# Pet medication dose converter

> Enter your pet’s body weight, the dose rate your veterinarian provided (mg/kg), and the liquid concentration (mg/mL) from the product label to get the single dose in mg and the volume to draw up in mL.

## Who stands behind this calculator

Written by [Patrick Li](/authors/patrick-li/). Editorially reviewed 2026-09-01 · Evidence checked 2026-09-01.

Evidence: Multiple sources agree · Evidence from this species.

No veterinarian has reviewed this page. It is educational guidance checked by the author against the cited sources — for health decisions, talk to your vet.

PetGuideCalc reserves its highest trust label for pages that a named veterinary professional has reviewed. This page does not carry that label.

The converter performs unit arithmetic only. It does not choose, check, or adjust a dose — the mg/kg rate comes from the prescribing veterinarian and the product label, and confirming the drawn volume is part of that instruction.

> ⚠ Medical disclaimer · Dosage outputs are unit conversions — not prescribing or diagnostic advice. Always confirm with the prescribing veterinarian and the licensed product label before administering any drug.

## How does the medication dose converter work?

For a 4.5 kg cat at 5 mg/kg the calculator returns 22.5 mg per dose. Add the 25 mg/mL liquid concentration and the same cat dose becomes 0.90 mL, closest tick = 1 mL syringe. For a 22 lb dog at 2 mg/kg the converter first translates 22.0 lb to 9.98 kg, then returns 19.96 mg / 0.40 mL per dose. Tablets and capsules need only the mg output: a 0.4 kg hamster at 25 mg/kg needs 10.0 mg per dose.

Use the interactive calculator on the page: https://petguidecalc.com/tools/medication-dose/ — enter body weight (kg or lb), the dose rate your veterinarian gave you (mg/kg), and the liquid concentration from the product label (mg/mL) to get the single dose in mg and the volume to draw up in mL.

## Worked examples

| Setup | Weight | Dose rate | Single dose | Volume | Tick |
|---|---|---|---|---|---|
| Cat · 5 mg/kg · 25 mg/mL oral suspension | 4.500 kg | 5 mg/kg | 22.50 mg | 0.90 mL | 1 mL syringe |
| Dog · 22 lb · 2 mg/kg · 50 mg/mL injectable | 9.98 kg (22 lb) | 2 mg/kg | 19.96 mg | 0.40 mL | 0.5 mL syringe |
| Hamster · 0.4 kg · 25 mg/kg · tablets | 0.400 kg | 25 mg/kg | 10.00 mg | — | N/A (tablets) |

## How the conversion works

Single dose (mg) = body weight (kg) × dose rate (mg/kg). When the input is in pounds, the converter applies the international avoirdupois constant 1 lb = 0.45359237 kg so the math always runs in SI units.

Volume (mL) = single dose (mg) ÷ liquid concentration (mg/mL). When you skip the concentration the calculator returns only the mg result — that is the right answer for tablets, capsules, or scored pills that do not need a liquid draw-up volume.

The syringe tick hint picks the nearest common oral syringe mark (0.1 / 0.25 / 0.5 / 1 / 2 / 5 mL). Above 5 mL the hint stops — at that point the prescribing label usually asks you to split the dose across multiple draws.

Inputs outside the typical pet range do not block the math: the converter returns the value and adds a warning so the operator can confirm with the prescribing veterinarian. The tool does not validate that a dose is safe, appropriate, or labeled.

## Dosing questions, answered

**Q: Is this a prescribing tool?**

No. The calculator is a unit converter only. It does not tell you what dose is safe, what drug is appropriate, or whether a drug is labeled for your pet. The dose rate must come from your prescribing veterinarian and the licensed product label.

**Q: Where does the dose rate (mg/kg) come from?**

The dose rate is a value your veterinarian gives you from the prescribing context — common ranges appear in the Merck Veterinary Manual dosage-calculation section and WSAVA Therapeutic Guidelines. This page never invents or recommends one.

**Q: Do I have to enter a concentration?**

No. Leave the concentration blank for tablets, capsules, or scored pills — the converter returns the mg result only. For an oral suspension or injectable, the concentration is on the product label and lets the tool give you a volume in mL.

**Q: Can I enter pounds?**

Yes. Toggle the weight unit to lb and the converter automatically applies 1 lb = 0.45359237 kg before the formula runs. The result still shows both kg and lb in the summary so you can verify.

**Q: Why is the result shown next to a yellow bar?**

Because the converter does unit math only, the page surfaces a medical disclaimer (MEDICAL_DISCLAIMER) near the calculator: dosage outputs are not prescribing or diagnostic advice — always confirm with the prescribing veterinarian and the licensed product label before giving any drug.

## Related calculators

- [All pet care tools](/tools/)
- [Reptile UVB calculator](/reptile/uvb-calculator/)

## Sources

The converter only does unit math; the dose rate itself must come from the prescribing label or your veterinarian. The two references below back the formula and the mg/kg ↔ mg/mL vocabulary used across veterinary formularies.

- [Dosage Calculation (Merck Veterinary Manual)](https://www.merckvetmanual.com/clinical-pharmacology/pharmacotherapeutics/dosage-calculation) — Merck Veterinary Manual, merckvetmanual.com, no date. Source for the formula dose (mg) = body weight (kg) × dose rate (mg/kg) and the volume to draw-up relationship mg ÷ mg/mL = mL.
- [WSAVA Therapeutic Guidelines (Global Nutrition & Pharmacology context)](https://wsava.org/global-guidelines/) — World Small Animal Veterinary Association, wsava.org, no date. Authoritative context for how mg/kg dosing and liquid concentration labels are framed in companion-animal practice.

_Educational resource, not veterinary advice. PetGuideCalc — https://petguidecalc.com_