Mounjaro UK units ↔ mL ↔ mg calculator (U-100)

Use this UK calculator to convert Mounjaro (tirzepatide) KwikPen values between U-100 units, mL, and mg (UK KwikPen doses are 0.6 mL). Syringes often show units rather than mL, which can be confusing — this tool does the maths for you in seconds.

This page is general information and arithmetic only, not medical or dosing advice. Always follow your prescriber and the official product information.

Device / region

This changes the conversion because dose volume differs between regions.

Pen strength

I want to convert from…

Units (U-100)

Results

Enter a value above to see results.

This calculator shows general arithmetic only, not dosing advice. Always follow your prescriber and official instructions.

Quick facts

U-100: 100 units = 1 mL (so 1 unit = 0.01 mL)
UK Mounjaro dose volume: 0.6 mL = 60 units
Doses per pen: 4 (total 2.4 mL per pen)
Strengths: 2.5, 5, 7.5, 10, 12.5, 15 mg per dose

Try the dose tracker free — log units, mL and mg with automatic UK conversions.

Get Started How the maths works ↓

UK quick facts

Dose volume per labelled injection (UK): 0.6 mL
Doses per pen: 4 → total 2.4 mL per pen
Available strengths (per labelled dose): 2.5, 5, 7.5, 10, 12.5, 15 mg

How the calculator works

Units are a way of measuring volume on a U-100 syringe (100 units = 1 mL). Pen strength changes the concentration (mg per mL), so the same number of units can contain a different amount of medicine depending on the pen.

Core formulas

The calculator uses three values: the pen strength in mg, the dose volume (0.6 mL for UK, 0.5 mL for US), and the U-100 definition (100 units = 1 mL).

mg per mL = pen strength ÷ dose volume
From units: mL = units ÷ 100, then mg = mL × mg per mL
From mL: units = mL × 100, then mg = mL × mg per mL
From mg: mL = mg ÷ mg per mL, then units = mL × 100

UK shortcut (because 0.6 mL = 60 units):

mg = (units ÷ 60) × pen strength

For example, 40 units from a 5 mg pen: (40 ÷ 60) × 5 ≈ 3.33 mg

Common conversions

This table shows the basic relationship between U-100 units and mL (the same for all pen strengths):

U-100 units to mL conversion (100 units = 1 mL)
Units (U-100)	mL
10	0.10
20	0.20
30	0.30
40	0.40
50	0.50
60	0.60

Master conversion table (UK)

Select a pen strength to see how many mg each volume contains, or view all strengths at once. The table uses the same formulas as the calculator above.

Show for:

UK Mounjaro conversion: units to mL and mg delivered (approx) for 5 mg pen
Units	mL	mg delivered (approx)
10	0.10	0.833
20	0.20	1.667
30	0.30	2.500
40	0.40	3.333
50	0.50	4.167
60	0.60	5.000

Target dose look-up (by pen strength)

Pick a target mg, then read across to find the approximate units for each pen strength. Values are rounded to the nearest whole unit for readability.

Target mg to units by pen strength (UK, 0.6 mL dose)
Pen strength	0.5 mg	1 mg	2.5 mg	3 mg	5 mg
2.5 mg	12 u	24 u	60 u	—	—
5 mg	6 u	12 u	30 u	36 u	60 u
7.5 mg	4 u	8 u	20 u	24 u	40 u
10 mg	3 u	6 u	15 u	18 u	30 u
12.5 mg	2 u	5 u	12 u	14 u	24 u
15 mg	2 u	4 u	10 u	12 u	20 u

*Exceeds one labelled dose volume (0.6 mL UK / 0.5 mL US).

Why real-world use can differ

The tables and calculator show pure arithmetic based on labelled dose volumes and strengths. In real-world use, device instructions matter. If the maths and the instructions ever conflict, the official instructions take priority.

The UK KwikPen is designed for four weekly injections of 0.6 mL each. The pen mechanism is calibrated for exactly four doses.
A small amount of liquid may remain after four doses to ensure accurate delivery. This overfill is not intended as an extra dose. The patient information leaflet instructs you to discard the pen after four uses.
There is an in-use time limit after first use (for example, discard after 21 days at room temperature), which can cap how much is usable from a pen.
Pens are designed for a set number of doses and you may be instructed to discard the pen even if liquid remains. The official instructions always take priority over the arithmetic.

