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Tirzepatide Dosage Calculator: Tirzepatide Dosing for Weight Loss in Units

This is the most accurate Tirzepatide Dosage Calculator online. Convert your Tirzepatide dose in mg to exact syringe units for compounded vials, Mounjaro, and Zepbound — or reconstitute a lyophilized vial from scratch. Use the Toggle button to change modes. We have also added one-tap dose presets for the full 2.5–15 mg titration.

Choose your calculation mode:


Compounded / pre-mixed: your vial is already mixed and labeled with a concentration (e.g. 20 mg/mL). Enter concentration + dose to get your units.


Syringe Size
What is the total volume of your insulin syringe?



Concentration
Concentration printed on your vial label (mg/mL).




mg/mL


Vial Strength
Total mg of tirzepatide in the vial.






mg


Bacteriostatic Water
How much water are you adding to the vial?






mL


Dose
How much tirzepatide do you want per dose?





Your Result
Set your options to see the result.
Tirzepatide Dose
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Draw To
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Concentration
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Doses Per Vial
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Quick Presets — Tirzepatide Titration Doses
Tap a standard titration dose to load it. Presets set your dose; your current concentration or vial + water stays as-is. Always confirm against your own prescription.

Not medical advice — for education only. This Tirzepatide Dosage Calculator performs a mathematical conversion only and assumes a standard U-100 insulin syringe (100 units = 1 mL). It does not set your dose or confirm any dose is safe, appropriate, or legal for you. Compounded tirzepatide is not FDA-approved. Double-check every number and confirm your dose and vial concentration with your prescriber or pharmacist before drawing or injecting.


How the Tirzepatide Dosage Calculator Works

The Tirzepatide Dosage Calculator above converts a tirzepatide dose in milligrams into the exact number of units to draw on a U-100 insulin syringe. It runs in two modes so it fits every situation. In compounded / pre-mixed mode, you enter the concentration printed on your vial (in mg/mL) and your dose, and the calculator returns your units — the same conversion used for compounded tirzepatide, Mounjaro, and Zepbound. In reconstitution mode, you start from a dry (lyophilized) vial: enter the vial strength in mg and the bacteriostatic water you add, and the Tirzepatide Dosage Calculator works out the concentration for you before converting to units. Most people need the first mode; anyone mixing a research vial from powder needs the second. No other tirzepatide calculator handles both.

The underlying formula is simple and worth understanding, because it is the same math every clinic uses:

Units = (Dose in mg ÷ Concentration in mg/mL) × 100
Based on the U-100 insulin syringe standard, where 100 units = 1 mL.

For example, a 5 mg dose from a 20 mg/mL vial is (5 ÷ 20) × 100 = 25 units. The same 5 mg dose from a 10 mg/mL vial is (5 ÷ 10) × 100 = 50 units. This is why the concentration matters so much: the identical dose can be a completely different number of units depending on how strong your vial is. Copying someone else’s unit count is one of the most common and dangerous mistakes, because their vial may not match yours.

Tirzepatide Dose Chart: mg to Units

This tirzepatide dosage chart shows how many units to draw for each standard dose at the most common compounded concentrations. Find your concentration across the top, your dose down the left side, and read off the units. Any value above 100 units exceeds a 1 mL syringe and needs a larger syringe or a split injection.

Dose 5 mg/mL 10 mg/mL 15 mg/mL 20 mg/mL 34 mg/mL 40 mg/mL
2.5 mg 50 25 17 12.5 7.4 6.3
5 mg 100 50 33 25 14.7 12.5
7.5 mg 150* 75 50 37.5 22 18.8
10 mg 200* 100 67 50 29 25
12.5 mg 250* 125* 83 62.5 37 31.3
15 mg 300* 150* 100 75 44 37.5

*Doses above 100 units exceed a 1 mL syringe and require a larger syringe or a split injection. Values are rounded; use the calculator above for exact figures.

