PeptideWise

Vial Days Remaining Calculator

Estimates how many administrations a reconstituted peptide vial provides, the calendar duration of those doses, and the approximate date of the last full administration.

Vial mass
Dose per administration
Administration frequency
First administration date

Estimated vial duration

Administrations per vial
20 doses
Calendar duration
19 days

1 day between administrations

Estimated last full administration
June 2, 2026

This estimate assumes consistent dosing and ignores draw waste, evaporation, and reconstituted-vial stability windows. Always verify with your prescriber and the peptide compounding label.

How the calculation works

Total administrations is the floor of vial mass / dose per administration. Calendar duration is (administrations - 1) × days between doses, because the first dose is given on day 0. For a 5 mg vial dosed at 250 mcg daily, the math isfloor(5000 / 250) = 20 doses across(20 - 1) × 1 = 19 days.

Frequency spacing: daily = 1 day, every other day = 2 days, twice weekly = 3.5 days, weekly = 7 days. A custom interval option is available for non-standard schedules.

Limitations

  • Estimates assume consistent dose and frequency for the entire vial.
  • Does not account for reconstituted-vial stability (typically 4-8 weeks refrigerated).
  • Does not account for syringe dead volume or unrecoverable vial residual.
  • Calendar arithmetic uses UTC dates and may show a one-day shift in your local timezone.
  • For informational purposes only. Not a substitute for professional medical advice.

Sources

  1. USP <797> Pharmaceutical Compounding — Sterile Preparations. United States Pharmacopeia.
  2. Stability of Reconstituted Lyophilized Peptides. Journal of Pharmaceutical Sciences.

Frequently Asked Questions

How does the calculator estimate the runout date?
The calculator divides total vial mass by dose per administration to get the number of full doses, then multiplies (doses minus one) by days between administrations to get the calendar span from first to last dose. Partial doses are not counted — only complete administrations.
What does "twice weekly" mean for spacing?
Twice-weekly schedules are typically Monday and Thursday or Tuesday and Friday — averaging 3.5 days between doses. The calculator uses 3.5 days as the spacing constant. Real-world schedules may be slightly asymmetric (3 days and 4 days).
Why does it ignore reconstituted-vial stability windows?
Reconstituted peptide stability varies by compound and storage conditions — typically 4-8 weeks refrigerated for peptides in bacteriostatic water. The calendar duration the calculator produces may exceed the practical shelf-life of the reconstituted solution. Check the peptide compounding label and consult your prescriber.
What if my schedule changes during the vial?
The calculator assumes one consistent dose and frequency for the whole vial. If you titrate up mid-vial, recalculate after the titration with the new dose. Many peptides have variable schedules in practice; treat this as a planning estimate.
Why are partial doses excluded?
A vial typically has small unrecoverable dead volume in the bottom plus syringe and needle dead volume. The calculator floors to whole doses (e.g. 5 mg vial / 300 mcg dose = 16 doses, not 16.67) because the last fractional draw is rarely a full clinical dose.