Our methodology

Every calculator on this site follows the same process. This page describes it so you can judge the numbers rather than trust them.

1. The formula comes first

Each tool starts from a published veterinary formula or dose threshold, not from an average of what other calculator sites say. Where a formula has a well-known simplified form and a more accurate one, we use the accurate one. The daily calorie tool, for example, uses the exponential resting energy equation rather than the linear approximation, because the linear version is only valid for mid-sized dogs.

2. Sources are named on the page

The reference for each constant appears on the tool page itself, under the formula. We prefer primary veterinary sources: WSAVA and AAHA guidelines, the National Research Council nutrient requirements, the Merck Veterinary Manual, and peer-reviewed papers. Where a figure comes from a poison control centre, we say which one.

3. The maths is separated from the interface

Every formula lives in its own module with no reference to the page it appears on. That separation exists so the calculations can be tested directly, and so the same function can be reused by other tools without being copied and quietly changed.

4. The maths is unit tested

Each formula module ships with tests that assert known worked examples, check the behaviour at boundaries, and reject invalid input. Tests also guard against specific classes of error we consider dangerous. The chocolate module, for instance, has a test asserting that every theobromine concentration is expressed per gram, because most published tables use milligrams per ounce and confusing the two would understate a dose by a factor of 28.

5. Invalid input produces an error, not a number

If you enter a body weight of zero, a negative amount, or a figure outside the range the formula is valid for, the tool says so. It does not display a plausible-looking result computed from nonsense. A silently wrong feeding amount or toxic dose is worse than no answer at all.

6. Uncertainty is stated, not smoothed over

Some questions do not have a precise answer. Energy requirements vary by roughly 20% between individual dogs of the same weight and lifestyle. Grape toxicity has no established dose threshold at all. Where that is the case, the page says so and shows a range or a warning instead of a false single figure.

7. Nothing you enter leaves your browser

Every calculation runs on your own device. Weights, ages and amounts are never transmitted to a server, because there is no server to transmit them to; these are static pages.

What this is not

These tools are built carefully, but they are not a veterinary examination, and they are not written by a veterinarian. They cannot account for your dog's medical history, medication or breed-specific risks. Read the medical disclaimer, and see the full list of sources.