Units to mg Converter
100 units at a potency of 28.8 units per mg weigh about 3.47 mg.
Quick answer: Divide the units by the potency in units per mg. For example, 100 units at 28.8 units per mg is 3.472 mg, 10 units at 28.8 units per mg is 0.3472 mg and 50 units at 28.8 units per mg is 1.736 mg.
The units to mg formula
Milligrams equal units divided by the units in one milligram.
Micrograms equal that answer times 1,000.
Take 100 units at 28.8 units per mg. 100 ÷ 28.8 gives 3.472 mg.
Take 10 units at 28.8 units per mg. 10 ÷ 28.8 gives 0.3472 mg.
Units and weight
A unit measures biological strength, and a milligram measures weight. The potency says how many units sit in each milligram.
There is no single rate for every substance, so each needs its own potency (People’s Pharmacy: How Many Units in a Milligram).
How to convert units to mg step by step
- Find the potency in units per mg.
- Enter the units.
- Divide the units by the potency.
- Multiply by 1,000 for micrograms.
Example 1: 100 units at 28.8 units per mg
- Start with 100 units at 28.8 units per mg.
- 100 ÷ 28.8 = 3.472.
- The amount is 3.472 mg.
100 units at 28.8 units per mg = 3.472 mg
Example 2: 10 units at 28.8 units per mg
- Start with 10 units at 28.8 units per mg.
- 10 ÷ 28.8 = 0.3472.
- The amount is 0.3472 mg.
10 units at 28.8 units per mg = 0.3472 mg
Example 3: 50 units at 28.8 units per mg
- Start with 50 units at 28.8 units per mg.
- 50 ÷ 28.8 = 1.736.
- The amount is 1.736 mg.
50 units at 28.8 units per mg = 1.736 mg
Example 4: 500 units at 28.8 units per mg
- Start with 500 units at 28.8 units per mg.
- 500 ÷ 28.8 = 17.361.
- The amount is 17.361 mg.
500 units at 28.8 units per mg = 17.361 mg
Example 5: 100 units at 50 units per mg
- Start with 100 units at 50 units per mg.
- 100 ÷ 50 = 2.
- The amount is 2 mg.
100 units at 50 units per mg = 2 mg
Example 6: 1,000 units at 28.8 units per mg
- Start with 1,000 units at 28.8 units per mg.
- 1,000 ÷ 28.8 = 34.722.
- The amount is 34.722 mg.
1,000 units at 28.8 units per mg = 34.722 mg
The default of 28.8 is for human insulin. Insulin is dosed in units on the pen or syringe, never in mg.
units to mg conversion table
| Amount and potency | Milligrams (mg) | Micrograms (mcg) |
|---|---|---|
| 1 units at 28.8 units per mg | 0.0347 mg | 34.722 mcg |
| 5 units at 28.8 units per mg | 0.1736 mg | 173.61 mcg |
| 10 units at 28.8 units per mg | 0.3472 mg | 347.22 mcg |
| 25 units at 28.8 units per mg | 0.8681 mg | 868.06 mcg |
| 50 units at 28.8 units per mg | 1.736 mg | 1,736.11 mcg |
| 100 units at 28.8 units per mg | 3.472 mg | 3,472.22 mcg |
| 500 units at 28.8 units per mg | 17.361 mg | 17,361.11 mcg |
| 1,000 units at 28.8 units per mg | 34.722 mg | 34,722.22 mcg |
| 100 units at 50 units per mg | 2 mg | 2,000 mcg |
The highlighted row is the default of the calculator. The last column gives Micrograms (mcg).
A quick mental shortcut for units to mg
At 28.8 units per mg, divide the units by 30 for a close mg figure.
So 300 units is about 10 mg, and the exact figure is 10.4 mg.
Reading a certificate
A certificate may state the potency as units per mg. Divide the units you need by that number to find how much powder it takes.
Always use the number for your own batch.
Quick conversion answers
| Conversion | Result |
|---|---|
| 10 units at 28.8 units per mg | 0.3472 mg |
| 100 units at 28.8 units per mg | 3.472 mg |
| 1,000 units at 28.8 units per mg | 34.722 mg |
| 100 units at 100 units per mg | 1 mg |
Where this conversion is used
Lab and pharmacy staff turn a unit target into a weight of powder.
Students practise potency maths.
Common mistakes to avoid
- Multiplying instead of dividing. Weight equals units divided by potency.
- Using one potency for every substance. It differs.
- Mixing mg and mcg. 1 mg is 1,000 mcg.
- Weighing insulin at home. Insulin is dosed in units with the right device.
Related converters
More amounts at a glance
2 units at 28.8 units per mg is 0.06944 mg. 15 units at 28.8 units per mg is 0.5208 mg. 20 units at 28.8 units per mg is 0.6944 mg.
30 units at 28.8 units per mg is 1.042 mg. 75 units at 28.8 units per mg is 2.604 mg. 200 units at 28.8 units per mg is 6.944 mg.
250 units at 28.8 units per mg is 8.681 mg. 2,000 units at 28.8 units per mg is 69.44 mg. 100 units at 200 units per mg is 0.5 mg.
A note on safety
This page does the arithmetic for potency and unit sums. It is not medical advice.
Always follow your prescriber, pharmacist and the product label. If a number on the page does not match your label, trust the label and ask a professional.
Frequently asked questions
How many mg is 100 units at 28.8 units per mg?
About 3.47 mg.
How many mcg is 100 units at 28.8 units per mg?
About 3,472 mcg.
What is potency?
The number of units in one milligram.
Why is there no fixed rate?
Because each substance and batch differs.
Can I weigh insulin for a dose?
No. Insulin is dosed in units.
Is this medical advice?
No. Follow your prescriber and the label.
Sources
- People’s Pharmacy: How Many Units in a Milligram (library.peoplespharmacy.com)
- EMA: Potency labelling of insulin products (ema.europa.eu)
Medical note: This page is a unit converter, not medical advice. It does not tell you how much to take or to inject. Check your product label, and ask your doctor or pharmacist before you use any number from here.
Pens, vials and syringes differ in strength, and one unit can mean a different volume on each. Use only the product and the dose your prescriber gave you. If a result looks odd, stop and ask a pharmacist.
