Short answer
At the most common dose of 500 IU a week, one 10,000 IU order lasts about 19–20 weeks.
Each order is 10,000 IU. You mix it with the 10 mL of solvent the pharmacy sends, which gives 1,000 IU per mL.
How long it lasts depends on your prescribed dose:
- 500 IU a week (the most common): about 19–20 weeks
- 750 IU a week: about 12–13 weeks
- 1,000 IU a week: about 9–10 weeks
- 1,500 IU a week: about 5½–6½ weeks
Follow the storage directions on your pharmacy label, and don't use it past the discard date on the label.