Reverse GLP-1 Dose Calculator
Convert Syringe Units to mg
Convert U-100 syringe units from medication vials back to milligrams with this free reverse dose calculator. This tool is not for pre-filled pens. Units measure volume, not dosage, which is why a reverse conversion is sometimes needed.
Reverse Dosage Calculator
Medication vials only
How the GLP-1 Reverse Dose Calculator Works
Enter the vial concentration
Enter the concentration in mg/mL or mg/0.5 mL from the vial label. This conversion also applies to retatrutide — RUO (Research use only).
Enter the syringe units injected
Enter the U-100 units to convert into mg. For retatrutide — RUO (Research use only) — enter the scale units for the research calculation.
View the calculated dose in mg
The reverse dose calculator converts syringe units into milliliters, then estimates the actual GLP-1 dose in milligrams (mg) based on the entered concentration.
Understanding Dosage, Concentration and Units
Syringe Units
Syringe units are volume markings on insulin syringes used when injecting GLP-1 medications. On a standard U-100 insulin syringe, 100 units equal 1 mL.
Dosage (mg)
Dosage is the amount of medication, measured in milligrams (mg), rather than syringe units. For retatrutide — RUO (Research use only) — the result represents a research amount in mg.
Concentration (mg/mL)
Concentration describes how many milligrams of medication are contained in each milliliter of liquid. This value is printed on your vial label and is required for accurate units-to-mg conversion for all GLP-1 medications.
Example GLP-1 Dose Calculation
If your vial concentration is 8 mg/mL and you injected 10 units, that equals 0.1 mL.
At this concentration, 0.1 mL contains 0.8 mg of medication.
This means your actual injected dose was 0.8 mg.
Frequently Asked Questions
Common questions about the reverse dose calculator
What is a GLP-1 units-to-mg converter?
A GLP-1 units-to-mg converter, also called a reverse dose calculator, estimates the amount in mg from U-100 units and vial concentration. Calculations involving retatrutide — RUO (Research use only) — are for research purposes.
When would I use a reverse dose calculator?
Use this tool if you recorded an injection from a medication vial in U-100 syringe units and want to calculate the corresponding GLP-1 dosage in mg. Do not use it for pre-filled pens.
Does this work for compounded GLP-1 medications?
The conversion uses the entered concentration and volume. It also supports research calculations for retatrutide — RUO (Research use only). It does not assess a product's quality or recommend its use.
What syringe type does this calculator assume?
The calculator assumes a U-100 insulin syringe, where 100 units equal 1 mL, which is standard for GLP-1 injections.
Is this a dosing recommendation tool?
No. This calculator provides dose estimates only based on entered values. It does not recommend doses or replace medical advice. Retatrutide — RUO (Research use only) — calculations are for research purposes only.
Data Sources
This calculator uses standard pharmaceutical conversion formulas:
- U-100 Syringe Standard — FDA Insulin Delivery Device Guidance (100 units = 1 mL)
- Reverse Calculation Formula — Standard pharmaceutical formula: Dose (mg) = (Units × Concentration mg/mL) ÷ 100
- GLP-1 Medication References — Applicable to tirzepatide, semaglutide, and retatrutide — RUO (Research use only)
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All Tools⚠️ Important Medical Disclaimer
This calculator is for informational purposes only and does not constitute medical advice. Always consult with your healthcare provider before making any changes to your medication dosing.
Dosage calculations should be verified by a healthcare professional. Glapp and its contributors assume no liability for medication dosing errors or adverse events.
Off-Label Use Notice: Split dosing features represent off-label use not approved by the FDA. Discuss with your prescriber before implementing.