How do I convert a mg/kg dose into millilitres to inject?

First multiply the animal's weight in kilograms by the dose rate in mg per kg to get the total milligrams needed. Then divide that by the drug's concentration in mg per mL. The result is the volume in millilitres to draw. The tool does both steps for you.

Where do I find the dose rate and concentration?

Both are printed on the product label and package insert. The dose rate is given as mg per kg of body weight, sometimes per pound. The concentration is the strength of the solution, for example 200 mg per mL. Always use the figures for the specific product in hand.

Can I enter the animal's weight in pounds?

Yes. Switch the unit to pounds and the tool divides by 2.20462 to convert to kilograms before dosing, since label dose rates are usually expressed per kilogram. Accurate weight is critical, so weigh or band the animal rather than guessing.

Does this account for meat and milk withdrawal times?

No. This tool only calculates dose volume. Withdrawal periods before slaughter or for milk are set by the product label and your regulator and must be observed separately. Record every treatment with the product, dose, date, and withdrawal end.

Is this a substitute for veterinary advice?

No. Dosing, route, and choice of drug must follow the product label and the direction of your veterinarian, including any extra-label use which is legally restricted. This calculator only does the arithmetic; it does not validate the protocol.

Livestock Veterinary Drug Dose Calculator

Getting an injection volume wrong on a 600 kg cow or a 4 kg lamb is easy to do in your head at the chute. This calculator turns a label dose rate in mg/kg and a bottle concentration in mg/mL into the exact volume to draw for that animal’s weight.

How it works

Two steps, both pure arithmetic:

Total dose (mg) = body weight (kg) x dose rate (mg/kg)
Volume to draw (mL) = total dose (mg) divided by concentration (mg/mL)

If you enter weight in pounds, it is divided by 2.20462 to convert to kilograms first, because label dose rates are almost always per kilogram. Dividing dose by concentration cancels the milligrams and leaves millilitres.

Example

A 600 kg steer needs an antibiotic labelled at 10 mg/kg. Total dose is 600 x 10 = 6000 mg. The bottle is 200 mg/mL, so the volume is 6000 / 200 = 30 mL. Split across injection sites per the label if the volume exceeds the maximum per site.

Notes

This tool does the dose math only. Meat and milk withdrawal periods, route of administration, maximum volume per injection site, and any extra-label use are governed by the product label and your veterinarian. Record every treatment.