PepKeep › Dose calculator
Dose calculator
Enter the numbers you know, and it works out the one you don't, for a U-100 insulin syringe.
Track it all. Just tell Siri.
This calculator is one small part of PepKeep. Keep your whole routine in one place, and run it by voice, hands-free.
- DosesThe exact units to draw, every time
- Logging“Siri, PepKeep, log my shot”
- Weigh-insYour weight next to your doses, with a chart
- RemindersA nudge at every dose time
- VialsWhat's left, and when to reorder
- CostsThe real price of every shot
Or just ask Siri.
PepKeep remembers your vial and water, so you never redo this. Say “Siri, PepKeep, how many units do I draw?” and hear the answer. It logs the shot, logs your weight and tells you when to reorder, without opening the app.
Tap a question to hear the answer:
Talk to PepKeepR right here: ask any dose math out loud or type it. iPhone users can also add the free PepKeep Siri shortcut. PepKeep never suggests a dose; it does the math on your own plan.
How the units math works
A U-100 insulin syringe holds 100 units in 1 mL, so each unit is 0.01 mL. Once you know how much medication is in each mL, the units follow:
volume per dose (mL) = dose (mg) ÷ concentration
units to draw = volume per dose × 100
Example: 5 mg mixed with 2 mL of water is 2.5 mg/mL. A 250 mcg (0.25 mg) dose is 0.1 mL, which is 10 units. The vial holds 20 doses.
Picking how much water to add
More water makes each dose a bigger, easier-to-read draw; less water keeps small syringes usable. A common goal is a dose that lands on a whole tick between about 5 and 50 units. Change the water above and watch where the dose lands. The water doesn't change how many doses the vial holds, only how many units each one is.
Questions
How many units do I draw on an insulin syringe?
Divide the amount in the vial by the water you added to get mg per mL. Divide your dose by that to get mL, then multiply by 100 for units on a U-100 syringe. 5 mg in 2 mL is 2.5 mg/mL; a 0.25 mg dose is 0.1 mL, or 10 units.
How much bacteriostatic water should I add?
Any amount that makes your dose an easy, readable draw on your syringe. More water means more units per dose. The amount of water doesn't change how many doses the vial holds.
What's the difference between mg and mcg?
1 mg = 1,000 mcg. Mixing them up is the most common dosing mistake, so the calculator lets you pick the unit for the vial and the dose separately.
Do I need to recalculate when my dose changes?
Yes. Every dose change changes the units. PepKeep keeps step-up plans on schedule and shows the units to draw at each reminder.
Is this calculator medical advice?
No. It does the arithmetic on the numbers you enter. It doesn't recommend compounds or doses, and you should double-check every draw.
Let PepKeep do this math for you, every day.
Reminders with the exact units to draw, vials that count down, and your real cost per shot, month and year. iPhone, Android and desktop.
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Sources
This page only does the math. The FDA has warned that confusion between milliliters, milligrams and units can lead to dosing errors, so check your syringe markings too.