Tirzepatide Titration Schedule (Week by Week)

Tirzepatide is started low and increased slowly to keep gastrointestinal side effects manageable. Everyone begins at 2.5 mg once weekly, and the dose steps up by 2.5 mg roughly every four weeks as tolerated. The standard escalation is the same for compounded tirzepatide and for the brand pens (Mounjaro and Zepbound). Not everyone reaches 15 mg; many people find an effective maintenance dose at 5, 10, or 12.5 mg and stay there.

Weeks Weekly Dose Phase
Weeks 1–4 2.5 mg Starting dose (not a therapeutic dose)
Weeks 5–8 5 mg First maintenance dose
Weeks 9–12 7.5 mg Intermediate step
Weeks 13–16 10 mg Second maintenance dose
Weeks 17–20 12.5 mg Intermediate step
Weeks 21+ 15 mg Maximum approved dose

Providers often hold a dose longer than four weeks if appetite control is already good or if side effects need more time to settle. The titration is a guide, not a race — the goal is the lowest dose that gives you results you can sustain. Restarting after a gap usually means re-titrating from a lower dose rather than resuming where you left off, because tolerance to side effects fades.

Compounded vs. Brand Tirzepatide (Mounjaro & Zepbound)

Brand-name tirzepatide comes as Mounjaro (for type 2 diabetes) and Zepbound (for weight management), both delivered in pre-filled single-dose pens that require no measuring. Compounded tirzepatide is dispensed as a vial and syringe, which is exactly why a Tirzepatide Dosage Calculator is needed: you have to convert your prescribed mg dose into units yourself. The table below summarizes the practical differences.

Brand (Mounjaro / Zepbound) Compounded
FDA approved Yes No
Delivery Pre-filled pen Vial + syringe
Dose calculation Not needed Required (use the calculator)
Dose strengths 2.5–15 mg fixed pens Varies by concentration

What Results Can You Expect?

The pivotal SURMOUNT-1 trial followed 2,539 adults with obesity for 72 weeks. Average weight loss was about 15% of body weight at the 5 mg maintenance dose, roughly 20% at 10 mg, and about 22.5% at the 15 mg maximum dose. These are averages from a supervised trial with diet and activity support — some people lost more than 25%, others closer to 10%. Your own results depend on your starting weight, the dose you can tolerate, and your diet and activity habits. Tirzepatide has a half-life of about five days, which is why it is dosed once weekly and why levels build up gradually over the first several weeks.

How to Inject Compounded Tirzepatide

Brand pens come with their own instructions. For a compounded vial and syringe, the general steps are: wash your hands, check that the liquid is clear and not cloudy, and clean the vial stopper with an alcohol swab. Draw your calculated number of units into a U-100 insulin syringe, tap out air bubbles, and clean the injection site. Inject subcutaneously into the abdomen (at least two inches from the navel), the front of the thigh, or the back of the upper arm, rotating sites each week to avoid lumpy skin. Store compounded vials refrigerated at 2–8°C, use within the timeframe your pharmacy specifies (commonly 28–30 days after first puncture), and never freeze. Always follow the specific instructions from your prescriber or pharmacy over any general guide.

Common Mistakes to Avoid

Three errors cause most dosing problems. First, confusing mg/mL with mg/0.5mL: if your vial says “5 mg/0.5 mL,” that is actually 10 mg/mL — double the number before you enter it. Second, using the wrong syringe: this calculator assumes a U-100 insulin syringe, and a U-40 syringe has entirely different markings that will give the wrong dose. Third, reusing someone else’s unit count: units only translate to a dose if the concentration matches, so always recalculate when you get a new vial, especially after switching pharmacies. When in doubt, confirm the concentration on your label and re-run the Tirzepatide Dosage Calculator.

Tirzepatide Dosage Calculator: Frequently Asked Questions

How many units is 2.5 mg of tirzepatide?
It depends entirely on your vial concentration. On a U-100 syringe, 2.5 mg is 50 units from a 5 mg/mL vial, 25 units from a 10 mg/mL vial, 12.5 units from a 20 mg/mL vial, and about 7 units from a 34 mg/mL vial. The formula is (2.5 ÷ concentration) × 100. Enter your exact concentration in the calculator above for your specific number.

