, are frail or housebound.
- Live in a care homeLess time outside means less chance to make it.
- Usually cover most of your skin outdoorsSunlight needs to reach your skin to do its job.
- Have dark skinFor example if you have an African, African-Caribbean or south Asian background, as you may not make enough even in summer.
Speak to your GP or pharmacist if you’re not sure what’s right for you.
Three ways in.
Sun, food
or supplement?
Tap a card to flip it.
Where Spruce fits.
Your daily D,
in a glass.
Pineapple & Grapefruit · about 75p a glassVitamin D + C10µg of vitamin D3 (200% NRV) and 160mg of vitamin C, with zinc and selenium, sugar free and sweetened with stevia. Vitamin D contributes to the maintenance of normal bones and muscle function and the normal function of the immune system. Vitamin C contributes to the reduction of tiredness and fatigue.Try Vitamin D + C ↗
A food supplement, not a substitute for a varied, balanced diet and healthy lifestyle. Made for adults. If you already take a vitamin D supplement, check the labels so your total stays under 100µg a day.
Less wondering. More sunshine.
Quick
questions.
The things people ask when they’re working out their vitamin D.
How much vitamin D do I need a day in the UK?
Adults and children over 1 need 10 micrograms (10µg) a day. The NHS suggests everyone in the UK considers a daily 10µg supplement from October to March, and some people all year round.
How many IU is 10 micrograms?
10µg is 400 IU. One microgram of vitamin D is 40 IU, so 25µg is 1,000 IU and the adult upper limit of 100µg is 4,000 IU.
Is 1,000 IU of vitamin D a day too much?
1,000 IU is 25µg, which is under the NHS upper limit of 100µg (4,000 IU) a day for adults. The NHS suggestion for most people is 10µg (400 IU). If a doctor has prescribed a different dose, follow their advice.
Should I take vitamin D all year round?
Most people make enough from sunlight between late March and the end of September. The NHS suggests 10µg a day all year if you’re not often outdoors, live in a care home, usually cover most of your skin outdoors, or have dark skin.
Can I get enough vitamin D from food?
It’s hard. Oily fish, red meat, egg yolks and fortified foods such as some breakfast cereals and spreads contain vitamin D, but the NHS says it’s difficult to get enough from food alone.
When is the best time of day to take vitamin D?
Whenever you’ll remember it. Plenty of people tie it to breakfast or the first drink of the day, so it becomes a habit rather than a chore.
Can I take Spruce Vitamin D + C with a vitamin D tablet?
One sachet has 10µg of vitamin D3. Added to a typical 10µg or 25µg tablet you stay well under the 100µg adult upper limit, but check the labels of everything you take.
Should I get my vitamin D tested?
Doctors don’t routinely test vitamin D. If you’re worried, or think you might be at higher risk, speak to your GP.