How we source our numbers

Every number on this site comes from somewhere, and we tell you where. This page explains how we decide what to publish, because a calculator that will not show its working is just an opinion with a text box.

The rule

We do not publish a coefficient we cannot attribute to a named source.

In practice that means a university extension service, a peer-reviewed paper, a government agency, or a primary reference text such as the National Research Council’s Nutrient Requirements of Horses. A blog, a forum thread, a feed company’s marketing page, or another calculator is not a source. Those are where errors get copied from, not where they get fixed.

When we cannot find a real source for something, we say so on the page rather than filling the gap with a plausible-looking number.

What that changes in practice

Sometimes it means we disagree with everyone

Cold-weather feeding is a good example. Articles will tell you a horse needs one percent more energy for every degree Fahrenheit below its lower critical temperature. Others say two percent. Others say two and a half percent per degree Celsius, which is a different figure again.

All three are the same underlying coefficient from the National Research Council, rounded differently, and in at least one case with the temperature units swapped. We use the original figure and derive the rest from your horse’s own maintenance requirement, so our winter answer differs from most of what you will read elsewhere. The page shows the arithmetic so you can check it.

Sometimes it means we refuse to answer

A common question is what a flake of hay weighs. There is no measured, published answer. The closest thing we found was Penn State weighing three flakes from a single bale: they came out at 4.57 lb, 3.21 lb and 4.54 lb.

A forty-two percent spread inside one bale means any single published flake weight is fiction. So our calculator derives flake weight from your bale weight and your flakes per bale, and tells you why it will not simply give you a number.

Sometimes it means correcting ourselves

Our own working notes assumed round bales fed without a feeder waste twenty to forty percent of the hay. The measured figure, from a University of Minnesota study of twenty-five horses, is fifty-seven percent. We changed our number to match the evidence.

Where the numbers are shown

Each calculator page carries the formula written out, a worked example using real figures, and a list of sources at the bottom. If a page relies on a coefficient, that coefficient is named and cited on the page that uses it.

Where sources genuinely disagree, we say so and explain which one we followed. Where a figure is a rule of thumb rather than a measurement, we label it as one.

What we are not

We are not veterinarians, nutritionists, marine engineers or towing specialists. These calculators are reference tools built carefully from published research. They are not a substitute for professional advice, and they do not know anything about your specific animal, vehicle or vessel.

For anything involving an animal’s health, medication, or a load-bearing safety limit, treat the output as a starting point for a conversation with a qualified professional, not as an answer.

Corrections

If you think a number here is wrong, we want to know, particularly if you have a source. Send it to [email protected] with a link to the page. If you are right, we will change it and say what changed.