How many units is 2.5mg of tirzepatide?

It depends on your vial concentration. At 10mg/mL, 2.5mg equals 25 units. At 5mg/mL, it's 50 units.

Can I take tirzepatide twice a week?

Tirzepatide is designed for once-weekly dosing. Taking it more frequently is not recommended.

What happens if I miss a dose?

Take it within 4 days of your scheduled dose. If more than 4 days passed, skip it and take your next dose on schedule.

How should I store tirzepatide?

Refrigerate at 2-8°C (36-46°F). Compounded vials should be used within 28-30 days of first puncture.

Tirzepatide Dosage Calculator

Q: What is the starting dose of tirzepatide?

The starting dose is 2.5mg once weekly for 4 weeks. After that, your dose increases by 2.5mg every 4 weeks.

Convert your dose (mg) + vial concentration (mg/mL or mg/0.5mL) into syringe units. Works for compounded tirzepatide, Mounjaro, and Zepbound. Assumes U-100 insulin syringe.

What this calculator does

This free tirzepatide dosage calculator converts a prescribed dose in milligrams (mg) and a vial concentration (mg/mL or mg/0.5mL) into the number of units to draw in a U-100 insulin syringe. It supports compounded tirzepatide vials (5-50 mg/mL), brand-name Mounjaro and Zepbound pens (2.5-15 mg), reverse lookup (units to mg), vial-to-vial transitions, and split-dose schedules. Built by Lina, the companion app for GLP-1 users.

Vial Concentration

Target Dose (mg)

Calculator Assumptions

• Uses U-100 insulin syringe standard (100 units = 1mL)
• Formula: Units = (Dose mg ÷ Concentration mg/mL) × 100
• Supports both mg/mL and mg/0.5mL label formats
• Sources: FDA Mounjaro & Zepbound prescribing information

Common Mistakes to Avoid

Confusing mg/mL with mg/0.5mL: If your vial says "5mg/0.5mL", that's actually 10mg/mL. Flip the toggle in the calculator.
Wrong syringe type: This calculator assumes U-100 syringes. U-40 syringes have completely different markings — using the wrong one means wrong dose.
Copying someone else's units: Your concentration might be different. "50 units" only works if you have the same vial concentration.
Not checking after pharmacy switch: Different compounding pharmacies use different concentrations. Always recheck when you get a new vial.

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Medical Disclaimer

This calculator is for informational purposes only and does NOT replace medical advice. Always verify your dose with your healthcare provider before injecting. Compounded tirzepatide is not FDA-approved.

Created by Lina · Formula verified against FDA prescribing info

Updated: Jan 2026

Understanding Tirzepatide Dosing: mg, mL, and Units

With compounded tirzepatide, you need to calculate your own dose — the vial + syringe combo doesn't do it for you like brand pens do. You have three numbers to understand: your dose (mg), your vial's concentration (mg/mL), and the units you'll draw on your syringe. Get any of these wrong and you'll inject the wrong amount.

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Your Dose (measured in mg)

This is the amount of tirzepatide your provider has prescribed for you to take each week. Everyone starts at 2.5mg for the first four weeks, then gradually increases. The standard doses are 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg, and 15mg. Your dose will be written as something like "5mg weekly" on your prescription.

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Vial Concentration (mg/mL)

This tells you how strong the medication in your vial is — how many milligrams of tirzepatide are dissolved in each milliliter of liquid. You'll find this number on your vial's label. Common concentrations include 5mg/mL, 10mg/mL, 20mg/mL, and higher. A higher concentration means you need to inject less liquid to get the same dose.

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Volume (measured in mL)

This is the actual amount of liquid you'll inject. It's calculated by dividing your dose by your concentration. For example, if you need 5mg and your vial is 10mg/mL, you'd inject 0.5mL (5 ÷ 10 = 0.5). The calculator figures this out for you automatically.

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Units (what you see on the syringe)

Insulin syringes are marked in "units" rather than milliliters. On a standard U-100 insulin syringe, 100 units equals exactly 1mL. So if you need to inject 0.5mL, you'd draw up to the 50-unit mark. This is the number the calculator gives you — the unit marking to look for on your syringe.

The Formula Behind the Calculator

If you're curious about the math, here's how it works: Units = (Your Dose in mg ÷ Concentration in mg/mL) × 100. For example, if you're taking a 5mg dose from a 10mg/mL vial: (5 ÷ 10) × 100 = 50 units. But don't worry about memorizing this — that's exactly what the calculator above does for you.

