How much does Vitamin D3 build up with daily dosing?

At steady state on a daily schedule, the model's level is about 22.14 times what one dose gives, and it swings about 1:1 between the peak and the trough before the next dose. Longer gaps between doses mean less build-up and a bigger swing.

Is this chart my actual Vitamin D3 level?

No. It is a modeled estimate from a published half-life, using the same one-compartment model as the Dose Track app. Real levels vary with body weight, food, kidney and liver function and other factors, and only a lab test measures them. It is not medical advice.

Vitamin D3 Half-Life: Peak and Steady State Chart

Q: When does Vitamin D3 peak after a dose?

Blood levels peak about 14 days after a dose by mouth, according to Armas LA et al. 2004. Individual timing varies with food, the amount and the person.

Q: How long does Vitamin D3 take to reach steady state?

About 75 days (~10.7 weeks) of regular dosing at the same amount and interval, which is 5 half-lives. With a half-life of about 15 days, levels reach about 50% of steady state after 15 days and about 90% after 50 days (~7.1 weeks). Changing the dose or interval starts a new climb toward a new steady state.

Q: How long does Vitamin D3 stay in your system after the last dose?

Roughly 5 half-lives, about 75 days (~10.7 weeks), until about 97% has cleared in the model. Half is gone about 15 days after levels start falling. Real clearance varies from person to person, and a drug can still have effects after levels are low.

Short answer: Vitamin D3 has a half-life of about 15 days (NIH Office of Dietary Supplements 2025) and reaches steady state after about 75 days (~10.7 weeks) of regular dosing. Levels peak about 14 days after a dose by mouth. On a daily schedule the model builds up to about 22.1× a single dose, with a peak-to-trough swing of about 1:1.

What do Vitamin D3 levels look like with daily dosing?

Relative units: 1 on the scale is one full dose. There is no FDA label dose for this use, so the chart shows the shape of the curve, not an amount. Dashed line: 5 half-lives. Change the amount or schedule in the calculator.

When does Vitamin D3 peak after a dose?

Levels peak about 14 days after a dose by mouth.

How long does Vitamin D3 take to reach steady state?

With regular dosing at a fixed amount and interval, levels climb toward steady state by the same fraction every half-life, whatever the dose. At a half-life of about 15 days:

Time from the first dose to each share of steady state, Vitamin D3 (half-life 2.1 weeks).
Share of steady state	Half-lives	Time
50%	1	15 days
75%	2	30 days (~4.3 weeks)
90%	3.3	50 days (~7.1 weeks)
97% (Dose Track's steady-state rule)	5	75 days (~10.7 weeks)

How much do Vitamin D3 levels swing between doses?

The longer the gap between doses compared with the half-life, the bigger the swing from peak to trough and the less the levels build up. These ratios do not depend on the amount.

Steady-state peak:trough and build-up by dosing interval, Vitamin D3, in Dose Track's model.
Interval	Peak : trough	Build-up vs one dose
Daily	1 : 1	22.14×
Every other day	1 : 1	11.33×
Twice weekly	1.01 : 1	6.7×
Weekly	1.03 : 1	3.62×
Every 2 weeks	1.12 : 1	2.1×

Build-up is the accumulation ratio 1 / (1 − e^−k·τ), with k = ln 2 / half-life and τ the interval.

How long does Vitamin D3 stay in your system?

After the last dose, about half is gone every 2.1 weeks. After 5 half-lives, about 75 days (~10.7 weeks), roughly 97% has cleared in the model.

Where do these numbers come from?

Vitamin D has more than one half-life. ODS and a review by Jones (2008) give about 15 days for 25(OH)D, the circulating form; the active hormone lasts hours, and whole-body stores turn over in about 2 months. After a single large dose of D3, 25(OH)D kept rising for about 14 days (Armas 2004; Mentaverri 2019). Dose Track models 25(OH)D, with a 15-day half-life and a peak at 14 days.

The curve uses the half-life, time to peak, route and bioavailability built into the Dose Track app for Vitamin D3, and the same one-compartment model with first-order absorption. These are modeled estimates from published half-lives, drawn with the same one-compartment model as the Dose Track app. Real levels vary from person to person, and only a lab test measures them. This is not medical advice and not a dosing recommendation; dosing decisions belong with you and your prescriber.

Vial sizes and syringe math are in the Vitamin D3 (Cholecalciferol) guide.

When does Vitamin D3 peak and reach steady state?