MrKeepFit — Free Health & Fitness Tools, Calculators & Guides
Free · No Sign-Up · Evidence-Based

Free Health &
Fitness Tools
That Actually Work

Calculators, timers and guides built on real science. Calculate macros, check your BMI, time your HIIT and find healthy ingredient swaps — all free, right now.

Try a tool instantly →

29
Calculators
100%
Evidence-Based
100%
Free
0
Sign-Ups
Age
Gender
Weight (kg)
Height (cm)
Activity Level
Goal
—
Calories
—
Protein
—
Carbs
—
Fat
Open full Macro Calculator with custom ratios →
Body Metrics

Composition &
Shape Analysis

Understand your physical baseline with tools for BMI, body fat, lean mass, and more.

📐
BMI & Body Fat
Calculate BMI and estimate body fat % using the Navy method.
Calculate Now →
⚖️
Ideal Weight
Find your healthy weight range based on height and frame.
Calculate Now →
💪
Lean Body Mass
Estimate your muscle mass and total body composition.
Calculate Now →
📏
Waist-to-Hip Ratio
Assess health risks by analyzing body fat distribution.
Calculate Now →
🦴
Frame Size
Determine your bone structure to refine weight goals.
Calculate Now →
👤
Body Surface Area
Calculate BSA for clinical and performance metrics.
Calculate Now →
Nutrition & Diet

Fueling &
Metabolism

Optimize your intake with macro calculators, metabolic trackers, and nutrient tools.

🧮
Macro Calculator
Personalised targets for protein, carbs, and fat.
Calculate Now →
🔥
BMR Calculator
Find your Basal Metabolic Rate—the calories you burn at rest.
Calculate Now →
⚡
TDEE Calculator
Total daily energy expenditure based on activity level.
Calculate Now →
🥩
Protein Calculator
Calculate optimal protein intake for muscle growth.
Calculate Now →
💧
Water Intake
Find your ideal daily hydration target based on weight.
Calculate Now →
☕
Caffeine Tool
Calculate safe caffeine limits and supplement timing.
Calculate Now →
💊
Creatine Dosage
Optimal loading and maintenance doses for creatine.
Calculate Now →
🔄
Ingredient Swaps
Find healthy alternatives for any cooking ingredient.
Calculate Now →
Training

Performance &
Athletics

Track your strength, speed, and recovery with professional training tools.

⏱
Workout Timer
Interval timer for Tabata, HIIT, EMOM, and boxing.
Start Timer →
🏋️
1RM Calculator
Estimate your maximum lift capacity safely and accurately.
Calculate Now →
🏃
Running Pace
Calculate speed, time, or distance for your next run.
Calculate Now →
❤️
Heart Rate Zones
Identify aerobic and anaerobic training zones.
Calculate Now →
🏆
Wilks Calculator
Compare strength across body weights (Powerlifting).
Calculate Now →
🥇
Sinclair Tool
Compare strength across body weights (Weightlifting).
Calculate Now →
Weight Management

Progress &
Tracking

Data-driven tools to help you manage weight loss or gain with precision.

📉
Calorie Deficit
Calculate the exact deficit needed for your goal weight.
Calculate Now →
📊
Weight Loss %
Track your total weight loss as a percentage of start weight.
Calculate Now →
📅
Target Date Tool
Estimate when you’ll reach your goal weight.
Calculate Now →
🍽️
Macro Ratio Tool
Customise your protein, carb, and fat distribution.
Calculate Now →
Health & Lifestyle

Daily
Wellness

Manage your health beyond the gym with lifestyle-focused utility tools.

🌙
Sleep Calculator
Find the best time to wake up or go to bed for recovery.
Calculate Now →
🌸
Ovulation Tool
Identify your fertile window and track your cycle.
Calculate Now →
👶
Due Date Tool
Estimate your due date based on last period or conception.
Calculate Now →
🚬
Smoking Cost
Calculate money saved and health gained by quitting.
Calculate Now →
🍺
BAC Calculator
Estimate Blood Alcohol Content based on intake.
Calculate Now →
Simple Process

How to Use
Our Tools

01
🎯
Choose Your Tool
Select from our free calculators and timers. Each is purpose-built for a specific fitness or nutrition goal.
02
✏️
Enter Your Details
Input your measurements or search term. No account, no email, no personal data stored — ever.
03
⚡
Get Instant Results
Results calculated instantly in your browser using validated scientific formulas. No waiting.
04
📈
Apply & Progress
Use your results alongside our evidence-based tools to build a plan that fits your life.
Why MrKeepFit

Built for Real
Results

There’s no shortage of fitness content online — but most of it is either too vague to be useful, or hidden behind paywalls and email sign-ups.

Every tool, calculator and resource on MrKeepFit is free, science-backed and built for practical daily use — whether you’re tracking macros, checking your BMI, timing a workout or swapping an ingredient.

Learn About Our Approach →
🔬
Evidence-Based Formulas
Our calculators use validated scientific formulas — Mifflin-St Jeor for TDEE, U.S. Navy Method for body fat, WHO standards for BMI.
🔒
No Data Stored
All calculations happen locally in your browser. We never store, sell or share your personal measurements or health data.
💸
Completely Free — Always
Every tool on MrKeepFit is free to use with no account required, no premium tiers and no paywalls. That’s a promise.
📱
Works on Any Device
All tools are fully responsive. Use the workout timer in the gym directly from your phone — works offline too.
⚡
Instant Results
Results are calculated immediately — no loading screens, no server requests, no waiting around.

The Ultimate Fitness Tool Hub

MrKeepFit is a dedicated platform providing free, evidence-based health and fitness tools. We believe that tracking your data shouldn’t be complicated or expensive. That’s why we’ve built a suite of 29 calculators and timers to help you achieve your goals with precision.

Our tools use validated scientific formulas, including the Mifflin-St Jeor equation for metabolic rates and the U.S. Navy Method for body composition analysis.

Our Core Tool Categories

  • Body Metrics: Get accurate estimates of body fat, lean mass, and ideal weight.
  • Nutrition: Calculate macros, BMR, and hydration needs based on your unique biology.
  • Training: Use 1RM calculators and interval timers to optimize your performance.
  • Weight Loss: Track your deficit and progress with data-driven management tools.

Why Use Scientific Calculators?

Generic advice often fails because it doesn’t account for individual variance. By using tools like our Macro Calculator or TDEE Tracker, you get personalized targets that adapt to your body type, activity level, and goals.

Whether you’re an athlete looking to optimize performance using the Wilks Coefficient or a beginner starting a weight loss journey, our tools provide the roadmap for success.

Completely Free & Private

Every tool on MrKeepFit is 100% free, forever. We don’t require sign-ups, we don’t ask for your email to show results, and all calculations happen locally in your browser. Your data stays yours.