Just enter your numbers and let us handle the math. Double-check your result with your healthcare provider before your first injection.

What is the starting dose of tirzepatide?

The starting dose of tirzepatide is 2.5mg once weekly for 4 weeks. This applies to all brand names (Mounjaro, Zepbound) and compounded tirzepatide. After the initial 4 weeks, your dose increases by 2.5mg every 4 weeks until you reach your maintenance dose — typically 5mg, 10mg, or 15mg depending on how you respond and what you can tolerate.

What Results Can You Expect?

The SURMOUNT-1 trial followed 2,539 adults for 72 weeks. Average weight loss ranged from 15% at the 5mg dose to 22.5% at 15mg. Your results will vary based on your starting weight, the dose you can tolerate, and your diet/exercise habits. Trial participants had dietitian support and regular check-ins — most real-world users don't.

15%

At 5mg maintenance dose

Average body weight reduction after 72 weeks. For someone starting at 200 lbs, that's about 30 lbs lost.

20%

At 10mg maintenance dose

Average body weight reduction after 72 weeks. For someone starting at 200 lbs, that's about 40 lbs lost.

22.5%

At 15mg maximum dose

Average body weight reduction after 72 weeks. For someone starting at 200 lbs, that's about 45 lbs lost.

Important Context About These Numbers

These are averages from clinical trials, which means some people lost more and some lost less. Several factors influence your personal results: your starting weight, how well you tolerate the medication (and therefore which dose you can reach), your diet and exercise habits, and your individual metabolism. Some people in the trials lost over 25% of their body weight, while others lost closer to 10%. Both outcomes can be meaningful improvements for your health.

Your Weight Loss Timeline: What to Realistically Expect

Weeks 1-4

The first month is your adjustment period at the 2.5mg starting dose. Many people notice their appetite decreasing and what some call "food noise" — that constant thinking about food — starting to quiet down. Weight loss during this phase is typically modest, maybe 2-5 pounds. GI side effects like nausea are most common during this time but usually manageable.

Months 2-3

As you move to 5mg and potentially 7.5mg, weight loss becomes more noticeable. You might find that clothes fit differently, that you're satisfied with smaller portions, and that cravings are significantly reduced. Most people lose 5-10% of their starting weight by the end of month three. Side effects typically stabilize as your body adjusts.

Months 4-6

This is often when the most dramatic changes happen. You're likely at a higher dose now (10mg or above for many people), and weight loss is in full swing. Many people have found their "sweet spot" — the dose where they're seeing good results with tolerable side effects. You might lose another 10% of your body weight during this period.

Month 6+

Weight loss continues but typically at a slower pace. This is completely normal — your body is approaching a new set point. The focus shifts to maintaining your progress, preserving muscle mass through adequate protein intake and exercise, and establishing habits that will serve you long-term. Some people continue losing weight for 12-18 months on treatment.

Tirzepatide Titration Schedule by Week

Dosing follows a gradual increase to keep side effects manageable. Don't rush through the titration.

2.5

2.5mg

Week 1-4

5mg

Week 5-8

7.5

7.5mg

Week 9-12

10mg

Week 13-16

12.5

12.5mg

Week 17-20

15mg

Week 21+

Week	Dose	Phase	What to Expect
1-4	2.5mg	Starting	Dose adjustment period. Mild nausea is common. Appetite reduction begins.
5-8	5mg	First maintenance	Side effects typically stabilize. Noticeable appetite suppression.
9-12	7.5mg	Intermediate	Optional step. Some providers skip to 10mg if 5mg is well-tolerated.
13-16	10mg	Second maintenance	Strong appetite suppression. Significant weight loss expected.
17-20	12.5mg	Intermediate	Approach with caution. Only increase if needed.
21+	15mg	Maximum	Highest approved dose. Not everyone needs to reach this level.

How to Inject Tirzepatide

Step-by-step instructions for compounded vial injections. Brand pens have their own instructions included.

1Choose Your Injection Site

Rotate between these areas each week:

✓ Abdomen (at least 2 inches from belly button)
✓ Front of thighs (middle outer area)
✓ Back of upper arms (if someone can help)

Rotate sites to prevent lipohypertrophy (lumpy skin). Don't inject in the same spot two weeks in a row.