How many units is 5 mg of tirzepatide?
A 5 mg dose is 25 units from a 20 mg/mL vial, about 29 units from a 17 mg/mL vial, 50 units from a 10 mg/mL vial, and a full 100 units from a 5 mg/mL vial. Because 5 mg from a 5 mg/mL vial fills an entire 1 mL syringe, higher concentrations are common at this dose to keep the draw small.

How many units is 7.5 mg of tirzepatide?
A 7.5 mg dose is 37.5 units from a 20 mg/mL vial, 50 units from a 15 mg/mL vial, and 75 units from a 10 mg/mL vial. From a 5 mg/mL vial it would need 150 units, which exceeds a 1 mL syringe and requires a larger syringe or a split injection.

How many mg is 40 units of tirzepatide?
Reverse the formula: mg = (units ÷ 100) × concentration. So 40 units is 8 mg from a 20 mg/mL vial, 4 mg from a 10 mg/mL vial, and 2 mg from a 5 mg/mL vial. Without knowing your concentration, 40 units has no fixed dose — units are a volume measure, not a dose.

How many mg is 50 units of tirzepatide?
50 units is exactly half of a 1 mL U-100 syringe, or 0.5 mL. That equals 10 mg from a 20 mg/mL vial, 5 mg from a 10 mg/mL vial, and 2.5 mg from a 5 mg/mL vial. Check your vial’s concentration and use the reverse lookup or the calculator to confirm.

What concentrations do compounded tirzepatide vials come in?
Compounded tirzepatide is commonly dispensed at 5, 10, 20, or 34 mg/mL, though concentrations vary by pharmacy and some go higher. Tirzepatide is often more concentrated than other peptides because the doses are relatively large. Some labels use a mg/0.5 mL format — “10 mg/0.5 mL” is the same as 20 mg/mL. Always verify the exact concentration printed on your vial before calculating.

What is the difference between mg/mL and mg/0.5 mL?
Both describe concentration, just over a different volume. “mg/mL” is milligrams per full milliliter; “mg/0.5 mL” is milligrams per half milliliter. To convert mg/0.5 mL to mg/mL, multiply by two: 5 mg/0.5 mL = 10 mg/mL, and 10 mg/0.5 mL = 20 mg/mL. Always convert to mg/mL before entering a value in the calculator, or you will draw half the units you need.

Why does my dose need more than 100 units?
A standard U-100 insulin syringe holds 100 units (1 mL). If your dose needs more than that, your vial is too dilute for that dose — for example, 7.5 mg from a 5 mg/mL vial works out to 150 units. The fix is to use a higher-concentration vial, draw into a larger syringe, or split the dose into two injections. Confirm the right approach with your pharmacy.

What is the starting dose of tirzepatide?
The starting dose of tirzepatide is 2.5 mg once weekly for the first four weeks, for all brand names and compounded forms. The 2.5 mg dose is an introductory dose meant to let your body adjust and reduce side effects — it is not considered a full therapeutic dose. After four weeks, the dose typically increases to 5 mg, then continues stepping up every four weeks as tolerated.

Is it safe to stay on 2.5 mg tirzepatide for weight loss?
The 2.5 mg dose is designed as a four-week starting dose rather than a long-term maintenance dose, and clinical trials showed greater average weight loss at higher doses. That said, some people do respond at 2.5 mg, and a few stay on lower doses because of side effects or personal preference. Whether staying at 2.5 mg makes sense for you is a decision for your prescriber, who can weigh your results against the expected benefit of titrating up.

Is tirzepatide the same as Ozempic?
No. Ozempic is a brand of semaglutide, a GLP-1 receptor agonist. Tirzepatide (sold as Mounjaro and Zepbound) is a dual GIP and GLP-1 receptor agonist, meaning it activates two hormone pathways rather than one. Both are once-weekly injections used for blood sugar control and weight management, but they are different molecules, and their doses and unit conversions are not interchangeable.

What does the drug tirzepatide do?
Tirzepatide mimics two gut hormones, GIP and GLP-1, that regulate blood sugar and appetite. It prompts the pancreas to release insulin when blood sugar is high, slows how quickly the stomach empties, and reduces appetite and food cravings. It is FDA-approved to treat type 2 diabetes (as Mounjaro) and for chronic weight management (as Zepbound), used alongside diet and exercise.

