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Welcome to this website!

You'll find everything you want to know about vitamin D right here.

Vitamin D can

Best way to get it? Sunlight! Nature's own prescription.

Next best way? Supplement vitamin D3.

It's better than Health Insurance and costs less than $2 per month!

Alex St Clair

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Your current vitamin D Status

Deficiency-correction or Maintenance dose?

Maintenance Dose for adults and children, by

Vitamin D intake from food

Vitamin D from cod liver oil

Vitamin D from sunshine

Vitamin D Calculator

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Vitamin D Calculator

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Estimate your Vitamin D

  • Required Dosage
  • Blood Level
  • From Sunshine

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Vitamin D Dosage

Each person needs a different dose

Vitamin D Dosage needs to be tailored to each person. Your own vitamin D status is the first thing to consider. If your body is already well stocked with vitamin D, you need less than someone whose vitamin D reserves are near empty.

Your vitamin D reserves depend on

Most people are not getting nearly enough sunlight and not taking enough vitamin D by mouth.

Their vitamin D status tends to be deficient for much of the year, perhaps rising to low-normal or normal by the end of summer.

You can see the different vitamin D blood levels and the corresponding vitamin D status in this table:-
 

25(OH)D Blood levels

Vitamin D Status

 ng/ml nmol/L
Severely Deficient 0-10 0-25
Deficient 11-20 26-50
Insufficient 21-32 51-81
Adequate 33-49 82-124
Optimum 50-65 125-163
High, but not toxic 66-100 164-250
Toxicity possible above 100 above 250


The optimum range is where vitamin D most effectively fights against many diseases. (See vitamin D benefits.)

To reach this level quickly, you could start by correcting your vitamin D deficiency, which involves taking a higher than normal dose for 60 days.

Then take the appropriate maintenance dose (tailored for you) to stay in the optimum zone.

How do you know if you are deficient?

By far the best way of finding your current vitamin D status, is to take a vitamin D blood test called the 25(OH)D test.

There are ways of estimating your vitamin D status without taking a blood test. See vitamin D levels.

Most people are vitamin D deficient, especially in winter and spring. 

Vitamin D3 maintenance dose

To remain in the optimum vitamin D range, a healthy 80 kg adult requires about 5000 IU (International Units) of vitamin D from all sources, every day. (If you think this is too high, see Vitamin D Overdose.)

Vitamin D sources include food, supplements such as multivitamins, and your own skin which makes vitamin D3 when directly exposed to strong sunlight.

So when you calculate your vitamin D dosage, you need to take into account how much sunlight shines on your skin.

Calculate your vitamin D dosage

On this web page there are two methods to arrive at your daily vitamin D maintenance dose:

  1. Table-look-up. (Your vitamin D dose in one minute.)
  2. Our VD3 Formula.

The Table-look-up is easy-to-use, and accurate enough to determine a practical vitamin D dosage for any person in good health, in one minute. (If you are not in good health, consult your doctor before supplementing vitamin D.)

The VD3 Formula is for people who want to aim for more precision, or to understand how the calculations work.

So let's start with the table look-up.

 

1. Table-look-up Vitamin D3 Dosage

Choose the column than corresponds to your body mass, and the row that best describes your current sun exposure habits. Then read off your vitamin D3 daily supplement dose in International Units (IU).

Sun exposure must be from strong sunlight (sun at least 30 degrees above the horizon) on bare skin, without sunscreen, and not through glass.

In winter, unless you live in a hot climate (e.g. tropical), select the "No Sun" group.

Vitamin D3 Dosage Table for Adults:
 

D3 Dose for adults Body Mass

Body mass (kg):

 50-70 71-90 91-120  > 120

Bodymass (pounds):

 110-155 156-199 200-264 > 265
How much strong sun? Vitamin D3 daily supplement (IU)
No Sun 3500 5000 6500 7500
A little on most days 3000 4000 5000 6000
Lots (outdoor type) 1500 2000 2500 3000
Very substantial, daily 0 0 0 0


The children's vitamin D dosage table works much the same way. Select the column according to the child's body mass (not by age).

Vitamin D3 Dosage Table for Children:
 

D3 Dose for children Body Mass (kg / pounds)
Body mass (kg): 5-10 11-20 21-35 36-49
Body mass (pounds): 11-22 23-45  46-77 78-109
How much strong sun? Vitamin D3 daily supplement (IU)
No Sun 500 1000 1800 2500
A little on most days 400 800 1500 2000
Lots (outdoor type) 200 400 800 1000
Very substantial, daily 0 0 0 0


Final step - for both adults and children

If you already take some vitamin D in a supplement (including a multivitamin, or cod-liver oil) subtract the amount of vitamin D in that supplement from the dose you just looked-up in the table.

That's it. You now have your personalized vitamin D dosage, adjusted for body weight and sun-exposure.

If you are currently in good health, you can take this dose with confidence. It will keep you from being vitamin D deficient and you will not be overdosing. But whether or not you will maintain an optimum level, or somewhat higher or lower, can only be determined by taking the blood test.

Our VD3 Formula described in the next section is less subjective, and more precise. But it will take you some time to do the calculations.

If you want to skip it, that's fine. Use the vitamin D dosage you have already looked up in the table. But first see our general information (including some precautions you need to know) about supplementing vitamin D.