2Prepare Your Injection

1. Wash hands thoroughly with soap and water
2. Check the vial — liquid should be clear, not cloudy
3. Clean the vial stopper with an alcohol swab
4. Draw air into syringe equal to your dose volume
5. Inject air into vial, then draw your medication
6. Remove air bubbles by tapping and pushing out

3Perform the Injection

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Clean the site

Use alcohol swab, let dry

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Pinch the skin

Gently lift a fold of skin

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Insert needle

At 45-90° angle, push plunger slowly

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Wait 10 seconds

Then remove needle straight out

Storage Requirements

Compounded Vials

• Refrigerate at 2-8°C (36-46°F)
• Use within 28-30 days of first puncture
• Never freeze

Brand Pens

• Refrigerate until first use
• Can be kept at room temp (up to 30°C/86°F) for 21 days
• Never freeze

Managing Tirzepatide Side Effects

Nausea, constipation, fatigue — if you're on tirzepatide, you've probably experienced at least one. About 20-30% of users report nausea in clinical trials, and it's most common during weeks 1-4 and after each dose increase. Most side effects ease up within 2-3 weeks as your body adjusts. Below are specific strategies that actually help, based on what works.

🤬 Nausea

Nausea is the most commonly reported side effect, affecting around 20-30% of users. It happens because tirzepatide slows down how quickly your stomach empties, which can leave you feeling queasy — especially if you eat too much or too quickly.

The key is to eat smaller portions more frequently throughout the day rather than three big meals. Think of it as grazing. Avoid foods that are high in fat or grease, as these take longer to digest and can make nausea worse. Many people find that ginger helps — whether it's ginger tea, ginger chews, or even ginger ale (the real stuff, not artificially flavored).

Another tip: stay upright for at least 30 minutes after eating. Lying down right after a meal puts pressure on your stomach and can trigger that uncomfortable feeling. If nausea is really bothering you, talk to your provider about anti-nausea medications like ondansetron, which can help bridge the adjustment period.

💪 Constipation

Because tirzepatide slows down your entire digestive system, things can get a bit... backed up. About 15-20% of users experience constipation, and it can be uncomfortable if you don't address it early.

Hydration is your best friend here. Aim for at least 8-10 glasses of water per day — more if you're active or it's hot outside. Since you're eating less food overall, you're also getting less fiber naturally, so consider adding a fiber supplement like psyllium husk or eating fiber-rich foods like vegetables, berries, and chia seeds.

Movement helps too. Even a daily 20-minute walk can get things moving. If you've been constipated for more than a few days, over-the-counter stool softeners like docusate sodium are generally safe to use. For persistent issues, your provider might recommend magnesium citrate or other gentle laxatives.

😓 Fatigue & Low Energy

Feeling tired during the first few weeks is common and usually has a simple explanation: you're eating fewer calories. Your body is adjusting to a new energy intake, and that transition can leave you feeling drained.

The solution isn't to eat more, but to eat smarter. Protein is essential — aim for at least 60-100 grams per day to preserve muscle mass and maintain energy levels. Many tirzepatide users find that focusing on protein at every meal makes a noticeable difference in how they feel.

Also check that you're staying hydrated and getting enough sleep. Interestingly, light exercise can actually boost your energy levels even when you feel tired. If fatigue is severe or accompanied by shakiness, sweating, or confusion, check your blood sugar — these could be signs of hypoglycemia, especially if you're also taking diabetes medications.

Other Side Effects You Might Notice

Diarrhea

Some people experience loose stools, especially after eating fatty foods. This usually improves with time. Stay hydrated if this happens, and consider temporarily reducing fat intake until your system adjusts.

Injection Site Reactions

You might notice redness, itching, or a small bump where you inject. This is usually mild and goes away on its own. Rotating injection sites helps prevent this from becoming a recurring issue.

Hair Thinning

Some users report temporary hair shedding, which is related to rapid weight loss rather than the medication itself. Ensuring adequate protein intake can help minimize this. Hair typically regrows once weight stabilizes.

Decreased Appetite

This is actually how the medication works, but sometimes it can feel extreme. Even if you're not hungry, try to eat something — especially protein — to maintain your nutrition and energy levels.

When to Get Medical Help Right Away

While most side effects are manageable at home, some symptoms require immediate medical attention. Don't wait to contact your healthcare provider or seek emergency care if you experience any of the following:

Severe abdominal pain: Especially pain that radiates to your back, doesn't go away, or is accompanied by vomiting. This could indicate pancreatitis, a rare but serious inflammation of the pancreas.

