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A 70 kg adult who is 175 cm tall has a BMI of about 22.86. One misplaced unit can change that answer by a factor of ten thousand.

BMI and body-fat percentage answer different questions. Comparing them is useful only when you understand the measurements each one uses.

A small change in BMI may reflect a small weight change, a different measurement routine or a height-entry error. The formula helps separate these possibilities.

A resting-energy estimate is one component of daily energy use. Treating it as an automatic eating target skips an important step.

Changing one input at a time reveals what the equation assumes. It does not tell you exactly how an individual body will change over time.

Before comparing results, check the equation, units and whether an activity multiplier has already been applied.

An activity multiplier can move a maintenance estimate substantially. Consider work, commuting and routine movement as well as planned exercise.

Match energy units before comparing a food label with a daily calorie estimate. Kilocalories and kilojoules describe energy using different scales.

A maintenance-energy estimate is not a dynamic weight forecast. A calculated energy difference should not be presented as a guaranteed future change in kilograms.

The decimal part of a minute must be multiplied by 60 to become seconds. Reading it as hundredths produces an incorrect pace.

A target pace is a time budget, not a prediction of fitness. Check that the per-kilometre plan matches the full distance.

For unequal distances, combine total time and total distance. A simple average of the displayed pace numbers can be misleading.

This calculator adds 280 days to the first day of the last menstrual period. Choosing the correct starting date is essential to understanding the estimate.

It can perform the calendar calculation, but correct arithmetic does not make the underlying pregnancy estimate reliable for every cycle.

Weeks contain seven days, while calendar months vary in length. Day-based arithmetic avoids the errors caused by treating every month as four weeks.

Cycle length is the interval between the starts of two periods. It is different from the number of days bleeding lasts.

A fixed 28-day assumption may not describe your records. Look at observed intervals and preserve the variation instead of hiding it behind one date.

A predicted date can help with supplies and flexible plans. It cannot confirm ovulation or guarantee a period-free travel window.

Carbohydrate, protein and fat provide different amounts of energy per gram. Equal energy percentages therefore do not imply equal weights.

With fixed percentages, each nutrient amount changes in proportion to total energy. Holding one gram target fixed describes a different plan.

The familiar 4, 4 and 9 factors are useful for estimation. Serving definitions, rounding and other food components can prevent an exact match.

Circumference equations respond to measurement changes. Tape position, tension and mixed units can move the result without demonstrating a real change in body fat.

Body-fat percentage, fat mass and fat-free mass describe related quantities. Understanding the distinction matters more than displaying extra decimal places.

A circumference equation contains logarithms and fitted constants. Mixing units cannot be repaired by converting the final percentage.