Why does 400 mg/5 mL equal 80 mg per mL?

Because the strength on the label describes a volume larger than one millilitre, so it has to be reduced before it is useful. Dividing the milligrams by the millilitres in the printed ratio gives 80 mg in every single millilitre, which is the number the syringe markings actually work with.

What if my bottle shows a different strength?

Use the strength in your hand, not the one you remember. Pharmacies substitute concentrations between refills, and pediatric and geriatric suspensions are the most common swaps. The calculator on this page accepts any dose, and the main converter accepts any concentration, so re-run the numbers whenever a new bottle comes home.

How should the volume be measured?

With the oral syringe or dosing cup dispensed with the medication. Kitchen teaspoons vary from roughly 2.5 mL to 7 mL, which is enough to turn a correct prescription into a wrong dose. Any volume with a decimal in it belongs in a syringe.

Is this chart safe for injections or insulin?

No. Insulin is dosed in units with a matched insulin syringe, and injectables should be drawn only by someone trained on that drug and device. This chart is for oral liquids, suspensions, and syrups.

Amoxicillin 400 mg/5 mL Dosage Chart (mg to mL)

A Amoxicillin 400 mg/5 mL liquid contains 80 mg in every millilitre, so 200 mg is 2.5 mL, 400 mg is 5 mL, and 800 mg is 10 mL. Divide the prescribed milligrams by 80 to get the volume to draw up.

How to use the Amoxicillin 400 mg/5 mL Dosage Chart (mg to mL)

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Prescribed dose (mg)

400 mg/5 mL dosage chart

Every row below assumes the bottle reads 400 mg/5 mL, which is 80 mg in each millilitre. Find the milligram dose you were told to give in the left column and draw up the volume beside it.

Milligram dose to millilitre volume at 400 mg/5 mL
Dose (mg)	Volume (mL)
25 mg	0.31 mL
50 mg	0.63 mL
75 mg	0.94 mL
100 mg	1.25 mL
125 mg	1.56 mL
150 mg	1.88 mL
200 mg	2.5 mL
250 mg	3.13 mL
300 mg	3.75 mL
400 mg	5 mL
500 mg	6.25 mL
625 mg	7.81 mL
750 mg	9.38 mL
875 mg	10.94 mL
1000 mg	12.5 mL

Millilitre volume to milligram dose at 400 mg/5 mL
Volume (mL)	Dose (mg)
0.25 mL	20 mg
0.5 mL	40 mg
1 mL	80 mg
1.5 mL	120 mg
2 mL	160 mg
2.5 mL	200 mg
3 mL	240 mg
5 mL	400 mg
7.5 mL	600 mg
10 mL	800 mg
15 mL	1200 mg
20 mL	1600 mg

Reading a 400 mg/5 mL label without second-guessing it

The most frequent error with this strength is treating the first number as milligrams per millilitre. A 400 mg/5 mL bottle is not a 400 mg/mL liquid unless the label says so; the ratio has to be divided down first. Getting that step wrong shifts the volume by five times in either direction, which is the difference between a dose that does nothing and one that needs a call to poison control.

A quick sanity check catches most of it: a single oral dose above roughly 20 mL or below 0.2 mL deserves a second look before it is given. If the number from the chart feels far off what the pharmacy handed you last time, confirm the strength on the new bottle rather than reusing the old volume.

Charts for other label strengths

For any strength not listed, use the full medication dose converter or turn the doses into a daily routine with the medication schedule planner. The formula behind every row is worked step by step in mg to mL dosage calculations.

Frequently Asked Questions

Disclaimer: This tool is for educational purposes only. Consult a healthcare professional for medical advice.