Try the dose tracker free — log units, mL and mg with automatic UK conversions.

Get Started

FAQs

What is a U-100 syringe?▾

A U-100 syringe shows volume in 'units' where 100 units equals 1.00 mL. It is a fine-grained volume scale commonly used for insulin and aligns well with the UK Mounjaro dose volume of 0.6 mL (60 units).

How many units are in one UK Mounjaro dose?▾

One UK labelled dose is 0.6 mL. On a U-100 syringe that equals 60 units.

Does pen strength change how many units I need for the same mg?▾

Yes. Stronger pens pack more mg per mL, so you need fewer units (less volume) to reach the same mg. For example, about 3 mg is ~36 units from a 5 mg pen but ~18 units from a 10 mg pen.

Is this calculator medical advice?▾

No. This calculator shows general arithmetic based on labelled pen strengths and U-100 syringe markings. It is not dosing advice. Always follow your prescriber and official product instructions.

Why does the calculator show both UK and US options?▾

UK KwikPens deliver 0.6 mL per labelled dose (per EMA/EMC product information) while US single-dose pens deliver 0.5 mL (per FDA label). The different volumes change the mg-per-mL concentration, so the maths differs between regions.

Why is there liquid left after 4 doses?▾

UK KwikPens contain 2.4 mL (4 doses of 0.6 mL) but may include a small overfill to ensure accurate delivery. The pen mechanism is designed for exactly four doses. Any remainder exists to guarantee each dose is complete — it is not intended as an extra dose. The patient information leaflet instructs you to discard the pen after four uses.

What is the 'golden dose' or '5th dose'?▾

These are informal terms used online to describe the small amount of liquid that may remain in a Mounjaro KwikPen after the four labelled doses. The manufacturer's instructions say to discard the pen after four uses. The pen is not designed to accurately deliver a fifth dose, and the official patient information leaflet does not support using any remainder.

Should I use leftover medicine from a pen?▾

The official instructions for use say to discard the pen after four doses, even if liquid appears to remain. If you have questions about your pen or dosing, speak to your prescriber or pharmacist.

How can I check my pen is genuine?▾

The MHRA advises checking that your medicine comes from a registered pharmacy and that the packaging has no signs of tampering. Look for the correct batch number, expiry date, and MHRA Yellow Card information in the patient information leaflet. If anything looks unusual, report it via the MHRA Yellow Card scheme.

References

Mounjaro KwikPen Patient Information Leaflet (UK)

EMC — Mounjaro KwikPen PIL — 0.6 mL per dose, 4 doses per pen, storage and discard guidance.

European Medicines Agency

Mounjaro EPAR Product Information — full prescribing information including pen strengths and dose volumes.

British National Formulary (BNF)

BNF — Tirzepatide — NHS prescribing reference for tirzepatide (Mounjaro).

FDA Prescribing Information (US)

FDA — Mounjaro Label — US single-dose pen: 0.5 mL per injection.

MHRA — Falsified Medicines

MHRA — Fake or unlicensed medicines guidance — how to check your medicine is genuine.

Last reviewed: March 2026

Written by Anna Bromley, Healthcount Founder

← Back to Blog

Mounjaro UK units ↔ mL ↔ mg calculator (U-100)

This page is general information and arithmetic only, not medical or dosing advice. Always follow your prescriber and the official product information.

Device / region

This changes the conversion because dose volume differs between regions.

Pen strength

I want to convert from…

Units (U-100)

Results

Enter a value above to see results.

This calculator shows general arithmetic only, not dosing advice. Always follow your prescriber and official instructions.

Quick facts

U-100: 100 units = 1 mL (so 1 unit = 0.01 mL)
UK Mounjaro dose volume: 0.6 mL = 60 units
Doses per pen: 4 (total 2.4 mL per pen)
Strengths: 2.5, 5, 7.5, 10, 12.5, 15 mg per dose

Try the dose tracker free — log units, mL and mg with automatic UK conversions.

