30 science-backed calculators reviewed by certified professionals. Get accurate results in seconds — no sign-up required.
Calculate your daily calorie needs based on age, gender, weight, height, and activity level using the Mifflin-St Jeor equation. Free and accurate.
Calculate your Body Mass Index (BMI) and see where you fall on the WHO health range chart. Supports both metric and imperial units instantly.
Calculate your Total Daily Energy Expenditure (TDEE) with precision. Factor in BMR, activity level, and exercise to find your true calorie burn.
Calculate your ideal macronutrient split for weight loss, muscle gain, or maintenance. Get personalized protein, carb, and fat targets in grams.
Predict your ovulation date and fertile window based on your cycle length. Track your most fertile days for conception or natural family planning.
Build a monthly budget using the 50/30/20 rule. Allocate your income to needs, wants, and savings with a personalized budget breakdown instantly.
Calculate your daily calorie needs based on age, gender, weight, height, and activity level using the Mifflin-St Jeor equation. Free and accurate.
Calculate your Total Daily Energy Expenditure (TDEE) with precision. Factor in BMR, activity level, and exercise to find your true calorie burn.
Calculate your ideal macronutrient split for weight loss, muscle gain, or maintenance. Get personalized protein, carb, and fat targets in grams.
Find your optimal daily protein intake based on body weight, activity level, and fitness goals. Uses ISSN and WHO evidence-based guidelines.
Calculate your Body Mass Index (BMI) and see where you fall on the WHO health range chart. Supports both metric and imperial units instantly.
Estimate your body fat percentage using the U.S. Navy method with neck, waist, and hip measurements. See healthy body fat ranges by age and sex.
Calculate how much water you should drink daily based on your weight, activity level, and climate. Science-backed hydration recommendations.
Calculate your ideal calorie deficit for safe, sustainable weight loss. See how long it takes to reach your goal weight with a personalized plan.
Calculate your intermittent fasting schedule with custom eating windows. Choose from 16:8, 18:6, 20:4, or OMAD protocols with calorie targets.
Split your daily calories across meals and snacks with a custom meal plan calculator. Choose 3-6 meals per day with balanced macro distribution.
Calculate your one rep max for any lift using the Epley, Brzycki, or Lombardi formulas. Get accurate strength estimates from your working sets.
Calculate your running pace, finish time, or distance for any race. Supports 5K, 10K, half marathon, and marathon with split predictions.
Calculate calories burned during 100+ exercises including running, walking, cycling, swimming, and strength training. Based on MET values.
Convert your daily step count into calories burned. Factor in your weight, pace, and terrain for an accurate walking calorie burn estimate.
Calculate how many rest days you need per week based on training intensity, volume, experience, and sleep quality. Prevent overtraining now.
Calculate your five heart rate training zones based on max heart rate or the Karvonen formula. Optimize fat burn, endurance, and performance.
Estimate your VO2 max using the Cooper test, Rockport walk test, or running performance. See your cardiorespiratory fitness level and percentile.
Calculate your lean body mass (fat-free mass) using the Boer formula. Essential for setting protein targets and tracking body recomposition.
Track your pregnancy weight gain by trimester against IOM guidelines. See if you are on track for a healthy pregnancy based on your pre-pregnancy BMI.
Calculate your daily calorie needs postpartum for safe recovery and gradual weight loss. Accounts for breastfeeding status and activity level.
Predict your ovulation date and fertile window based on your cycle length. Track your most fertile days for conception or natural family planning.
Predict your next period date and cycle length based on your menstrual history. Track cycle regularity and identify patterns over time.
Calculate age-appropriate baby food portion sizes from 4-24 months. Based on AAP and WHO complementary feeding guidelines for healthy infants.
Calculate your daily calorie needs while breastfeeding based on feeding frequency, baby's age, and your weight loss goals. Stay nourished safely.
Calculate your ideal weight range using Devine, Robinson, Miller, and Hamwi formulas. See healthy weight ranges customized by height and frame size.
Build a monthly budget using the 50/30/20 rule. Allocate your income to needs, wants, and savings with a personalized budget breakdown instantly.
Calculate how much to save monthly to reach your financial goal by your target date. Factor in interest and existing savings for an exact plan.
Compare debt snowball vs avalanche strategies. See your payoff date, total interest paid, and monthly payment plan for each method side by side.
Calculate a realistic monthly grocery budget based on household size, diet type, and USDA food plan tiers. Plan your food spending with confidence.
Calculate the cost per meal for your meal prep recipes. Compare meal prepping costs vs eating out and see your monthly savings potential.
Learn what a healthy BMI range is, how BMI is calculated, its limitations for athletes and older adults, and better alternatives for measuring health.
Learn exactly how to calculate your calorie deficit for safe, sustainable weight loss. Step-by-step guide with TDEE, BMR, and real-world examples.
Compare the best macronutrient ratios for fat loss and muscle gain. Science-backed protein, carb, and fat splits with practical meal examples.
Every formula and article on CalcNest is reviewed by certified professionals to ensure accuracy and reliability.
Sarah Mitchell
RD, MS Nutrition
James Okafor
ACSM-CPT, CSCS, MS Exercise Science
CalcNest offers a comprehensive suite of 30 free online calculators designed to help you make informed decisions about your health and finances. Our nutrition calculators include tools for daily calorie needs, macronutrient ratios, BMI, body fat percentage, protein intake, water requirements, and intermittent fasting schedules — all powered by peer-reviewed formulas like the Mifflin-St Jeor equation and USDA dietary guidelines. For fitness enthusiasts, we provide one-rep max estimators, running pace calculators, heart rate zone finders, VO2 max assessments, and calories burned trackers based on the Compendium of Physical Activities. Our women's health section features pregnancy weight gain trackers, ovulation predictors, period trackers, breastfeeding calorie calculators, and baby food portion guides aligned with AAP and WHO recommendations. On the financial side, CalcNest helps you build monthly budgets using the 50/30/20 rule, plan savings goals with compound interest projections, compare debt payoff strategies (snowball vs. avalanche), estimate grocery budgets using USDA food plan tiers, and calculate meal prep savings. Every calculator is reviewed by our expert editorial team — including a Registered Dietitian and an ACSM Certified Personal Trainer — to ensure accuracy, transparency, and alignment with current evidence-based guidelines.