BODY · ENERGY · STRENGTH · CARDIO · RECOVERY

CALCULATE IT. THEN DO IT.

Free health & fitness calculators, guided at-home sessions,
and gear we've actually tested. No signup, no fluff.

POPULAR

45 CALCULATORS

6.4M RUNS / MONTH

100% FREE · NO SIGNUP

DAILY ENERGY & MACROS LIVE

SEX

UNITS

AGE

WEIGHT (LB)

HEIGHT

ACTIVITY

GOAL

2,693

KCAL / DAY · HOLD

Protein 139g

Carbs 332g

Fat 90g

Mifflin–St Jeor estimate. BMR 1,737 · TDEE 2,693 kcal.

THE INDEX · EVERY INSTRUMENT

THE WHOLE TOOLKIT

Forty-five free calculators, by department. Run-counts are this month's.

BODY & COMPOSITION

Measure where you stand

9 TOOLS

01 BMI Body mass index, with healthy-range band 980k 02 Body Fat % U.S. Navy tape method estimate 301k 03 BMR Resting energy, Mifflin–St Jeor 274k

04 Ideal Weight Four classic formulas, side by side 188k 05 Lean Body Mass Fat-free mass from weight & BF% 122k 06 Waist-to-Hip Ratio A simple cardiometabolic risk proxy 96k

07 Body Surface Area Du Bois & Mosteller, m² 61k 08 Frame Size Wrist-based small / medium / large 48k 09 Army Body Fat % NEW U.S. Army circumference method (AR 600-9) New

ENERGY & NUTRITION

Fuel the work

9 TOOLS

10 TDEE / Calories Daily burn — our most-used tool 1.1M 11 Macro Splitter Protein / carb / fat grams by goal 612k 12 Protein Intake Grams per day from bodyweight 340k

13 Water Intake Daily fluid target by weight & sweat 219k 14 Calorie Deficit Loss rate from a chosen deficit 203k 15 Maintenance Calories Hold-steady intake at your activity 158k

16 Meal Calories Split a daily target across meals 74k 17 Carb Cycling High / low day carbs around training 52k 18 Fiber Target NEW Daily fiber from energy intake New

STRENGTH & TRAINING

Move heavier, smarter

9 TOOLS

19 One-Rep Max Epley & Brzycki, with % chart 388k 20 Wilks / DOTS Score Compare lifts across bodyweights 141k 21 Plate Loader What to put on each side of the bar 133k

22 Training Volume Sets × reps × load, per muscle 98k 23 Powerlifting Total Squat + bench + deadlift, ranked 87k 24 Strength Standards Novice → elite by lift & weight 76k

25 RPE Converter RPE ↔ % of 1RM, reps in reserve 58k 26 Warm-up Sets Ramp-up scheme to your top set 41k 27 Rest Timer Calc NEW Rest by goal: strength vs hypertrophy New

CARDIO & ENDURANCE

Go further, faster

9 TOOLS

28 Pace Calculator Time, distance & pace, any unit 204k 29 VO₂ Max Estimate from a field or race test 167k 30 Heart-Rate Zones Five zones from max or reserve 155k

31 Race Time Predictor Riegel projection across distances 112k 32 Running Calories Burn by pace, weight & distance 99k 33 Treadmill Pace Speed ↔ pace, with incline offset 68k

34 Marathon Splits Even or negative-split pace bands 57k 35 Cycling Power Watts, W/kg & FTP estimate 44k 36 Calories Burned NEW Energy used by any activity & MET value New

RECOVERY & WELLNESS

Adapt, don’t just grind

9 TOOLS

37 Sleep Cycle Best bed / wake times by 90-min cycles 186k 38 Sleep Debt Accumulated shortfall vs your need 142k 39 Max Heart Rate Tanaka & 220-age, compared 131k

40 Hydration Fluid & electrolyte loss replacement 88k 41 Steps → Calories Energy burned from a step count 79k 42 Daily Step Goal Target steps for your activity goal 66k

43 Caffeine Timing Cut-off for a clean night’s sleep 54k 44 Recovery Score NEW Readiness from sleep, soreness & HRV New 45 Nap Timer NEW Ideal nap length to wake without grogginess New

WORKOUTS & RECOVERY · GUIDED SESSIONS

THEN DO IT

Free, follow-along sessions that coach you move by move — name the move, cue the form, time it, and tell you what's next. No account, no streak, works offline. Start with the moment you're in.

Browse all sessions →

STRESSED OR WIRED Breathe Box breathing, 4-7-8, coherent breathing — each inhale and exhale paced for you. Start → GOT 10 MINUTES Quick workout A no-equipment bodyweight circuit, coached move by move with timed work and rest. Start → STIFF FROM SITTING Loosen up A guided stretch and mobility flow that undoes screen slump in a few minutes. Start → CAN'T SWITCH OFF Wind down A long-exhale 4-7-8 session to slow the breath and settle before sleep. Start →

RANKINGS

Ranked from the test bench — re-scored each quarter

16 RANKED

Best smartwatches, tested on-wrist · 16 watches logged for GPS accuracy, heart-rate tracking and real-world battery.

COMPARISONS

Head-to-head, spec for spec

6 MATCHUPS

This week: Oura Ring 4 vs Ultrahuman Ring Air — price, specs and our verdict, side by side.

CHALLENGER

ULTRAHUMAN RING AIR

Oura-class sleep data with no membership; the app is busier and metabolic features are still maturing.

8.6

CHAMPION

OURA RING 4

Best-in-test sleep staging and HRV, the most polished app — held back only by the monthly fee.

9.0 ✓ WINNER

Spec	♜ WINNER Oura Ring 4	Ultrahuman Ring Air
PRICE	$349	$349
BATTERY LIFE	~7 days	~6 days
FORM	Titanium ring	Titanium ring
SLEEP TRACKING	Best-in-test staging	Strong
SUBSCRIPTION	Required ($5.99/mo)	None
WATER RESISTANCE	100m	100m
FITHQ SCORE	9.0 / 10	8.6 / 10

CALCULATE IT. THEN DO IT.

THE WHOLE TOOLKIT

BODY & COMPOSITION

ENERGY & NUTRITION

STRENGTH & TRAINING

CARDIO & ENDURANCE

RECOVERY & WELLNESS

THEN DO IT

RANKINGS

COMPARISONS

ULTRAHUMAN RING AIR

OURA RING 4

Published formulas

Expert-reviewed

Free & private

Affiliates disclosed

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