The standard peptide calculator works forward: dose → syringe units. This tool works backwards - converting syringe units to mg/mcg, finding the BAC water volume for a target concentration, or verifying a draw matches your protocol. For multi-peptide vials, use the blend calculator.
I drew X units - how much peptide is that?
Enter vial size, BAC water, and units drawn to see results.
The standard peptide calculator answers: "I want 250 mcg - how many units do I draw?" The reverse calculator answers 3 different questions by rearranging the same formula.
The core relationship is: Dose = Units × (Vial Size ÷ BAC Water ÷ 100)
Mode 1 (Units → Dose): You know the units you drew, the vial size, and the BAC water. The calculator multiplies units by mcg-per-unit to give you the dose.
Mode 2 (Target Concentration → BAC Water): You know the vial size and the concentration you want. The calculator divides the vial size by the target concentration to give you the BAC water volume.
Mode 3 (Dose Verification): You know everything. The calculator computes the actual dose from the units drawn and compares it to your target, flagging any mismatch.
You drew 35 units from a semaglutide vial reconstituted with 2 mL BAC water. Was that 0.875 mg or 1.75 mg? The answer depends entirely on the vial size - mixing up a 5 mg vial (2.5 mg/mL) with a 10 mg vial (5 mg/mL) at the same BAC water volume doubles the dose. Mode 1 resolves this in seconds.
You want every dose tier of tirzepatide to land on round syringe units. Mode 2 lets you enter your vial size and target concentration, then shows the exact BAC water and a quick-reference table of units for every common dose.
A protocol says "draw 25 units from a 10 mg/mL retatrutide solution." Mode 3 confirms that equals 2.5 mg - and flags it if the math doesn't match.
| Concentration | mcg per Unit | mg per 10 Units | mg per 50 Units | mg per 100 Units |
|---|---|---|---|---|
| 1 mg/mL | 10 mcg | 0.1 mg | 0.5 mg | 1.0 mg |
| 2.5 mg/mL | 25 mcg | 0.25 mg | 1.25 mg | 2.5 mg |
| 5 mg/mL | 50 mcg | 0.5 mg | 2.5 mg | 5.0 mg |
| 10 mg/mL | 100 mcg | 1.0 mg | 5.0 mg | 10.0 mg |
| 15 mg/mL | 150 mcg | 1.5 mg | 7.5 mg | 15.0 mg |
| 20 mg/mL | 200 mcg | 2.0 mg | 10.0 mg | 20.0 mg |
Critical: These numbers change entirely if your actual concentration is different from what you assumed. Always verify concentration before referencing any conversion table. For a detailed walkthrough of the unit conversion math, see the how to calculate peptide doses guide.
| Tool | What It Does |
|---|---|
| Peptide Reconstitution Calculator | Forward calculator: dose → syringe units (the standard tool) |
| Tirzepatide Calculator | Tirzepatide-specific with titration schedule |
| Semaglutide Calculator | Semaglutide-specific with dose escalation schedule |
| Blend Calculator | Multi-peptide vial dosing |
| BAC Water Calculator | Recommended BAC water volumes by peptide and dose |
| Cost-per-Dose Calculator | Compare costs across vendors and vial sizes |
Divide the units drawn by 100 to get millilitres. Multiply by your concentration in mg/mL. Example: 20 units from a 2.5 mg/mL solution = 0.2 mL × 2.5 = 0.5 mg. The formula is: Dose (mg) = (Units ÷ 100) × Concentration (mg/mL). Mode 1 of this calculator performs the conversion automatically.
Divide the vial size (in mg) by the concentration you want (in mg/mL). Example: 10 mg vial ÷ 5 mg/mL target = 2 mL BAC water. Mode 2 calculates this and shows a quick-reference table of syringe units for common doses at the resulting concentration.
Small measurement imprecision is normal with insulin syringes - particularly at low draw volumes (under 10 units). Mode 3 categorises the difference: within 5% is an accurate draw, 5-15% off is acceptable but imprecise, and over 15% off indicates a likely error in concentration, syringe type, or calculation.
The dose calculation is identical regardless of syringe size - all U-100 insulin syringes use the same scale (100 units = 1 mL). A 30-unit syringe provides finer graduation marks, improving accuracy for small draws. Choose based on your typical draw volume, not the math.
No. Pre-filled pens deliver a fixed dose per click - no syringe measurement or concentration calculation is involved. This tool is for compounded lyophilised peptides reconstituted with BAC water and drawn with an insulin syringe.
You cannot determine concentration without knowing both the vial size and the BAC water volume. If the BAC water volume is unknown, the only way to verify your dose is to reconstitute a new vial with a measured amount. Label every vial with the reconstitution date, BAC water volume, and calculated concentration immediately after mixing. For reconstitution best practices, see reconstituting peptides step by step.
This calculator is for educational and research purposes only and does not constitute medical advice. Peptides discussed may be investigational compounds not approved by the FDA for human use. Always consult a qualified healthcare provider before using any peptide or research compound. Peptigrity is an independent review platform and does not sell, endorse, or recommend specific products or vendors.