Vitamin Days Supply Calculator
Turn pill count, daily dose, and buffer into days supply and reorder day.
What it does
Supplement bottles run out silently when daily counts drift. One hundred twenty pills at 2 a day last 60 days, so a 7 day buffer puts reorder on day 53, not the empty morning.
The tool above takes pill count, daily dose, and buffer days. It returns days supply, weeks supply, and reorder day, so cabinets restock before gaps.
This math tracks quantity only. It does not set doses, which depend on age, diet, sun, and clinician guidance, nor does it judge brand quality.
Supplement guidance frames the same split: daily needs vary by life stage with upper limits beside them, and label databases track what each bottle holds. Count math here converts bottles to calendars.
Write the reorder day on the cap. Bottles without dates always surprise at the worst moment.
How to use
- Count pills in the full bottle.
- Enter pills taken daily.
- Enter buffer days for shipping.
- Read days supply first for the run length.
- Read weeks for the calendar feel.
- Read reorder day and set a reminder.
Formula
- pills
- Tablets in the full bottle.
- daily
- Tablets taken each day.
- buffer
- Days early to reorder for shipping.
Buffer cannot top planning here since reorder floors at zero. Split doses across two bottles need one run per bottle.
Worked example
Example: 120 pills, 2 daily, 7 day buffer
Pills 120, daily 2, buffer 7 days.
- Days: 120 / 2 = 60 days.
- Weeks: 60 / 7 = 8.6 wks.
- Reorder: 60 - 7 = day 53.
- Tool shows 60 days, 8.6 wks, reorder day 53.
- Reminder: order in week 7 to land before day 60.
Reference table
| Daily | Days supply | Reorder day |
|---|---|---|
| 1 | 120 days | day 113 |
| 2 | 60 days | day 53 |
| 4 | 30 days | day 23 |
Limits
- Counts only. Doses need clinician and label guidance.
- Ignores split bottles with different strengths.
- Ignores travel and missed dose drift.
- Expiry before empty still discards the rest.
Common mistakes
- Forgetting the buffer until the bottle empties.
- Changing daily dose without rerunning supply.
- Mixing two strengths in one count.
- Reading weeks as exact calendar months.
- Reordering on empty day with shipping lag.
Try it yourself
Quick checks. Answers sit tucked under each question.
30 pills, 1 daily, no buffer?
30 days, 4.3 wks, reorder day 30.
90 pills, 3 daily, 5 day buffer?
30 days, 4.3 wks, reorder day 25.
200 pills, 4 daily, 10 day buffer?
50 days, 7.1 wks, reorder day 40.
Questions
How long will my vitamins last?
Pills divided by daily count. 120 at 2 a day is 60 days.
When should I reorder?
Days supply minus buffer. 60 days with 7 buffer reorders day 53.
How many weeks is that?
Days divided by 7. 60 days is about 8.6 weeks.
Does this set my dose?
No. Doses follow age, diet, and clinician guidance on labels.
What if I miss doses?
Supply stretches. Rerun with remaining pills for the true reorder day.
Can I get too much?
Yes above upper limits. More pills per day is not always better.