Free Tirzepatide Calculator
Tirzepatide Dose Calculator
Review the standard weekly Mounjaro or Zepbound schedule, see where your prescribed dose fits, or convert a prescribed vial dose from milligrams to millilitres and U-100 syringe units.
- Covers 2.5 mg through 15 mg weekly
- Based on current US prescribing information
- No sign-up required
- Calculations run in your browser
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Your Tirzepatide Calculator Results
Your result shows the prescribed weekly dose, calculated liquid volume, U-100 syringe marking, concentration used and the complete formula. It also shows the next scheduled injection date when a valid date is provided.
Match the dose, concentration, volume and syringe marking with the instructions on your prescription label. If any value differs, stop and contact the dispensing pharmacy before injecting.
- Your prescribed weekly dose in mg
- Your calculated volume in mL
- Your U-100 syringe marking
- The concentration used in mg/mL
- The calculation used to produce the result
- Your next scheduled injection date
How to Calculate a Tirzepatide Dose in mg, mL and Units
Milligrams describe the amount of tirzepatide, while millilitres describe the liquid volume. A concentration such as 10 mg/mL tells you how many milligrams are present in each millilitre. U-100 units are volume markings, with 100 units equal to 1 mL.
To verify a prescribed vial dose, divide the prescribed dose in mg by the concentration in mg/mL. This gives the volume in mL. For a confirmed U-100 insulin syringe, multiply that volume by 100 to find the syringe marking.
For example, a prescribed 5 mg dose from a 10 mg/mL vial equals 0.5 mL. On a U-100 syringe, 0.5 mL reaches the 50-unit marking. This is an arithmetic example, not a dose recommendation.
- Volume in mL = prescribed dose in mg ÷ concentration in mg/mL
- U-100 syringe units = volume in mL × 100
- Never calculate from another person's unit amount
Safety check: a different vial concentration produces a different liquid volume and syringe marking for the same milligram dose.
Compounded Tirzepatide Dosage Calculator Safety
Compounded tirzepatide is not FDA-approved, and concentrations can vary between pharmacies. The FDA does not verify the safety, effectiveness or quality of compounded drugs before marketing and has reported adverse events associated with compounded tirzepatide.
Use the conversion calculator only when the label clearly states tirzepatide, the concentration in mg/mL, the prescribed dose in mg and the pharmacy's volume or syringe instructions. Do not use it when the total liquid volume is missing or when the label is unclear.
- Confirm tirzepatide is the active ingredient
- Confirm the concentration in mg/mL
- Confirm the prescribed dose in mg
- Confirm the pharmacy's volume or U-100 syringe marking
- Stop and call the pharmacy if the calculated answer differs
The word units describes syringe volume, not tirzepatide strength. Never copy a unit amount from another patient or another vial.
Tirzepatide Dosing Schedule for Mounjaro and Zepbound
The usual starting dose is 2.5 mg once weekly for 4 weeks, followed by 5 mg once weekly. If additional response is needed and the current dose is tolerated, a prescriber may increase the dose in 2.5 mg steps after at least 4 weeks on the current strength. The maximum recommended adult dose is 15 mg weekly.
This is a labelled schedule, not a target everyone must follow. Four weeks is the minimum time before a possible increase. It is not a requirement to increase every month.
| Treatment period | Weekly dose | What it means |
|---|---|---|
| Weeks 1 to 4 | 2.5 mg | Starting dose for treatment initiation |
| Week 5 onward | 5 mg | First usual maintenance dose |
| After at least 4 weeks on 5 mg | 7.5 mg | Possible escalation step if needed |
| After at least 4 weeks on 7.5 mg | 10 mg | Maintenance option for Zepbound and possible Mounjaro dose |
| After at least 4 weeks on 10 mg | 12.5 mg | Possible escalation step if needed |
| After at least 4 weeks on 12.5 mg | 15 mg | Maximum recommended weekly dose |
Mounjaro Dose Calculator
Mounjaro contains tirzepatide and is FDA-approved to improve glycaemic control in people aged 10 years and older with type 2 diabetes, alongside diet and exercise. The adult starting dose is 2.5 mg once weekly for 4 weeks, followed by 5 mg once weekly.
The 2.5 mg dose is intended for initiation and is not intended for glycaemic control. If additional control is needed, the adult dose may increase in 2.5 mg steps after at least 4 weeks on the current dose, up to 15 mg weekly. Anyone under 18 should follow the prescribed paediatric instructions rather than an adult calculator schedule.
