無料BMR計算ツール

What does a BMR calculator tell you?

Your body needs energy even when your calendar is empty: breathing, circulation and maintaining tissues do not stop between workouts. Basal metabolic rate describes energy expenditure under tightly controlled resting conditions. A web calculator cannot recreate those laboratory conditions. It estimates resting energy from a small set of measurements instead.

The equation used here was developed to predict resting energy expenditure, often called RMR or REE. BMR and RMR are commonly grouped together in online tools, but their measurement conditions differ. Treat this number as a useful starting point, not a direct measurement of your metabolism.

How is BMR calculated?

Enter age in years, height and weight, then select the sex coefficient used in the equation. Metric inputs use kilograms and centimeters. Imperial inputs use pounds and total inches; 5 feet 7 inches is 67 inches. The calculator converts imperial measurements before applying the formula.

For the male coefficient: 10 × weight in kg + 6.25 × height in cm − 5 × age + 5. For the female coefficient, replace the final +5 with −161. The output is kilocalories per day, the same food-energy unit commonly written as Calories on US labels.

A worked BMR example

For a 30-year-old using the female coefficient at 70 kg and 170 cm, the calculation is 700 + 1,062.5 − 150 − 161 = 1,451.5 kcal per day. The result card rounds this to 1,452 kcal. Using the male coefficient with the same measurements gives 1,617.5, rounded to 1,618 kcal.

These are arithmetic examples, not a standard that every adult should match. A different body size, age or equation changes the answer. Switching between kg/cm and lb/in changes the displayed measurements, not the underlying meaning of resting energy.

BMR versus TDEE: which number should you use?

BMR estimates resting needs. Total daily energy expenditure, or TDEE, also accounts for everyday movement and activity. Two people with similar resting estimates can have very different total daily needs if their routines differ.

Use the linked TDEE calculator to explore an activity-based estimate before considering a daily food budget. Do not subtract a weight-loss deficit directly from BMR or treat the number as a universal minimum or maximum intake. Personal targets need context beyond an online equation.

Understand the estimate’s limits

The original Mifflin study included healthy adults aged 19–78. Individual prediction errors remain possible. Our form accepts adults aged 18–100 for practical use; allowing an input does not establish that the equation was validated for every age or circumstance.

Pregnancy, breastfeeding, illness, unusual body composition and intensive training can make generic estimates less suitable. If a result will guide a clinical decision, use qualified individual advice or a measured resting-energy assessment. Recheck your units before interpreting an unexpected number.

Turn an estimate into an easier daily habit

Once you understand resting and total energy, make logging the meal in front of you the easy part. BiteCal combines AI photo estimates, reviewable portions, calories and macros with a friendly white-bear companion. Start a free trial in the app and check the offer’s terms before subscribing.

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