Every tool here pulls its multipliers from primary sources. The numbers you get are the same numbers you would get from reading a meta-analysis, only faster. Use them as a starting point, not as a substitute for working with a clinician when one is appropriate.
Protein Calculator
How much protein per day for muscle gain, fat loss, endurance, or general health. Built on the 2018 BJSM meta-analysis of 49 RCTs (Morton et al.) and the ISSN position stand on protein and exercise.
Open calculator →BMI & Waist-to-Height Ratio
WHO BMI categories paired with the Ashwell 2012 waist-to-height ratio, which outperforms BMI for cardiometabolic risk. Catches the muscular-but-flagged-overweight false positive and the normal-BMI-with-hidden-visceral-fat case.
Open calculator →TDEE & Calorie Calculator
Daily calorie needs via Mifflin-St Jeor (validated by Frankenfield et al. 2005), with an optional Katch-McArdle path when body fat percent is known. Returns BMR, TDEE, and goal-aware cut, maintain, and bulk targets.
Open calculator →Macro Calculator
Five goal modes: aggressive cut, moderate cut, maintain, lean bulk, standard bulk. Each sets the deficit or surplus from a published band and moves protein with it, anchored to Morton et al. 2018 (BJSM, 49 RCTs, n=1,863), plus the projected weekly rate.
Open calculator →Body Fat Calculator
US Navy circumference method (Hodgdon & Beckett 1984, r=0.90 vs hydrostatic weighing) with explicit accuracy bands. Optional 3-site Jackson-Pollock skinfold mode for caliper users.
Open calculator →1 Rep Max Calculator
Strength estimator averaging Epley, Brzycki, and Lombardi formulas. Shows the spread, applies rep-based accuracy bands, and includes a percentage table for hypertrophy, strength, and power.
Open calculator →Heart Rate Zone and Max Heart Rate Calculator
Max heart rate from your age by Tanaka 2001 (208 minus 0.7 times age, pooled from 18,712 subjects), Fox 1971 and Nes 2013, shown side by side. Then all 5 training zones by percent of max and by the Karvonen heart rate reserve method.
Open calculator →Free AI Workout Plan Generator
Get a personalized workout plan from five answers: goal, experience, days, equipment, and session time. Split and volume follow Schoenfeld et al. 2016 and 2017. Copy a link to the plan or print it as a PDF. Free, runs in your browser, no signup.
Open generator →Deck of Cards Workout Generator
Pick a workout and how long you have, then flip one card at a time. Each card shows one exercise and the reps, with a picture and a form tip for every move. Free, runs in your browser, no signup.
Open generator →7 Minute Workout
A free follow-along timer: a 1-minute warm-up, a 5-minute circuit and a 1-minute stretch at four levels, with a picture and a form tip for every move. It beeps, an AI coach from the FitCraft app calls out each move, and it keeps your screen awake. Free, runs in your browser, no signup.
Open timer →Calisthenics Workout Plan
A free weekly calisthenics plan at four levels for 3, 4 or 5 days a week, with or without a pull-up bar. Push, pull, legs and core ladders show where you start and when to move up, and a guided session runs each workout.
Build my plan →At-Home Fitness Test
Take five guided tests at home: a 3-minute step test, sit and reach, push-ups, a plank and a wall sit. Each is scored for your age and sex where published norms exist, with a retest date and your change saved on this device.
Start the test →Beep Test Player
Run the 20 m beep test with exact audio for all 21 levels, a triple beep at each new level and a big level and shuttle display. Tap I'm out to save your score, see an estimated VO2 max and compare it for your age.
Open the beep test →75 Soft Challenge Tracker
A free 75 Soft tracker: tap off a 45-minute workout, 3 liters (101 oz) of water, 10 pages and eating well each day. It keeps your streak, XP and badges on your device, allows one recovery day a week and prints a one-page 75-day checklist.
Open the tracker →30 Day Workout Challenge
Pick full body, abs, squats, plank or push-ups and follow one short guided session a day for 30 days. Every day shows its length in minutes, with rest days, XP, badges and a streak kept on your device. Free, no signup.
Start the challenge →12 Days of Christmas Workout
Do the song as a workout: each day adds a new move, then counts back down to one. Tap Done after every set and the page keeps count, with a warm-up, a stretch, four levels, XP and a bell for every finished day.
Start the workout →Interval Timer
A free HIIT interval timer: one-minute rounds of work and rest at four levels, from 30 seconds on and 30 off to 50 on and 10 off, with a picture and a form tip for every move. An AI coach from the FitCraft app calls out each move. Free, runs in your browser, no signup.
