Basal metabolic rate (Kleiber) calculator

Reviewed by the CalculatorHub team, edited by James Graham. Method: a standard formula rather than a jurisdiction-specific rule. How we document and test our methods. Last verified 2026-06-22.

The Basal metabolic rate (Kleiber) calculator computes basal metabolic rate (kleiber) from the relation BMR = 70 M^0.75 (kcal/day). It takes a single input (body mass in kg) and returns the metabolic rate in kcal/day. It is written for biology students, laboratory technicians and field researchers who want a quick, repeatable figure when planning a culture or a dilution series, working through a growth, inheritance or sequence problem, or comparing organisms and populations of different sizes. Enter your values below and the result updates instantly, and you can share a permalink that pre-fills the exact calculation. Keep your units consistent across every input, using a single time unit wherever a rate or an interval appears and matching length, area and volume units wherever a ratio is involved, enter measured values rather than rounded ones so that any rounding happens only at the end, and when a count comes from a sample rather than the whole, such as a hemocytometer field or a survey plot, keep track of the factor that scales it back up. For example, with body mass = 1 kg, the metabolic rate works out to 70 kcal/day, and the worked example further down the page shows every step so you can follow the arithmetic and reproduce it by hand. This is a standard formula rather than a jurisdiction-specific rule, so it does not depend on an external rate or schedule, and the figure above each result carries the date it was last verified. The figure follows from the numbers you enter, and living material rarely holds that still: growth slows as nutrients run down and waste accumulates, rates shift with temperature, and individuals vary within any population, so treat the result as a working figure and expect what you see at the bench or in the field to sit near it rather than exactly on it.