Whether you are estimating on the spot or checking a result somebody else gave you, the cat bmi calculator is the quickest way to get from length of the lower back leg and rib cage circumference to fbmi.
What Is the Cat BMI Calculator?
The cat bmi calculator works out fbmi from length of the lower back leg and rib cage circumference.
Biological relationships are usually approximations rather than exact laws, so the output is best treated as an estimate with a sensible range around it.
How the Cat BMI Calculation Works
The calculation applies the relationship as published, step by step, so each intermediate value can be checked against the underlying theory.
Keep the units consistent throughout. Mixing a percentage with a proportion is the single most common source of an answer that is out by a factor of a hundred.
Assumptions Worth Knowing
Any relationship used here assumes a constant rate, a representative sample, or a stable population. Real populations rarely meet those conditions for long, so treat the answer as a guide.
Where the inputs are field measurements, a single misread value can shift the result noticeably. Measure carefully and record what you used.
A Worked Example
Working through an example, with length of the lower back leg set to 10, rib cage circumference set to 5, the calculator returns fbmi of -13.19. Substitute your own figures and the same steps produce the same kind of answer.
Frequently Asked Questions
What do I need to work out fbmi?
Enter length of the lower back leg and rib cage circumference. The calculator then works through the relationship and reports fbmi.
What does the cat bmi actually calculate?
It takes length of the lower back leg and rib cage circumference and converts them into fbmi using the standard relationship for this problem. Each step is applied in turn, so every output is traceable back to the numbers you typed in.
How should I enter length of the lower back leg?
Use the value you actually have, in the unit shown next to the field. Enter every value in the same unit system. The calculator assumes the figures you supply are consistent, so it cannot correct a mistake that happens before the calculation starts.
Why does a small change in one value move the answer so much?
That happens when an output depends on a ratio, because dividing by a small number magnifies any change in it. Check the units first, then check whether the value you entered is in the range the relationship was designed for.
Can I use this for a quick estimate as well as a precise answer?
Yes. The calculator is built for quick checks, so round your inputs to a sensible number of significant figures and the result will be just as useful. If you need more precision, keep the same method and add digits to the inputs rather than adjusting the method itself.