Open timer →Tabata Timer
A free Tabata timer: 8 rounds of 20 seconds of work and 10 seconds of rest, one to four Tabatas, with two moves to alternate at each level and a picture and a form tip for every move. Free, runs in your browser, no signup.
Open timer →EMOM Timer
A free EMOM timer: a set number of reps at the start of every minute, then rest until the next one, for 10 to 20 minutes. Tap Finished my reps when your reps are done to turn the time left into bonus XP. Free, runs in your browser, no signup.
Open timer →BMR Calculator
Your resting burn from three published equations at once: Mifflin-St Jeor 1990, the revised Harris-Benedict of Roza and Shizgal 1984, and Katch-McArdle when body fat is known. Defaults to Mifflin-St Jeor on the evidence of the Frankenfield et al. 2005 systematic review, and shows the accuracy band.
Open calculator →Body Recomposition Calculator
Find out whether losing fat and building muscle at once is realistic for you, then get the calorie, protein and training numbers that decide it. Feasibility follows the Barakat et al. 2020 review in the Strength and Conditioning Journal; calories use Mifflin-St Jeor.
Open calculator →Calories Burned Calculator
Calories burned for 12 activities: walking and running by pace, treadmill incline, steps, cycling, swimming, stairs, jump rope, circuits, lifting and yoga. MET values from the 2024 Adult Compendium of Physical Activities (Herrmann et al. 2024), with gross and net calories.
Open calculator →Steps to Miles Calculator
Convert any step count into miles and kilometers using a step length estimated from your height and sex, checked against the normative gait database in Mobbs et al. 2025 (Sensors, 313 adults). Separate running step lengths and a calorie estimate included.
Open calculator →FFMI Calculator
Fat-free mass index, height-normalized FFMI and lean body mass, with or without a body fat number. Normalization follows Kouri et al. 1995, the Boer 1984 formula fills in a blank body fat field, and every reference band comes from a published study.
Open calculator →Water Intake Calculator
How much water to drink each day, from the IOM 2005 and EFSA 2010 Adequate Intakes adjusted for body weight, heat and altitude with the water-turnover equation of Yamada et al. 2022 (Science, 5,604 people), plus a sweat-based exercise add-on.
Open calculator →Weight Loss Percentage Calculator
The share of your starting weight you have lost, your next 5, 10, 15 or 20% milestone, goal progress and weekly pace. Milestones follow the 2013 AHA/ACC/TOS obesity guideline (Jensen et al. 2014), with STEP 1 and SURMOUNT-1 benchmarks for GLP-1 users.
Open calculator →VO2 Max Calculator
Estimate VO2 max four ways: resting heart rate (Uth et al. 2004), the Rockport 1-mile walk (Kline et al. 1987), a 1.5-mile run or the Cooper 12-minute run. Each result gets a likely error range and a percentile from the FRIEND registry (Kaminsky et al. 2015).
Open calculator →Cooper Test Calculator
Turn your 12-minute run distance into VO2 max with Cooper's 1968 equation, rated against Cooper Clinic percentiles for age and sex (Kaminsky et al. 2015). A built-in 12-minute timer counts your 400 m laps and fills in the distance for you.
Open calculator →Max Heart Rate Calculator
Your maximum heart rate from age and sex by eight published formulas side by side, with the Tanaka et al. 2001 estimate from 18,712 people as the recommended pick, a likely range from the 11 bpm standard error, and a safe field test.
Open calculator →Army Body Fat Calculator
Checks the current Army body composition standard, a waist-to-height ratio under 0.55 set by Army Directive 2026-13 in July 2026, with the Army's own rounding rules from EXORD 182-26 Annex A, and shows the largest waist that passes at your height.
Open calculator →Waist to Hip Ratio Calculator
Divide your waist by your hips and compare the result with the cut-offs in the WHO 2008 expert consultation: 0.85 for women, 0.90 for men. Shows the waist at which your hips reach the line, the WHO waist lines and lower example values for Asian adults.
Open calculator →Waist to Height Ratio Calculator
Your waist to height ratio in the NICE NG246 bands (0.4 to 0.49 healthy, 0.5 to 0.59 increased, 0.6 or more high), the waist that keeps you under half your height, and a body fat estimate from the relative fat mass equation of Woolcott and Bergman 2018.
Open calculator →Walking Calorie Calculator
Calories burned walking by pace and minutes, miles or steps, with hills, grass, soft sand and a backpack. Level walking uses 2024 Adult Compendium codes (Herrmann et al. 2024), shown beside the ACSM walking equation, with calories per mile and above resting.