Get Started How the maths works ↓

UK quick facts

Dose volume per labelled injection (UK): 0.6 mL
Doses per pen: 4 → total 2.4 mL per pen
Available strengths (per labelled dose): 2.5, 5, 7.5, 10, 12.5, 15 mg

How the calculator works

Core formulas

The calculator uses three values: the pen strength in mg, the dose volume (0.6 mL for UK, 0.5 mL for US), and the U-100 definition (100 units = 1 mL).

mg per mL = pen strength ÷ dose volume
From units: mL = units ÷ 100, then mg = mL × mg per mL
From mL: units = mL × 100, then mg = mL × mg per mL
From mg: mL = mg ÷ mg per mL, then units = mL × 100

UK shortcut (because 0.6 mL = 60 units):

mg = (units ÷ 60) × pen strength

For example, 40 units from a 5 mg pen: (40 ÷ 60) × 5 ≈ 3.33 mg

Common conversions

This table shows the basic relationship between U-100 units and mL (the same for all pen strengths):

U-100 units to mL conversion (100 units = 1 mL)
Units (U-100)	mL
10	0.10
20	0.20
30	0.30
40	0.40
50	0.50
60	0.60

Master conversion table (UK)

Select a pen strength to see how many mg each volume contains, or view all strengths at once. The table uses the same formulas as the calculator above.

Show for:

UK Mounjaro conversion: units to mL and mg delivered (approx) for 5 mg pen
Units	mL	mg delivered (approx)
10	0.10	0.833
20	0.20	1.667
30	0.30	2.500
40	0.40	3.333
50	0.50	4.167
60	0.60	5.000

Target dose look-up (by pen strength)

Pick a target mg, then read across to find the approximate units for each pen strength. Values are rounded to the nearest whole unit for readability.

Target mg to units by pen strength (UK, 0.6 mL dose)
Pen strength	0.5 mg	1 mg	2.5 mg	3 mg	5 mg
2.5 mg	12 u	24 u	60 u	—	—
5 mg	6 u	12 u	30 u	36 u	60 u
7.5 mg	4 u	8 u	20 u	24 u	40 u
10 mg	3 u	6 u	15 u	18 u	30 u
12.5 mg	2 u	5 u	12 u	14 u	24 u
15 mg	2 u	4 u	10 u	12 u	20 u

*Exceeds one labelled dose volume (0.6 mL UK / 0.5 mL US).

Why real-world use can differ

The UK KwikPen is designed for four weekly injections of 0.6 mL each. The pen mechanism is calibrated for exactly four doses.
A small amount of liquid may remain after four doses to ensure accurate delivery. This overfill is not intended as an extra dose. The patient information leaflet instructs you to discard the pen after four uses.
There is an in-use time limit after first use (for example, discard after 21 days at room temperature), which can cap how much is usable from a pen.
Pens are designed for a set number of doses and you may be instructed to discard the pen even if liquid remains. The official instructions always take priority over the arithmetic.

Try the dose tracker free — log units, mL and mg with automatic UK conversions.

Get Started

FAQs

What is a U-100 syringe?▾

How many units are in one UK Mounjaro dose?▾

One UK labelled dose is 0.6 mL. On a U-100 syringe that equals 60 units.

Does pen strength change how many units I need for the same mg?▾

Yes. Stronger pens pack more mg per mL, so you need fewer units (less volume) to reach the same mg. For example, about 3 mg is ~36 units from a 5 mg pen but ~18 units from a 10 mg pen.

Is this calculator medical advice?▾

No. This calculator shows general arithmetic based on labelled pen strengths and U-100 syringe markings. It is not dosing advice. Always follow your prescriber and official product instructions.

Why does the calculator show both UK and US options?▾

Why is there liquid left after 4 doses?▾

What is the 'golden dose' or '5th dose'?▾

Should I use leftover medicine from a pen?▾

The official instructions for use say to discard the pen after four doses, even if liquid appears to remain. If you have questions about your pen or dosing, speak to your prescriber or pharmacist.

How can I check my pen is genuine?▾

References

Mounjaro KwikPen Patient Information Leaflet (UK)

EMC — Mounjaro KwikPen PIL — 0.6 mL per dose, 4 doses per pen, storage and discard guidance.

European Medicines Agency

Mounjaro EPAR Product Information — full prescribing information including pen strengths and dose volumes.

British National Formulary (BNF)

BNF — Tirzepatide — NHS prescribing reference for tirzepatide (Mounjaro).

FDA Prescribing Information (US)

FDA — Mounjaro Label — US single-dose pen: 0.5 mL per injection.

MHRA — Falsified Medicines

MHRA — Fake or unlicensed medicines guidance — how to check your medicine is genuine.

Last reviewed: March 2026

Written by Anna Bromley, Healthcount Founder

← Back to Blog