What are the negative side effects of tirzepatide?
The most common side effects are gastrointestinal: nausea, diarrhea, constipation, vomiting, and reduced appetite, usually worst in the first weeks and after each dose increase. Fatigue and injection-site reactions also occur. Less common but serious risks include pancreatitis, gallbladder problems, and low blood sugar (especially when combined with insulin or sulfonylureas). Seek care for severe abdominal pain, signs of an allergic reaction, or persistent vomiting. Discuss your full risk profile with your provider.

Who cannot take tirzepatide?
Tirzepatide is not recommended for people with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2, or anyone who has had a serious allergic reaction to it. It should not be used during pregnancy or breastfeeding. People with a history of pancreatitis, severe gastrointestinal disease, or diabetic retinopathy need careful evaluation. Because it can reduce the absorption of oral medications, including birth control pills, tell your provider everything you take. Only a clinician can determine whether it is appropriate for you.

Is tirzepatide safer than Ozempic?
Neither is categorically “safer” — they share a similar side-effect profile dominated by gastrointestinal symptoms, and both carry the same class warnings. In head-to-head research, tirzepatide produced greater average weight loss than semaglutide, but greater potency can also mean more pronounced side effects for some people. The better choice depends on your health history, goals, tolerance, and cost. That comparison is best made with your prescriber.

How long does it take to lose 20 pounds on tirzepatide?
It varies widely, but for someone starting around 200 lbs, 20 lbs is roughly 10% of body weight — a level many trial participants reached somewhere between two and five months, often as they titrated up to the 10 mg range. Early weeks at the 2.5 mg starting dose typically produce more modest loss. Your pace depends on starting weight, dose tolerated, diet, and activity. These are averages, not guarantees.

How much weight can I lose in 2 months on tirzepatide?
In the first two months you are usually still titrating — four weeks at 2.5 mg, then four at 5 mg — so weight loss is typically in the range of a few pounds up to around 5% of body weight for many people, though individual results vary. The larger losses reported in trials accumulated over many months at higher maintenance doses. Rapid early loss is not the goal; steady, tolerable progress is.

What syringe should I use for tirzepatide injections?
Compounded tirzepatide is drawn with a standard U-100 insulin syringe (100 units = 1 mL). This calculator is built for U-100 syringes. Do not use a U-40 syringe — its markings are on a different scale and will give the wrong dose. For small doses, a 0.3 mL (30-unit) syringe makes the markings easier to read; for larger draws you may need a 0.5 mL or 1 mL syringe.

How should I store compounded tirzepatide?
Keep compounded tirzepatide vials refrigerated at 2–8°C (36–46°F) and use within the window your pharmacy specifies, commonly 28–30 days after the first puncture. Never freeze it, and protect it from light. Brand pens can generally be kept at room temperature for a limited number of days once in use — check the specific product instructions. Discard any vial whose liquid is cloudy or discolored.

Sources & References

1. Calculation formula: Units = (Dose mg ÷ Concentration mg/mL) × 100, based on the U-100 insulin syringe standard (100 units = 1 mL).

2. FDA Zepbound Prescribing Information

3. FDA Mounjaro Prescribing Information

4. Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). N Engl J Med. 2022;387(3):205-216

5. Mayo Clinic: Tirzepatide (subcutaneous route)

Resources

Explore every free tool and reference on Bio Peptide Calculator. Start with the main Peptide Calculator: Reconstitution and Dosage Calculator, browse the hubs, or jump straight to a compound-specific calculator or dosing chart.

Resources & Further Reading

Authoritative sources on tirzepatide dosing, efficacy, and safety. Always follow the guidance of your prescriber and the official prescribing information for your specific product.

Official FDA Prescribing Information

Manufacturer (Eli Lilly) Pages

Peer-Reviewed Studies (PubMed / NEJM)

General Medical References

Note: These resources are for education only. Compounded tirzepatide is not FDA-approved. Always confirm your dose, concentration, and injection technique with your prescriber or pharmacist before use.