Signs of an allergic reaction: Swelling of your face, lips, tongue, or throat, difficulty breathing, severe rash, or rapid heartbeat require emergency care.

Severe hypoglycemia: If you experience confusion, shakiness, sweating, rapid heartbeat, or lose consciousness, you need immediate help — especially if you take insulin or other diabetes medications.

Persistent vomiting or diarrhea: If you can't keep fluids down for more than 24 hours or have severe diarrhea, you risk dehydration and need medical evaluation.

Important Safety Information

Who Should Talk to Their Doctor First

Tirzepatide is generally well-tolerated, but it's not right for everyone. Before starting treatment, have an honest conversation with your healthcare provider if any of these situations apply to you.

If you've had a serious allergic reaction to tirzepatide or any of its ingredients in the past, you shouldn't use it again. Symptoms of an allergic reaction can include swelling of your face, lips, tongue, or throat, difficulty breathing, or a severe rash.

Women who are pregnant, planning to become pregnant, or breastfeeding should not use tirzepatide. The medication can affect fetal development, and it's recommended to stop tirzepatide at least 2 months before trying to conceive.

Medications That May Interact

One of the most important interactions to know about involves oral contraceptives. Because tirzepatide slows down how quickly your stomach empties, birth control pills may not be absorbed as effectively. If you're on the pill, use a backup method like condoms for at least 4 weeks after you start tirzepatide or increase your dose.

If you're already taking insulin or sulfonylureas for diabetes, adding tirzepatide increases your risk of low blood sugar. Your doctor will likely need to adjust your other diabetes medications when you start tirzepatide.

For any medications you take by mouth that need to be absorbed quickly or at a specific level (like thyroid medications or certain antibiotics), consider taking them at least an hour before your tirzepatide dose.

Planning for Surgery or Medical Procedures

This is really important: always tell your healthcare provider that you're taking tirzepatide before any surgery or procedure that requires anesthesia. Because the medication slows down how quickly food leaves your stomach, there's an increased risk of aspiration (food or liquid entering your lungs) during anesthesia. Many surgeons and anesthesiologists now recommend stopping GLP-1 medications like tirzepatide for a period before surgery — typically one to two weeks, though this can vary. Don't stop taking your medication on your own; work with your healthcare team to create a safe plan.

Tirzepatide Dosage Conversion Chart (mg to Units)

Quick reference showing how many units to draw for each dose at common vial concentrations. Find your concentration across the top, your dose down the left, and read off the units.

Dose	5 mg/mL	10 mg/mL	15 mg/mL	20 mg/mL	30 mg/mL	40 mg/mL
2.5 mg	50	25	17	12.5	8	6
5 mg	100	50	33	25	17	12.5
7.5 mg	150*	75	50	37.5	25	19
10 mg	200*	100	67	50	33	25
12.5 mg	250*	125*	83	62.5	42	31
15 mg	300*	150*	100	75	50	37.5

*Doses exceeding 100 units (1mL) require a larger syringe or split injection.

Brand vs Compounded Tirzepatide

	Brand (Mounjaro/Zepbound)	Compounded
FDA Approved	Yes	No
Delivery	Pre-filled auto-injector	Vial + syringe
Dose Calculation	Not needed	Required
Cost (USA)	$900-1,100/month	$150-450/month
Cost (UK)	£150-250/month private	Limited availability
Availability	Limited (shortages)	Generally available

FAQs About Tirzepatide Dosage Calculations

Track Your Tirzepatide Journey with Lina

Stop calculating doses manually and never miss an injection. Lina is the companion app built specifically for GLP-1 medications.

Dose tracking

Smart reminders

Progress tracking

Titration schedule

Side effect logging

Protein tracking

More GLP-1 tools

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Data Sources & References

1.
Calculation Formula
Units = (Target Dose mg ÷ Concentration mg/mL) × 100. Based on U-100 insulin syringe standard where 100 units = 1mL.
2.
FDA Zepbound Prescribing Information
accessdata.fda.gov/drugsatfda_docs/label/2023/217806s000lbl.pdf
3.
FDA Mounjaro Prescribing Information
accessdata.fda.gov/drugsatfda_docs/label/2022/215866s000lbl.pdf
4.
SURMOUNT-1 Clinical Trial
Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med. 2022;387(3):205-216.
nejm.org/doi/full/10.1056/NEJMoa2206038