How do I convert a percentage to mg/mL?

Multiply the percentage by 10. A percentage strength means grams of drug in 100 mL, so 1% is 1 g in 100 mL, which is 1000 mg in 100 mL, which is 10 mg/mL.

How many mg are in 1 mL of 1% lidocaine?

10 mg. A 1% solution holds 10 mg in every millilitre.

What does 1:1000 mean on an adrenaline ampoule?

One gram of adrenaline in 1000 mL of solution, which is 1 mg/mL. The 1:10,000 presentation is 1 g in 10,000 mL, or 0.1 mg/mL, a tenth of the strength.

Is 0.9% sodium chloride the same as normal saline?

Yes, 0.9% sodium chloride is what normal saline means. It holds 9 mg of sodium chloride in every millilitre, or 9 g in a litre bag.

Percent to mg/mL Converter

Strength

– mg/mL

Enter a percentage or a ratio.

Total drug in the container: –
Also written as: –

The working

This works out the arithmetic. The order, the product in your hand and local policy still govern what is given.

What a percentage strength means

mg/mL = percentage × 10

A percentage strength on a medicine is weight in volume: grams of drug in 100 mL of solution. So 1% is 1 g in 100 mL. Converting the gram to 1000 mg and dividing by 100 gives 10 mg/mL, and that factor of ten holds for every percentage.

Percentage	Strength	In 10 mL
0.45%	4.5 mg/mL	45 mg
0.9%	9 mg/mL	90 mg
1%	10 mg/mL	100 mg
2%	20 mg/mL	200 mg
3%	30 mg/mL	300 mg
5%	50 mg/mL	500 mg
10%	100 mg/mL	1000 mg
20%	200 mg/mL	2000 mg
50%	500 mg/mL	5000 mg

What a ratio strength means

mg/mL = 1000 ÷ the second number

A ratio strength is one gram of drug in that many millilitres of solution. The notation predates modern labelling and survives mostly on adrenaline.

Ratio	Strength	Usually seen as
1:1,000	1 mg/mL	Adrenaline for intramuscular use in anaphylaxis
1:10,000	0.1 mg/mL	Adrenaline for intravenous use in cardiac arrest
1:100,000	0.01 mg/mL	Dilute adrenaline in local anaesthetic
1:200,000	0.005 mg/mL	Dilute adrenaline in local anaesthetic

The top two rows differ tenfold and are stocked side by side. Once the strength is in mg/mL, working out the volume for a dose is the ordinary mg to mL calculation, which draws the answer in a syringe so a tenfold slip is visible rather than only arithmetic.

Questions about percentage and ratio strengths

How do I convert a percentage to mg/mL?: Multiply the percentage by 10. A percentage strength means grams of drug in 100 mL, so 1% is 1 g in 100 mL, which is 1000 mg in 100 mL, which is 10 mg/mL.
How many mg are in 1 mL of 1% lidocaine?: 10 mg. A 1% solution holds 10 mg in every millilitre.
What does 1:1000 mean on an adrenaline ampoule?: One gram of adrenaline in 1000 mL of solution, which is 1 mg/mL. The 1:10,000 presentation is 1 g in 10,000 mL, or 0.1 mg/mL, a tenth of the strength.
Is 0.9% sodium chloride the same as normal saline?: Yes, 0.9% sodium chloride is what normal saline means. It holds 9 mg of sodium chloride in every millilitre, or 9 g in a litre bag.