Macro Calculator
Calculate your optimal daily macro split and calorie intake instantly. Custom tailoring for weight loss, muscle gain, and keto diets. 100% client-side, interactive, and private.
What is This Tool
"Just eat in a deficit" is the most useless advice in fitness until someone tells you what that actually means in grams. A macro calculator takes your height, weight, age, and how much you actually move during the day, and turns it into three real numbers: protein, carbs, and fat, measured in grams, not vibes. It's the same math a coach would scribble on the back of a gym receipt, except this one updates the second you change a number.
What makes this one different is that it doesn't stop at a single calorie total. You get to pick the formula behind the science (Mifflin-St Jeor if you want the modern standard, Harris-Benedict if that's what your program is built around), then watch your total calories split into a live protein-carb-fat ring that redraws itself as you drag things around. No spreadsheets, no rounding errors, no "close enough."
How to Use
- Pick Imperial or Metric, then fill in your gender, age, height, and weight. That's the raw data the whole calculation is built on.
- Choose your calorie formula and activity level so the tool knows how many calories your body burns just existing, plus how much your training adds on top.
- Set your goal (Cut, Maintain, or Bulk) and, if you're cutting or bulking, drag the range slider to control exactly how aggressive the deficit or surplus is.
- Pick a diet style like Balanced, Low Carb, or Keto, or hit Custom and drag your own protein, carb, and fat sliders until the donut chart matches the plan you actually want to follow.
Key Features
- Two proven calorie formulas built in, Mifflin-St Jeor by default and Harris-Benedict for anyone whose coach or program calls for it.
- Goal presets with real adjustable ranges, so a "cut" isn't a fixed 15% for everyone, you can dial it between 10% and 20% based on how fast you want results.
- Four ways to split your macros: Balanced, Low Carb, Keto, or fully custom sliders that stay locked to 100% no matter how you drag them.
- A live SVG donut chart that redraws in real time as you change any input, with your daily calorie target shown right in the center.
- Everything runs in your browser. There's no server call, no account, and no record of your body stats anywhere but your own device.
Common Use Cases
- Cutting for a wedding, a photoshoot, or just to see your abs again, and needing exact numbers instead of guessing at portion sizes.
- Bulking on purpose instead of just "eating more" and ending up with more fat gain than muscle to show for it.
- Running a Keto or low-carb plan and needing your carb ceiling locked in precisely instead of estimating grams by eye.
- Coaches and trainers who need a fast, accurate starting point for a new client before fine-tuning based on real-world progress.
- Recomping, where your weight barely moves but you want your protein and fat ratios dialed in to actually change your body composition.
Frequently Asked Questions
Is this Macro Calculator free to use?
Yes, completely free, with no sign-up and no cap on how many times you recalculate. Run it every time your weight or activity level changes.
What's the difference between BMR and TDEE?
BMR is the calories your body burns just staying alive, no movement included. TDEE takes that number and adds in your activity level, giving you the actual calorie total your day-to-day life burns.
Which diet style should I choose?
Balanced works for most people who just want a sustainable ratio. Low Carb suits people who feel better with fewer carbs but still want solid protein. Keto is for a strict low-carb, high-fat approach. If none of those fit, Custom lets you build your own split from scratch.
Does the tool account for how active I am?
Yes, the Activity Level dropdown covers everything from a desk job with no exercise to two-a-day training, and it directly changes your TDEE and calorie target.
Is my data saved anywhere?
No. Every calculation happens locally in your browser using JavaScript. Nothing about your age, weight, or goals is sent to a server or stored anywhere.
Advanced Tips
- Recalculate every four to six weeks, or any time your weight shifts by more than a few pounds, since your BMR changes along with your body.
- Even on Keto, don't drag your protein slider too low if you're lifting weights. Muscle needs protein regardless of how few carbs you're eating.
- If you're prepping for a specific event, use the Custom sliders to fine-tune your split week by week instead of sticking with one preset the whole time.
- Weigh yourself at the same time of day, ideally right after waking up, before you plug your weight into the calculator for the most consistent results.