What is the best form of vitamin d?

4 forms compared by what actually reaches your bloodstream. Absorption ranges from 60% to 95% — a difference that matters more than the milligrams on the label.

0 forms

0 best absorption %

0 average %

Ranked by absorption

Higher means more of the dose reaches you

Vitamin D3 (Calcidiol) 95 Vitamin D3 85 Vitamin D for Autoimmune Disease Support 85 Vitamin D2 (Ergocalciferol) 60

Short answer

Vitamin D3 (Calcidiol) absorbs best — 95%.

Fast-acting vitamin D therapy. Typical dose 5-20 mcg (medical supervision), about $80 a month. The cheapest option is Vitamin D3 at $8, but it only absorbs at 85%.

See Vitamin D3 (Calcidiol)

Every form side by side

Form	Absorbed	Safety	Per month	Dose	Evidence
Vitamin D3 (Calcidiol)	95%	6/10	$80	5-20 mcg (medical supervision)	B
Vitamin D3	85%	9/10	$8	1000-2000 IU	A
Vitamin D for Autoimmune Disease Support	85%	8/10	$25	2,000-6,000 IU daily	A
Vitamin D2 (Ergocalciferol)	60%	8/10	$15	2000-4000 IU	A

Head to head

6 comparisons

Vitamin D for Autoimmune Disease Support vs Vitamin D3 85% · 85% Vitamin D2 (Ergocalciferol) vs Vitamin D3 60% · 85% Vitamin D3 (Calcidiol) vs Vitamin D3 95% · 85% Vitamin D for Autoimmune Disease Support vs Vitamin D2 (Ergocalciferol) 85% · 60% Vitamin D for Autoimmune Disease Support vs Vitamin D3 (Calcidiol) 85% · 95% Vitamin D2 (Ergocalciferol) vs Vitamin D3 (Calcidiol) 60% · 95%

How to read this

Absorption is the share of the dose that reaches your bloodstream — the number that decides whether the milligrams on the label mean anything.
A cheaper form at half the absorption is not cheaper per unit delivered.
Safety here reflects tolerance at normal doses, not toxicity risk.
Evidence A means the form itself was studied, not just the parent compound.

Common questions

What is the best form of vitamin d?

Vitamin D3 (Calcidiol) — it absorbs at 95%, the highest of the 4 forms here. Fast-acting vitamin D therapy. Typical dose 5-20 mcg (medical supervision).

Which form of vitamin d is worst absorbed?

Vitamin D2 (Ergocalciferol) at 60%. It is usually the cheapest option, which is exactly why it ends up in budget products.

Is the expensive form of vitamin d worth it?

Compare per unit delivered, not per bottle. Vitamin D3 costs $8 a month at 85% absorption, Vitamin D3 (Calcidiol) costs $80 at 95%.

How much vitamin d should you take?

Doses differ by form: Vitamin D3 (Calcidiol) 5-20 mcg (medical supervision); Vitamin D3 1000-2000 IU; Vitamin D for Autoimmune Disease Support 2,000-6,000 IU daily; Vitamin D2 (Ergocalciferol) 2000-4000 IU.