 

2. Maintenance Dose by VD3 Formula

Our VD3 Formula uses these factors to calculate a vitamin D3 supplement dosage:

Because it takes body mass into account, the method is quite suitable for calculating a vitamin D supplement dose for all sizes of people, including very little people.

The method is quite simple:

  1. Start with the standard vitamin D dosage of 5000 IU from all sources, as needed to support optimum blood levels in a typical 80 kg adult.
  2. Adjust for your (or your child's) actual body mass.
  3. Subtract all the vitamin D you already obtain from sunshine, food, and any supplements you take, to arrive at the required vitamin D3 supplement dosage.

As you will see from the example below, the sunshine-sourced vitamin D is subtracted before the body mass adjustment because the tools you will be using to estimate vitamin D from sunshine do not take body mass into account.

VD3 Formula - examples

Here's an example calculation for a 50 kg person who currently gets enough daily sunshine to produce 1000 IU of vitamin D, obtains an average amount of vitamin D derived from food (200 IU), and takes a multivitamin providing 400 IU of vitamin D.
 

Vitamin D dosage calculation for 50 kg person 
Standard (80 kg adult) daily Vitamin D - all sources 5000
     Less vitamin D3 produced from sunlight (estimate) 1000-
Oral vitamin D required (by an 80 kg adult) 4000
Oral vit. D adjusted for body mass (previous line x 50/80) 2500
     Less Vitamin D obtained from food (estimate) 200-
     Less vitamin D present in your multivitamin 400-
Daily Vitamin D3 Supplement Dosage 1700 

We'll deal with how we estimate vitamin D intake from food and from sunshine in a moment.

Here are some more example calculations: an 80 kg adult, a heavier adult (120 kg), a teenager (40 kg) and an infant (10 kg).
 

Vitamin D dosage calculation - More examples
Body Mass (kg) 80 120  40 10
Standard daily vitamin D (all sources) 5000 5000 5000 5000
     Less D3 from Sunlight (estimate) 2000- 1000- 2000- 0
Oral vitamin D required by 80 kg adult 3000 4000 3000 5000
Adjust for mass: Previous x (Mass(kg)/80 3000 6000 1500 625
     Less Vitamin D from Food (estimate) 200- 300- 200- 100-
     Less Vitamin D from Multivitamin 400- 400- 200- 50-
Daily Vitamin D3 Supplement Dosage 2400  5300 1100 475 


So now you need to make your own calculation, similar to the examples above. Let's see how to estimate vitamin D from food and from sunshine.

How much of your vitamin D comes from food?

Estimating vitamin D intake from food is fairly easy. There are relatively few foods that naturally contain significant amounts of vitamin D, most of those being fatty fish (salmon, mackerel, herring, sardines, halibut, tuna etc). See Vitamin D Sources for examples of foods containing vitamin D.

If you carefully listed all foods you ate which contained vitamin D, and how often you ate them, you would arrive at a more exact figure, but it's probably not worth the effort. The average is less than 200 IU per day.

You might perhaps be 100 IU higher or lower than the average, but it won't affect your vitamin D supplement dose by much. In fact it's quite hard to get much more than 200 IU of vitamin D per day from food, every day, even in the USA where several foods are vitamin D fortified.

However, if you chose your diet to maximise foods naturally rich in vitamin D (mainly fatty fish), you might be able to do considerably better than average. To the extent that it is possible, this may be a better strategy than just supplementing vitamin D.
 

How much of your vitamin D comes from sunshine?

This is a little tricky. There are several variables. The most important are your skin-type, skin exposure percentage, exposure time, and the sun's angle above the horizon (which depends on your geographical latitude, the time of year, and time of day.)

And the last (and most variable) variable is you!

Everyone is different. So any tool for estimating a person's vitamin D production has to be used with caution.

But we have created one anyway, because we think you will find it useful and fun! It's called D-Estimator.

D-Estimator

D-Estimator is designed to show you the relationships between

for your skin-type, body-mass, age, and latitude (see infoplease) where you live.

D-Estimator is an Excel spreadsheet (very small -  downloads in a jiffy). It's free, with my compliments. Download D-Estimator.

Another useful tool is the Vitamin D from Sunlight calculator provided by the Norwegian Air Institute. It has just that one function, but is very detailed.

VD3 Formula - last step

Use one or both of these tools to estimate your current daily vitamin D production from sun exposure, then slot that estimate into your own VD3 Formula calculation.

Of course, if you're not getting any sun, for whatever reason, then it's really easy. Just enter zero vitamin D from sunshine.

If you do plan to get some of your vitamin D from sunshine (which is a really good idea, if you can) please read our Safe Sun Practices to Maximise Vitamin D.

Older people are known to be less efficient at making vitamin D from sunshine, so if you are older than about 40 and are relying on sunlight to provide much of your vitamin D, you may find your vitamin D blood level is lower than you expect. For more insight into this aspect of vitamin D production, download D-Estimator.

You should now be in a position to complete the VD3 Formula calculation to arrive at your own vitamin D dosage. Then all that remains is to check out the precautions and general information in our Supplementing Vitamin D page.
 

Vitamin D Dosage - Top