What this Macro Calculator does
This English-language macro calculator uses the Mifflin-St Jeor equation to estimate your Basal Metabolic Rate (BMR), then applies an activity multiplier to find your Total Daily Energy Expenditure (TDEE). From there it splits your calories into protein, carbohydrates, and fat targets tailored to your goal — cut, maintain, or bulk. Unlike popular fitness sites that harvest your email before showing results, this tool is 100% client-side — your data never leaves your browser. No uploads, no tracking, no server logs. All three goal scenarios are displayed side by side so you can compare the trade-offs without re-entering your stats three times. The IRS uses BMI bracket tables only as a flag for further screening, never as a sole diagnostic — similarly, treat these macros as a starting point, not a medical prescription. For a broader picture of your energy balance, pair this with our [TDEE calculator](/en/tdee-calculator/) or check your body composition with the [BMI calculator](/en/bmi-calculator/).
Features
- Mifflin-St Jeor BMR. Uses the clinically validated Mifflin-St Jeor formula — the one most registered dietitians recommend over older Harris-Benedict equations.
- Three-goal comparison. Cut, maintain, and bulk results appear simultaneously so you can see exactly how calorie and macro targets shift across your options.
- Activity-adjusted TDEE. Five activity levels from sedentary to very active scale your base metabolic rate to reflect real daily energy output, not just resting calories.
- Goal-tailored macro splits. Each goal applies a different protein-to-carb-to-fat ratio. A cut prioritizes higher protein to preserve muscle; a bulk redistributes toward carbs for training fuel.
- Zero data collection. All math runs in your browser using the Web Crypto API-grade client-side architecture — no form submission, no server, no account required.
- Imperial and metric support. Enter your weight in pounds or kilograms and height in feet/inches or centimeters — the calculator handles the conversion before computing your targets.
How to use the Macro Calculator
Fill in your stats, pick your activity level and goal, then hit Calculate. Results appear instantly — no page reload needed.
- Enter your biometrics. Input your age, biological sex, weight, and height. Use the unit toggle to switch between
lbs/ftandkg/cmif needed. - Select your activity level. Choose the tier that best describes your week — from sedentary (desk job, no gym) up to very active (physical labor or twice-daily training).
- Choose a primary goal. Select cut, maintain, or bulk. The calculator will display all three side by side so you can see how the numbers change.
- Review your macros. Read your daily calorie target and the gram breakdown for protein, carbohydrates, and fat. Use the Copy button to grab the numbers for your tracking app.
- Adjust and iterate. If the targets feel off after a week, tweak your activity level or adjust the calorie surplus/deficit before changing the macro split itself.
Common use cases
- Fat loss planning. Someone in San Francisco starting a cut can use the macro calculator for weight loss to set a moderate 300–500 kcal deficit and verify they're eating enough protein to minimize muscle loss.
- Muscle-gain phases. Lifters in a bulk cycle use the calculator to find the calorie surplus that supports hypertrophy without excessive fat gain, then track grams of each macro daily.
- Maintenance and recomposition. Athletes who want to hold weight while slowly shifting body composition use the maintain target as a baseline and adjust protein upward incrementally.
- Comparing tracking apps. Users who distrust the macro calculator MyFitnessPal sets by default can verify those numbers here independently — this free macronutrient calculator uses published equations, not a black-box algorithm.
- Nutrition coaching prep. Personal trainers run multiple client profiles quickly before a session, using the side-by-side goal view to show clients the trade-offs between cutting and maintaining at a glance.
Frequently asked questions
Is my data stored or sent to a server?
No. Every calculation runs locally in your browser. Nothing is transmitted, logged, or stored. The architecture follows the same client-side isolation model described in the NIST SP 800-63B digital identity guidelines — your personal stats are simply never in transit.
What's the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the calories your body burns at complete rest — essentially the energy cost of staying alive. TDEE (Total Daily Energy Expenditure) multiplies BMR by an activity factor to reflect how much you actually burn in a day. Your macro targets are based on TDEE, not BMR.
How accurate is the Mifflin-St Jeor equation?
It's the most widely validated formula for estimating resting metabolic rate in healthy adults and is preferred over older methods in most clinical nutrition literature. That said, individual metabolism varies, so treat the output as a calibrated starting point and adjust based on real-world results over two to four weeks.
How does this compare to the macro calculator in MyFitnessPal?
The mfp macro calculator uses a similar TDEE approach but applies fixed percentage splits (by default 50% carbs, 30% fat, 20% protein) that don't adjust for goal. This calculator applies goal-specific splits — higher protein for a cut, higher carb allocation for a bulk — which better matches current sports nutrition guidance.
How do macros work for fat loss specifically?
Weight loss calculator macros typically set a calorie deficit of 300–500 kcal below TDEE, then prioritize protein (1.6–2.2 g per kg of bodyweight) to preserve lean mass while the deficit drives fat loss. Carbs and fat fill the remaining calories based on personal preference and training demands.
Do I need to count macros every day forever?
Counting macros is most useful during an active cut or bulk phase to build intuition around portion sizes and food composition. Once you internalize what your targets look and feel like on a plate, many people shift to looser tracking. Apps that track macros are helpful for accountability early on, but the goal is to eventually eat by feel.