Nutrition Calculators
Free calorie, macro, calorie deficit, and water intake calculators. Plan your diet with science-based nutrition tools.
Nutrition Calculators - Build a Diet Plan from the Numbers Up
Good nutrition starts with understanding your numbers: how many calories do you actually need, how should those calories be split across protein, carbs, and fat, how large a deficit is needed for safe fat loss, and how much water does your body require? These calculators translate your personal data into actionable dietary targets.
Four Nutrition Calculators
Calorie Calculator - Calculates your Total Daily Energy Expenditure (TDEE) using BMR × activity factor. Activity levels range from sedentary (desk job, no exercise) at 1.2× to very active (physical labour plus training) at 1.9×. Use TDEE as your maintenance baseline: eat at TDEE to maintain, below to lose, above to gain.
Calorie Deficit Calculator - Finds the daily deficit needed to lose a target weight in a target timeframe. Since ~7,700 kcal corresponds to 1 kg of body fat, a 500 kcal/day deficit yields ~0.5 kg/week of loss. Enforces a minimum intake floor (1,200 kcal for women, 1,500 for men) to prevent muscle loss.
Macro Calculator - Breaks your TDEE into protein, carbohydrate, and fat targets in both grams and calories. Supports balanced (30/40/30), high-protein (40/30/30), low-carb (30/20/50), and custom profiles. Protein is calculated first at 1.6–2.2 g/kg body weight per ISSN guidelines.
Water Intake Calculator - Recommends daily water intake based on body weight (~30–35 ml/kg), activity level (+500 ml per 30 min moderate exercise), and climate (+500–1,000 ml for hot/humid conditions).
The Four-Step Nutrition Plan
Step 1 - Find TDEE with the Calorie Calculator. Step 2 - Set a target intake with the Calorie Deficit Calculator. Step 3 - Distribute macros with the Macro Calculator. Step 4 - Set hydration target with the Water Intake Calculator. These four numbers form the complete core of any structured nutrition plan.
Note: The Calorie Calculator and BMR Calculator use the same Mifflin–St Jeor formula internally - use either as your starting point.
Frequently Asked Questions
How accurate are calorie calculators?
The Mifflin–St Jeor equation has a ±10% margin vs. measured metabolic rate. Track your actual weight change for 2–3 weeks and adjust your intake target in the Calorie Deficit Calculator accordingly if expected results don't materialise.
How much protein should I eat to build muscle?
ISSN recommends 1.6–2.2 g of protein per kg of body weight per day for muscle building. The Macro Calculator defaults to 1.8 g/kg for the muscle-building profile and distributes remaining calories across carbs and fat.
Is it safe to eat at a 500 kcal daily deficit?
A 500 kcal/day deficit producing ~0.5 kg/week of loss is generally safe for adults with BMI over 25. The Calorie Deficit Calculator enforces a minimum daily intake floor to prevent unsafe restriction.
Does coffee count toward daily water intake?
Caffeinated beverages still contribute net hydration - about 60–70% of their volume counts. The Water Intake Calculator recommends pure water targets; caffeinated drinks can partially contribute but should not replace the calculated water goal.