Open calculator →Treadmill Calorie Calculator
Treadmill calories from belt speed, incline and minutes, walking or running, with the cost of holding or leaning on the handrails (Berling et al. 2006, Hofmann et al. 2014). Uses the ACSM equations and 2024 Compendium treadmill codes, with a console-style comparison.
Open calculator →Lean Body Mass Calculator
Lean body mass from your sex, height and weight with the Boer, James, Hume and Janmahasatian formulas side by side, or directly from a body fat percentage. Accuracy figures come from a DXA test of 1,558 adults (Puri and Blake 2022).
Open calculator →Weight Loss Date Calculator
When you will reach your goal weight from a daily calorie deficit or weekly pace, with the classic 3,500 calorie rule next to falling energy needs (Hall et al. 2011, Lancet), or the pace and deficit a target date needs.
Open calculator →Ideal Weight Calculator
The Devine, Robinson, Miller and Hamwi ideal body weight formulas side by side for your sex and height, shown as a range next to the BMI healthy range. Accuracy notes from Peterson et al. 2016 and Shah et al. 2006.
Open calculator →Body Recomposition Planner
Combine your protein target with a small calorie deficit and a sensible training stimulus to gain muscle and lose fat at the same time.
In developmentWhy these tools exist
Most fitness calculators online are built to capture an email address or sell a supplement. The numbers they produce are often cribbed from secondary sources, padded for safety, or tuned to push you toward a product. We took the opposite approach.
Each tool here cites the studies it relies on. The defaults match peer-reviewed consensus where consensus exists, and ranges where it doesn't. The tools run entirely in your browser. We don't store your inputs, don't track your results, and don't gate the output behind a signup form.
Frequently asked questions
Are these calculators really free?
Yes. Every FitCraft calculator at /tools/ is free. There is no signup, no email gate, no upsell, and no ads. The calculators run entirely in your browser, so you can use them as many times as you want without an account.
Do you store my measurements or share my data?
No. The calculators run entirely client-side in your browser. Your weight, height, neck, waist, and any other measurement you type never leaves your device. We do not transmit, log, or store any input, and there are no tracking pixels wired to the calculators themselves.
How accurate are these calculators compared to a DEXA scan or lab test?
It depends on which calculator. The protein, TDEE, and macro calculators return evidence-based ranges grounded in peer-reviewed meta-analyses (Morton et al. 2018 in the British Journal of Sports Medicine for protein; Mifflin-St Jeor 1990 in the American Journal of Clinical Nutrition for energy expenditure). The body fat calculator uses the US Navy circumference method, which Hodgdon and Beckett 1984 validated against hydrostatic underwater weighing at r=0.90 with a standard error of 3 to 4 percentage points. None of these substitutes for a clinician-administered DEXA, BIA, or hydrostatic measurement, but among at-home methods that need no equipment, they are as accurate as the field gets.
Which calculator should I use first?
It depends on your goal. For body composition, start with the body fat calculator (or BMI plus waist-to-height as a no-tape alternative), then layer in the protein and TDEE calculators. For training, the 1 rep max calculator helps you set the right loads. For nutrition planning, run TDEE first to find your maintenance calories, then use the macro calculator to split that across protein, fat, and carbs. Most people benefit from running protein + TDEE together as the core duo.
Are these calculators medical advice?
No. The calculators are educational tools for healthy adults that produce evidence-based starting points, not personalized prescriptions. They are not a substitute for medical advice from a physician, registered dietitian, or other qualified clinician. People who are pregnant or breastfeeding, recovering from disordered eating, or who have chronic kidney disease, diabetes, or other diagnosed metabolic conditions should defer to their care team rather than to a generic web tool.
Who designed these calculators?
Domenic Angelino, MS Kinesiology, MPH (Brown University), NSCA-CSCS, ACE CPT. He is FitCraft's Chief Exercise Scientist. Domenic selected the formulas, set the multipliers from primary peer-reviewed sources, and reviewed each calculator before launch. He has been published in the Journal of Strength and Conditioning Research, Medicine and Science in Sports and Exercise, and Frontiers in Physiology, and featured in TIME, Newsweek, Forbes, and TODAY.com.
Why so many calculators instead of one?
Different questions need different math. Protein intake, daily calories, body fat percentage, and one-rep max all use different equations from different peer-reviewed sources. Combining them into a single tool would either oversimplify the math (giving worse answers) or overwhelm the interface (asking thirty inputs to fill a screen with numbers no one looks at). Each calculator does one thing well, cites the specific paper that supports it, and links to companion calculators when they are useful together.