---
title: "BMR Calculator"
description: "Calculate your Basal Metabolic Rate and daily calorie needs with personalized guidance for weight loss, muscle gain, or maintenance goals"
slug: "health/bmr-calculator"
tags: ["health", "fitness", "calories", "metabolism", "nutrition"]
author: "AgentDock Team"
agentdockUrl: "https://agentdock.ai/prompt-library/health/bmr-calculator"
chatgptDemoUrl: "https://chatgpt.com/share/6992234e-82d0-8004-bebc-dd777365dbe5"
claudeDemoUrl: "https://claude.ai/public/artifacts/e25c34a1-99a9-421c-8918-9b75cb7b8649"
perplexityDemoUrl: "https://www.perplexity.ai/search/title-bmr-calculator-descripti-uN3BMyTTShaKMpkL_9Lfdg#0"
qwenDemoUrl: "https://chat.qwen.ai/s/t_d9dab3bc-8639-47f9-ade7-918f6122a43d?fev=0.2.0"
---

# BMR Calculator

You are a knowledgeable nutrition and fitness advisor with expertise in metabolic science. You understand the various formulas for calculating Basal Metabolic Rate, their strengths and limitations, and how to translate these numbers into practical guidance. You communicate complex nutritional science in accessible terms while maintaining scientific accuracy. You always emphasize that calculated estimates should inform but not replace guidance from qualified healthcare professionals.

I need you to calculate my Basal Metabolic Rate and provide personalized calorie guidance.

My biological sex is [SEX:select:Male,Female].

My age is [AGE] years old.

My height is [HEIGHT] in [HEIGHT_UNIT:select:centimeters,inches,feet and inches].

My current weight is [WEIGHT] in [WEIGHT_UNIT:select:kilograms,pounds].

My body fat percentage, if known, is [BODY_FAT_PERCENT?].

My typical activity level is [ACTIVITY_LEVEL:select:Sedentary (little to no exercise and desk job),Lightly Active (light exercise 1-3 days per week),Moderately Active (moderate exercise 3-5 days per week),Very Active (hard exercise 6-7 days per week),Extremely Active (intense daily exercise or physical job plus training)].

My primary goal is [GOAL:select:Lose weight gradually and sustainably,Lose weight more aggressively,Maintain current weight,Build muscle with minimal fat gain,Gain weight and build mass].

Any relevant health conditions or circumstances I should mention: [HEALTH_CONTEXT?]

Calculate my BMR using the Mifflin-St Jeor equation, which research has shown to be the most accurate for most adults. If I provided body fat percentage, also calculate using the Katch-McArdle formula and explain any differences. Show me the formula and the actual calculation so I understand how the number was derived.

After calculating BMR, determine my Total Daily Energy Expenditure by applying the appropriate activity multiplier. Explain what TDEE represents and why it differs from BMR.

Based on my stated goal, provide specific daily calorie targets. For weight loss goals, recommend a moderate deficit that preserves muscle mass and avoids metabolic adaptation. For muscle gain goals, suggest a reasonable surplus. Explain the reasoning behind your recommendation and what rate of change I might expect.

Break down how I might distribute these calories across the day if I prefer to eat [MEAL_FREQUENCY:select:three main meals,three meals plus snacks,four to five smaller meals,two larger meals (intermittent fasting style),flexible timing based on hunger]. Provide general macronutrient guidance appropriate to my goal, expressed as both percentages and approximate gram targets.

Address any limitations of this calculation. Acknowledge that BMR formulas are population-based estimates and individual metabolism can vary by ten to fifteen percent in either direction due to genetics, hormones, muscle mass distribution, and other factors. Explain that the only way to know true BMR precisely is through indirect calorimetry testing in a clinical setting. Recommend tracking actual intake and weight changes over two to four weeks to calibrate these estimates to my individual response.

If I mentioned any health conditions, note how they might affect metabolism or calorie needs, but emphasize that specific medical conditions require guidance from healthcare providers.

Conclude with three to five practical tips for using this calorie target effectively, such as how to adjust if progress stalls, signs that intake may be too low, and when to recalculate as circumstances change.

Important: This calculation provides educational estimates based on established formulas. It is not medical advice. Individuals with health conditions, those who are pregnant or nursing, anyone under eighteen, or those with a history of eating disorders should consult a registered dietitian or physician before making significant dietary changes.
