mg per kg Converter
500 mg shared across 70 kg of body weight is about 7.14 mg per kg.
Quick answer: Divide the amount in mg by the body weight in kg. For example, 500 mg, 70 kg is 7.143 mg/kg, 720 mg, 60 kg is 12 mg/kg and 750 mg, 15 kg is 50 mg/kg.
The mg per kg formula
Amount per kg equals the amount in mg divided by the body weight in kg.
Divide the kg figure by 2.2046 to get mg per lb.
Take 500 mg, 70 kg. 500 ÷ 70 gives 7.143 mg/kg.
Take 720 mg, 60 kg. 720 ÷ 60 gives 12 mg/kg.
Amount per kilogram
A weight-based amount is written in mg per kg. To get the total from a rate, multiply the body mass in kg by the rate, and the kg units cancel (RMIT Learning Lab: Medication dosage by body weight).
This page runs the sum the other way. It divides a known amount in mg by the weight in kg to find the rate.
How to convert mg per kg step by step
- Read the amount in mg.
- Read the body weight in kg.
- Divide the amount by the weight.
- Read the mg per lb in the last column, if you need it.
Example 1: 500 mg, 70 kg
- Start with 500 mg, 70 kg.
- 500 ÷ 70 = 7.143.
- The amount per kg is 7.143 mg/kg.
500 mg, 70 kg = 7.143 mg/kg
Example 2: 720 mg, 60 kg
- Start with 720 mg, 60 kg.
- 720 ÷ 60 = 12.
- The amount per kg is 12 mg/kg.
720 mg, 60 kg = 12 mg/kg
Example 3: 750 mg, 15 kg
- Start with 750 mg, 15 kg.
- 750 ÷ 15 = 50.
- The amount per kg is 50 mg/kg.
750 mg, 15 kg = 50 mg/kg
The three examples below use common sizes.
Each one shows the sum in full.
mg per kg conversion table
| Amount and weight | mg per kg | mg per lb |
|---|---|---|
| 60 mg, 12 kg | 5 mg/kg | 2.268 mg/lb |
| 100 mg, 50 kg | 2 mg/kg | 0.9072 mg/lb |
| 150 mg, 30 kg | 5 mg/kg | 2.268 mg/lb |
| 250 mg, 25 kg | 10 mg/kg | 4.536 mg/lb |
| 300 mg, 90 kg | 3.333 mg/kg | 1.512 mg/lb |
| 500 mg, 70 kg | 7.143 mg/kg | 3.24 mg/lb |
| 720 mg, 60 kg | 12 mg/kg | 5.443 mg/lb |
| 750 mg, 15 kg | 50 mg/kg | 22.68 mg/lb |
| 1,000 mg, 80 kg | 12.5 mg/kg | 5.67 mg/lb |
| 200 mg, 40 kg | 5 mg/kg | 2.268 mg/lb |
| 400 mg, 50 kg | 8 mg/kg | 3.629 mg/lb |
| 900 mg, 75 kg | 12 mg/kg | 5.443 mg/lb |
The highlighted row is the default of the calculator. The last column gives mg/lb.
A quick mental shortcut for mg per kg
If the amount is 10 times the weight in kg, the rate is 10 mg/kg. For example, 600 mg at 60 kg is 10 mg/kg.
Double the amount and the rate doubles. Double the weight and the rate halves.
Worked examples
720 mg at 60 kg is 12 mg/kg, and 750 mg at 15 kg is 50 mg/kg. These match the worked examples in the RMIT guide, which multiply 12 mg/kg by 60 kg to get 720 mg and 50 mg/kg by 15 kg to get 750 mg (RMIT Learning Lab: Medication dosage by body weight).
100 mg at 50 kg is 2 mg/kg, and 250 mg at 25 kg is 10 mg/kg.
Kilograms and pounds
One pound avoirdupois is exactly 0.45359237 kg (ProofWiki: Pound Avoirdupois). So 1 kg is about 2.2046 lb, and mg/lb is mg/kg divided by 2.2046.
For 500 mg at 70 kg, the rate is 7.1429 mg/kg, which is about 3.24 mg/lb.
Keep the time frame
A rate often comes with a time frame, such as per day or per dose. Never drop it from the answer (RMIT Learning Lab: Medication dosage by body weight).
This page does not know the time frame, so you must keep track of it yourself.
Safety note
This page is for information only and is not medical advice. It does not know the drug, the age, the condition or the safe range.
Always check any dose or calculation with a pharmacist, a doctor or your local protocol before you act on it.
Quick conversion answers
| Conversion | Result |
|---|---|
| 500 mg, 70 kg | 7.143 mg/kg |
| 720 mg, 60 kg | 12 mg/kg |
| 750 mg, 15 kg | 50 mg/kg |
| 100 mg, 50 kg | 2 mg/kg |
Where this conversion is used
Students practise weight-based sums.
Pet owners, nurses and carers can check a sum, then confirm it with a professional.
Common mistakes to avoid
- Using this as dose advice. Always confirm with a professional.
- Dropping the time frame. Per day and per dose are not the same.
- Mixing kg and lb. Use kg for the main answer.
- Mixing mg with g or mcg. Convert to mg first.
Related converters
More amounts and weights
50 mg, 10 kg is 5 mg/kg. 120 mg, 20 kg is 6 mg/kg. 180 mg, 45 kg is 4 mg/kg.
350 mg, 70 kg is 5 mg/kg. 600 mg, 60 kg is 10 mg/kg. 800 mg, 80 kg is 10 mg/kg.
1,200 mg, 60 kg is 20 mg/kg. 1,500 mg, 75 kg is 20 mg/kg. 2,000 mg, 100 kg is 20 mg/kg.
Doubling the first number
100 mg, 10 kg is 10 mg/kg. 240 mg, 20 kg is 12 mg/kg. 360 mg, 45 kg is 8 mg/kg.
700 mg, 70 kg is 10 mg/kg. 1,200 mg, 60 kg is 20 mg/kg. 1,600 mg, 80 kg is 20 mg/kg.
2,400 mg, 60 kg is 40 mg/kg. 3,000 mg, 75 kg is 40 mg/kg. 4,000 mg, 100 kg is 40 mg/kg.
Frequently asked questions
How do I calculate mg per kg?
Divide the amount in mg by the body weight in kg.
What is 500 mg at 70 kg in mg/kg?
About 7.14 mg/kg.
How do I get the total from a mg/kg rate?
Multiply the rate by the body weight in kg.
How do I convert mg/kg to mg/lb?
Divide by 2.2046.
Is this medical advice?
No. Always check with a pharmacist or doctor.
Why keep the time frame?
Because per day and per dose are different amounts.
Sources
- RMIT Learning Lab: Medication dosage by body weight (learninglab.rmit.edu.au)
- ProofWiki: Pound Avoirdupois (proofwiki.org)
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.
