Estimating your burn — BMR, activity, and the honest middle
Your daily burn is not one exact number. The BMR formula is a population average, and activity guesses are loose. Burnie uses your BMR plus your phone's active calories, and you tune the rest by watching your weight trend.
You want to know how many calories you burn in a day. So you open a calculator. You type your weight and height. You pick 'moderately active.' You get a clean number like 2,200. It looks exact. It is not. That number is a rough guess. Here is how to think about it honestly. Burnie helps you land in the middle.
Your BMR is a formula guess, not a measurement
Your BMR on Burnie comes from the Mifflin-St Jeor formula. It is the best formula we have. In a study of 337 adults, 82 percent were within 10 percent of measured value. That sounds great. But about 1 in 5 people were off by more than 10 percent. For obese adults, only 75 percent were that close. So your BMR is a close guess, not a measurement. It is the honest starting point, not the final word.
I can calculate my exact daily burn to the single calorie.
mostly falseMostly false. Scientists tested 10 prediction equations against the gold standard. The gold standard is doubly labeled water. Every equation had more than 10 percent error at the individual level. Only about 43 percent of people were within 10 percent of their real burn. The researchers said precise prediction at the individual level remains a challenge. Part of the reason is NEAT — fidgeting and moving without exercise. It varies a lot between people. It even predicts who gains fat and who resists it. Your real daily burn is a band, not a dot.
How Burnie narrows the guess into a workable middle
Burnie splits your daily burn into two honest parts. Your BMR comes from the Mifflin formula. That is a good population guess. Your active calories come from your phone or Health Connect. Your phone counts your real steps and movement. Burnie works out your deficit as food minus (BMR plus active calories). The phone side is not a guess. It is measured. That narrows the band a lot. Burnie does not read your heart rate, sleep, or blood pressure. It uses your phone movement. You can type a manual number too. Burnie is free, with no paid tier.
Three ways to know your daily burn
Tune your number by watching results
The bottom line
Your daily burn is not one exact number. It is a band, and the band moves with your week. Burnie gives you a workable middle. BMR comes from a good formula. Active calories come from your real phone steps. Start there, watch the trend for two weeks, and tune by results. The number you measure is always better than the number you guess.