Zepbound Dose Calculator for Weight Loss
Zepbound contains tirzepatide and is FDA-approved for chronic weight management in eligible adults and for obstructive sleep apnea in adults with obesity. It uses the same 2.5 mg starting dose and 2.5 mg escalation steps.
For weight management, 5 mg, 10 mg and 15 mg are recommended maintenance doses. For obstructive sleep apnea in adults with obesity, 10 mg and 15 mg are recommended maintenance doses. The selected dose should reflect response and tolerability. A higher dose is not automatically the right dose, and 15 mg is a maximum rather than a goal.
When Should a Tirzepatide Dose Increase Be Considered?
The official schedule gives the earliest time at which an increase may be considered. It does not make every increase automatic. A prescriber considers time on the current strength, response, side effects, other medicines and any treatment interruptions.
Do not increase because another person lost more weight at a higher dose. Trial averages and community experiences cannot predict an individual response.
- At least 4 weeks on the current strength
- Glycaemic response when used for type 2 diabetes
- Weight-management response when used for obesity
- Nausea, vomiting, diarrhoea, constipation or abdominal symptoms
- Use of insulin, sulfonylureas or other medicines
- Any gap since the previous injection
Can You Stay on 5 mg Tirzepatide Longer Than 4 Weeks?
Yes. A person may remain on 5 mg when the prescriber decides it is effective and tolerated. For Zepbound weight management, 5 mg is one of the recommended maintenance doses.
The label requires at least 4 weeks at a dose before a further increase, but it does not require an increase every 4 weeks. The correct decision depends on treatment goals, response, side effects and other medicines.
Tirzepatide Missed Dose Calculator
If a Mounjaro or Zepbound dose is missed and 4 days or fewer have passed, take it as soon as possible. If more than 4 days have passed, skip it and take the next dose on the regularly scheduled day. Never take two doses within 72 hours of each other.
After several missed weekly doses, contact the prescriber before restarting. The product label does not provide one restart strength for every longer interruption, and gastrointestinal tolerance may have changed.
Can You Change Your Tirzepatide Injection Day?
The weekly injection day may be changed as long as at least 72 hours have passed between two doses. Continue once weekly on the new day after the change.
For example, after a Monday injection at 8:00 AM, the earliest time permitted by the 72-hour rule is Thursday at 8:00 AM. This shows the minimum interval, not a recommendation to move the dose earlier.
How Long Does Tirzepatide Stay in Your System?
Tirzepatide has an elimination half-life of about 5 days, and steady-state concentrations are reached after about 4 weeks of once-weekly administration. The full effect and tolerability of a new dose cannot always be judged from the first injection.
Any drug-activity percentage shown by this calculator is an educational pharmacokinetic estimate. It is not a blood-level measurement and should not be used to change a dose or injection date.
Mounjaro vs Zepbound Dose: Is the Schedule the Same?
Mounjaro and Zepbound both contain tirzepatide and use the same available weekly strengths from 2.5 mg to 15 mg. Their FDA-approved uses and maintenance-dose wording differ.
| Feature | Mounjaro | Zepbound |
|---|---|---|
| Active ingredient | Tirzepatide | Tirzepatide |
| Main FDA-approved use | Type 2 diabetes | Chronic weight management and obstructive sleep apnea in adults with obesity |
| Starting dose | 2.5 mg weekly for 4 weeks | 2.5 mg weekly for 4 weeks |
| Dose increases | 2.5 mg after at least 4 weeks if needed | 2.5 mg after at least 4 weeks if needed |
| Maximum adult dose | 15 mg weekly | 15 mg weekly |
| Maintenance approach | Based on glycaemic response and tolerability | 5, 10 or 15 mg for weight management; 10 or 15 mg for obstructive sleep apnea |
Important Tirzepatide Safety Information
Tirzepatide has a boxed warning about thyroid C-cell tumours observed in rats. It is unknown whether tirzepatide causes these tumours in humans. Do not use Mounjaro or Zepbound if you or a family member has had medullary thyroid carcinoma or if you have Multiple Endocrine Neoplasia syndrome type 2.
Contact a clinician promptly for severe or persistent abdominal pain, repeated vomiting, signs of dehydration, symptoms of gallbladder disease, a serious allergic reaction or significant vision changes. The risk of low blood sugar is higher when tirzepatide is used with insulin or an insulin secretagogue such as a sulfonylurea.
Tirzepatide delays gastric emptying and can affect absorption of some oral medicines. Current prescribing information advises people using oral hormonal contraceptives to switch to a non-oral method or add a barrier method for 4 weeks after starting tirzepatide and for 4 weeks after every dose increase.
