Free Health Tools
BMI Calculator
Instantly calculate your BMI and understand what the result means — and what it doesn’t — for your health.
Interpreting BMI
Understand Your BMI - And What It Means For Your Health
Fettle turns nutrition science into a practical system that adapts week by week - helping you eat better, stay consistent, and make progress without overthinking or obsessing over every meal.
Instead of rigid plans or constant manual tracking, Fettle guides decisions upfront and adjusts as your body, habits, and goals change over time.
Is my BMI Good or Bad - and what should i do next?
Why does BMI sometimes give 'Wrong' results?
How do i turn my BMI into a daily calories & protein target:
Daily Nutrition Targets
Calculating your Personal Daily Calorie & Protein Targets
Using your height, weight, age, and activity level, we estimate your Total Daily Energy Expenditure (TDEE) the calories your body needs each day.
Protein Calculator Daily Protein Targets
Protein needs vary by body weight, goal and activity - not one-size-fits-all-rules.
This is a LOT to calculate - and it changes over time depending on your goal.
Fettle updates these targets automatically, based on your weight, activity, goals, and weekly progress.
Why Thousands Trust Fettle
Doing your own calculations is the #1 reason people fail.
Fettle updates them automatically - every single week.
Science-Backed Calculations
Most calorie calculators use outdated formulas or oversimplified numbers.
Fettle uses a clinically validated method designed by a registered nutritionist - the same approach used by professionals working with athletes and weight-loss patients.
Adjusts for body fat %, not just height and weight
Calculate minimum safe fats, proteins and carbs
Re-checks metabolic data every week
Weekly Personalisation
Your body changes - your calories should too.
Every 7 days, Fettle analyses your check-in data (weight, waist, hips, activity) and automatically adjusts your calories and macro targets. No guesswork. No manual maths. No confusion.
Accounts for plateaus and metabolic slowdown.
Prevents overeating or under-eating.
Designed for long-term sustainable results.
Real-Life Usability
You don't live inside a spreadsheet - and your nutrition plan shouldn't feel like one.
Fettle gives you simple meal plans, quick swaps, realistic recipes, and a shopping list that fits your actual lifestyle.
Recipes based on your taste preferences.
Amazon Fresh Integration (Others coming soon).
Works whether you cook daily or rely on quick meals.
Why People Love Fettle
What fits your target
Meals are matched to your targets — not the other way around.
Fettle helps you choose foods and portions that fit your goals and preferences, without rigid rules or food anxiety.
How to plan for real life
From meal ideas to shopping lists, Fettle helps you plan in a way that works outside the app.
So staying on track feels practical, flexible, and sustainable — even on busy weeks.
How much to eat
Fettle calculates your calorie and macro targets using evidence-based formulas — then updates them as your body, activity, and goals change.
You start with clarity, not guesswork.
Quick answers
How Accurate is the Calorie Calculation?
Fettle's calorie targets are estimates, not absolute numbers - and that's intentional. We use clinically validated equations to calculate your starting energy needs, then refine them over time using real-world progress trends, not single data points. This approach is more reliable than a one-off calculation because your calorie needs change as your body and habits change. No calorie calculation is perfectly precise, but adaptive systems are consistently more accurate than static targets.
