Resting Metabolic Rate Calculator (Cunningham)
RMR from fat-free mass via the Cunningham equation
🔒 Local only · Method · · Disclaimer · Resting Metabolic Rate Calculator (Cunningham)
Resting Metabolic Rate Calculator (Cunningham) is built for RMR from fat-free mass via the Cunningham equation — fast, free, and private. You supply Fat-Free Mass (kg) to Resting Metabolic Rate Calculator (Cunningham); the answer follows at once. Resting Metabolic Rate Calculator (Cunningham) displays each intermediate figure as well. Anyone comparing options in Fitness & Exercise can use Resting Metabolic Rate Calculator (Cunningham) to compare scenarios. Nothing is uploaded while Resting Metabolic Rate Calculator (Cunningham) works, and the figures stay put. Resting Metabolic Rate Calculator (Cunningham) handles resting metabolic rate calculator cunningham fat free mass rmr the same way as related figures — one of the Fitness & Exercise tools on CalcProMaster. No sign-up or email — Resting Metabolic Rate Calculator (Cunningham) answers as you type.
What the defaults give
60 kg of fat-free mass gives a resting metabolic rate of 1,820 kcal a day.
That is 500 plus 22 × 60, and it is the energy burned at complete rest.
The formula
RMR = 500 + 22 × fat-free mass in kg
Cunningham works from lean mass rather than total weight, which is why it is the preferred equation for athletes and anyone with a body composition measurement. Fat-free mass is everything that is not fat: muscle, bone, organs, water. If you only know body fat percentage, FFM = weight × (1 − body fat %).
Worked examples
60 kg FFM → 500 + 1,320 = 1,820 kcal
50 kg FFM → 1,600 kcal
70 kg FFM → 2,040 kcal
45 kg FFM → 1,490 kcal
80 kg FFM → 2,260 kcal
55 kg FFM → 1,710 kcal
RMR is not your daily burn
1,820 kcal is what you would burn lying still all day. Add daily activity and the number rises by 20% to 90% depending on how you live and train: a desk worker might total 2,200, an athlete in heavy training 3,500. The multiplier is the same activity factor used with BMR equations, and it is where most of the error in any calorie estimate comes from.
RMR also rises with muscle and falls with dieting. A long deficit lowers it by more than the loss of lean mass alone would predict — the body reduces spontaneous movement and hormonal output — which is why weight loss slows even when intake is unchanged. That adaptation is not in any equation.
Why Cunningham beats weight-based formulas for athletes
Equations such as Mifflin-St Jeor use total body weight, so two people at 90 kg get nearly the same answer even if one is 10% body fat and the other 30%. Cunningham uses the tissue that actually burns energy at rest, so the lean athlete correctly gets the higher figure. For someone carrying a lot of fat, it also avoids overestimating the metabolic contribution of that mass.
The catch is the input. Fat-free mass from a bathroom scale is an estimate, and the error propagates directly: 5 kg of error in FFM is 110 kcal a day. Use a DEXA scan or a careful caliper protocol if the number matters, and treat the result as a starting point to calibrate against two weeks of real weight data rather than a precise measurement.
Frequently Asked Questions
What is the Cunningham equation?
RMR = 500 + 22 × fat-free mass in kilograms. At 60 kg of lean mass it gives 1,820 kcal a day.
How is this different from BMR?
The value is similar but derived from lean mass rather than total weight, so it is more accurate for muscular or very lean people.
How do I get fat-free mass?
Subtract fat mass from body weight, or multiply weight by (1 − body fat %). A DEXA scan is the most accurate common method.
Is 1,820 kcal my daily calorie needs?
No, it is resting needs only. Multiply by an activity factor of 1.2 to 1.9 to get daily total expenditure.
Why does my metabolism slow when dieting?
A deficit reduces lean mass and also lowers spontaneous activity and hormone output. That adaptation goes beyond what the lean-mass equation predicts.
Plank Hold Standards and other Fitness tools
Plank Hold Standards · Cycling Cadence Calculator · Workout Rest Timer · Race Time Predictor · Pull-Up Test Standards · Muscle Gain Calculator · Fitness Guides