- Never use the calculator to start, stop or change a medicine
- Never split a fixed-dose pen or count partial clicks using this calculator
- Never take two doses within 72 hours
- Seek urgent care for a severe allergic reaction or other emergency symptoms
On tirzepatide? See what happens next, week by week
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- Every injection and dose change, on one timeline
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Sources and references
This page is built from public clinical guidance and peer-reviewed research. Always confirm decisions with a licensed clinician.
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Frequently Asked Questions
Frequently Asked Questions
Common questions and answers about this calculator.
What is the starting dose of tirzepatide?
The usual starting dose of Mounjaro or Zepbound is 2.5 mg once weekly for 4 weeks. The usual next step is 5 mg once weekly. Follow the prescription provided by your clinician.
How do I calculate tirzepatide units from mg?
You cannot convert mg to units without knowing the concentration in mg/mL and confirming that the syringe is U-100. Divide the prescribed mg by mg/mL to get mL. Then multiply mL by 100 to get the U-100 syringe marking.
How many units is 2.5 mg of tirzepatide?
There is no single answer because it depends on the vial concentration. At 10 mg/mL, 2.5 mg equals 0.25 mL or 25 units on a U-100 syringe. At 20 mg/mL, it equals 0.125 mL or 12.5 U-100 units. Use only the concentration on your prescription label.
How many units is 5 mg of tirzepatide?
The answer depends on concentration. At 10 mg/mL, 5 mg equals 0.5 mL or 50 U-100 units. At 20 mg/mL, 5 mg equals 0.25 mL or 25 U-100 units. Never copy a unit amount from another person's vial.
Is 2.5 mg a therapeutic dose of tirzepatide?
The labels use 2.5 mg as the starting dose for treatment initiation. For Mounjaro, it is not intended for glycaemic control. For Zepbound, it is not one of the recommended maintenance doses.
Is 5 mg a maintenance dose?
For Zepbound weight management, yes. The recommended maintenance doses are 5 mg, 10 mg and 15 mg weekly. Mounjaro dosing is adjusted according to glycaemic response and tolerability.
Do I have to increase tirzepatide every month?
No. Four weeks is the minimum time before a possible increase. It is not a requirement to increase every month. Your prescriber should consider treatment response, side effects, other medicines and any interruption in treatment.
Can I skip from 5 mg to 10 mg?
The labelled titration schedule uses 2.5 mg increments after at least 4 weeks on the current dose. Do not skip a strength or change a prescribed dose without speaking with your clinician.
Can I split a tirzepatide pen dose or count KwikPen clicks?
Do not use this calculator to split a fixed dose, count partial clicks or extract medicine from a pen. Use the device exactly as its Instructions for Use direct and ask a pharmacist if anything about the prescribed device is unclear.
What should I do after missing tirzepatide for two or more weeks?
Contact your prescriber before restarting. The standard missed-dose instructions cover a dose within or beyond 4 days, but they do not provide one restart strength for every longer interruption.
Can I take tirzepatide early or change my injection day?
You may change the weekly dosing day if at least 72 hours have passed since the previous injection. Do not take two doses less than 72 hours apart.
What is the maximum tirzepatide dose?
The maximum recommended adult dose of Mounjaro or Zepbound is 15 mg once weekly. Reaching 15 mg is not a goal, and a prescriber may keep a patient at a lower tolerated maintenance dose.
Are Mounjaro and Zepbound doses equivalent?
Both contain tirzepatide and are available in the same milligram strengths. Their approved uses and recommended maintenance-dose wording differ, so follow the prescription for the product you were given.
Can this calculator choose my tirzepatide dose?
No. It reviews the standard schedule and checks arithmetic for a dose that has already been prescribed. It cannot start, stop, select or change a dose. Those decisions belong to the prescribing clinician.
Medical Disclaimer: Calqulate Vitals provides educational information and arithmetic checking based on current US prescribing information. It does not prescribe, diagnose or replace a pharmacist or clinician. Never use it to start, stop, select or change a medication dose. If the result differs from the pharmacy label, stop and contact the dispensing pharmacy before injecting.
Tool Information
August 2026
Dr. Jaydeep Sanghani
Meet Akabari
Dr. Jaydeep Sanghani
MBBS, MD, DNB(Anaesth.), PDCC(CCM), DrNB(CCM)
AIIMS Bhubaneswar · AIIMS Rishikesh
Critical care specialist and anesthesiologist with advanced training from AIIMS. Reviews health calculators at Calqulate to ensure medical accuracy and evidence-based standards.
About the authors
