Macro Calculator Online
Split your daily calories into protein, carb, and fat grams by ratio, right in your browser. A general estimate, not medical advice.
The Macro Calculator runs entirely in your browser. The calories and percentages you enter never leave your device and nothing is uploaded to ArrayKit.
Open the Protein Calculator
About Macro Calculator
Macro Calculator takes your daily calorie target and a protein/carb/fat ratio and converts it straight into grams you can track. Pick a built-in preset — balanced 30/40/30, keto 25/5/70, or high-protein 40/30/30 — or dial in a fully custom split for IIFYM-style flexible dieting. Protein and carbs are converted at 4 kcal per gram and fat at 9 kcal per gram, the standard energy values used by most nutrition apps and food labels. If your three percentages do not add up to 100%, the tool flags it so you can adjust before you commit to a plan. It is built for lifters, endurance athletes, and anyone following a structured eating plan who wants a quick gram breakdown without opening a spreadsheet. This is a general estimate using a standard formula, not medical advice, and every calculation runs locally in your browser.
Features
- Three built-in presets: balanced, keto, and high-protein ratios
- Fully custom protein/carb/fat percentage split for IIFYM tracking
- Converts percentages to grams using 4 kcal/g protein and carbs, 9 kcal/g fat
- Warns when your three percentages do not sum to 100%
- Copy a plain-text summary of calories, ratio, and grams in one click
- Works with any daily calorie target, including totals from a TDEE calculator
- Instant recalculation as you adjust calories or percentages
- Runs entirely in your browser — no diet data leaves your device
How to use the Macro Calculator
- Enter your daily calorie target
- Choose a preset ratio or select Custom
- Fine-tune the protein, carb, and fat percentages if needed
- Read off protein, carb, and fat grams, or copy the summary
Example
Input
2000 cal, 30/40/30
Output
P 150g · C 200g · F 67g
2000 calories split at a balanced 30% protein / 40% carb / 30% fat ratio.
Common errors & troubleshooting
- Grams look too low or too high compared to a nutrition app. — Confirm your daily calorie target matches what the other app uses — the Macro Calculator only converts the ratio you enter, it does not estimate your calorie needs.
- The tool warns that percentages do not add up to 100%. — Check each of the three fields — protein, carbs, and fat should sum to 100. A common mistake is leaving a preset partly edited after switching to Custom.
- Fat grams seem small on a high-fat plan like keto. — Fat is calculated at 9 kcal per gram, not 4, so the same percentage of calories yields fewer grams than protein or carbs at the same percentage.
Frequently asked questions
- What is a Macro Calculator?
- It is a tool that converts a daily calorie target and a protein/carb/fat percentage split into grams of each macronutrient, using 4 kcal/g for protein and carbs and 9 kcal/g for fat.
- How does the Macro Calculator handle keto ratios?
- Choose the Keto preset (25% protein, 5% carbs, 70% fat) or enter your own low-carb split, and the tool converts it into daily protein, carb, and fat grams using the standard kcal-per-gram values.
- Do my macro percentages need to add up to 100%?
- They should for the grams to represent your full calorie target. The Macro Calculator shows a warning if your protein, carb, and fat percentages do not sum to 100%, so you can spot the mistake before tracking against it.
- Where should my daily calorie number come from?
- Any source works — a target from a doctor, a TDEE calculator, or a coach's recommendation. Enter that number into the Macro Calculator and it handles the protein/carb/fat conversion.
- Is the Macro Calculator medical advice?
- No. It is a general estimate using a standard formula for converting a calorie and ratio into grams, not medical or nutrition advice. Talk to a registered dietitian or doctor before making significant diet changes.
- Does the Macro Calculator store or upload my diet information?
- No. Every calculation happens locally in your browser. The calories and percentages you enter are not uploaded to ArrayKit or stored anywhere.
Related tools
- Calorie Calculator — Estimate daily calories to maintain, lose or gain weight from your stats.
- TDEE Calculator — Estimate total daily energy expenditure from BMR and activity level.
- Protein Calculator — Estimate your daily protein needs from weight and activity level.
- Carbohydrate Calculator — Estimate daily carbohydrate grams from your calories and diet split.
- Fat Intake Calculator — Estimate daily dietary fat grams from your calories and target percentage.
- BMR Calculator — Estimate your basal metabolic rate — the calories your body burns at rest.
All ArrayKit tools