Health Calculation Guides & Formula References
All 24 formula reference guides explain formulas, ranges, classification systems, and standard public data sources. Each page includes historical context, worked arithmetic examples, and explicitly cited references. Zero personal guidance is provided. Source consortia referenced include CDC, WHO, NIH, USDA, NSF, AASM, and the Ainsworth Compendium of Physical Activities.
All Formula Reference Guides
BMI Formula and Standard Ranges
How BMI is calculated, WHO vs CDC categories, adult vs pediatric percentile differences, and the Quetelet index origin.
BMR and TDEE Calculation Methods
Mifflin-St Jeor vs Harris-Benedict equations, five activity factor definitions, Katch-McArdle variant with fat-free mass.
Body Fat Estimation Formulas
BMI method, US Navy circumference method, skinfold references, and population comparison distribution notes.
MET Values and Exercise Calories
Compendium of Physical Activities MET reference table and the (MET × kg × minutes / 200) calorie formula.
Daily Water Intake Standards
US IOM and EFSA reference values, weight-based, temperature and activity adjustment factors by source.
Sleep Cycles and Duration Ranges
90-minute ultradian cycle, NREM/REM stage percentages, and NSF age-group duration references.
CDC Pediatric BMI Percentiles
Age- and sex-specific BMI-for-age percentile curves (2–19 years) and interpretation conventions.
Height-Weight Reference Tables
Height-to-weight conversion based on BMI 18.5–24.9 interval, with population distribution notes.
Our Data Sources
Where every formula, range and constant comes from — CDC, WHO, NIH, USDA, NSF, AASM public datasets.
Adult BMI Ranges 2025 (WHO vs CDC)
Detailed WHO 1995–2000 and CDC adult BMI classification cutoffs, obese class I/II/III sub-ranges and regional thresholds.
Teen BMI Percentiles (CDC Growth Charts)
CDC 2000 BMI-for-age 5th/85th/95th percentile definitions, boys vs girls reference curves and 2–19 age weight status ranges.
BMR vs RMR Formulas 2025
Mifflin-St Jeor 1990, Harris-Benedict 1984 Roza-Shizgal revision and Katch-McArdle lean-mass equations compared with worked examples.
TDEE Activity Factor Levels
NIH/IOM DRI definitions for the five PAL multipliers (sedentary 1.2 through extra active 1.9), step count maps and TDEE × level calculation table.
Body Fat % 2025 (Navy vs BMI vs DEXA)
US Navy circumference method, Deurenberg BMI-derived formula and DEXA reference accuracy ranges with NHANES population correlation data.
Ideal Weight Formulas (4 Equations)
Hamwi 1964, Devine 1974, Robinson 1983 and Miller 1983 IBW formulas side-by-side 5'0"–6'4" height table and 5'8" worked case.
Height-Weight Ratio Tables 2025
150–190 cm × 40–110 kg WHO BMI colored category grid plus NHANES 2017–2020 male/female population mean cross-tabs.
MET Values 2024 Compendium
2024 Ainsworth Compendium 25+ activity MET table, running/swimming/cycling/strength/yoga rows, 60/70/80 kg × 8 activities calorie burn matrix.
3500 kcal/lb Rule & NIH Model (2024)
Wishnofsky 1958 adipose energy density origin, NIDDK Pennington body-weight planner model, adaptive thermogenesis notes and 3 TDEE/intake worked deficit cases.
Food Calorie Reference Table (USDA 2025)
30+ USDA FoodData Central FNDDS 2023-2024 rows (kcal/100 g, protein, fat, carbs, fiber), Atwater 4-4-9 factor derivation example.
Weekly/Monthly Calorie Budget 2025
Steady-state TDEE × 7 weekly budget, TDEE × 30.4167 monthly baseline, 5 TDEE-level reference table and weekday/weekend variance ranges.
Water Intake Formula 2025 (IOM/EFSA)
30–35 mL/kg base, 4-tier Celsius temperature correction, 4-tier activity multiplier, IOM 2.7/3.7 L & EFSA 2.0/2.5 L references and food moisture % table.
90-Minute Sleep Cycle Calculator
Kleitman BRAC origin, AASM 2020 sleep stages, 14-min onset latency, wake-time × 4/5/6 cycles bedtime reverse table and 11:30 PM forward wake-times.
Sleep Hours by Age Chart 2025
CDC 2025 0–3 mo through 65+ y age-group ranges, AASM/SRS 2015 RAND consensus columns (recommended / maybe / not recommended).
Sedentary Time & Daily Routine 2025
WHO 2020 GAPPA guidelines, 150–300 min moderate aerobic thresholds, 5-min/30-min sit-break references, 24-hour block planner sample schedule.
Categories
Body Composition
- BMI Formula and Standard Ranges (intro guide)
- Adult BMI Ranges 2025 — WHO vs CDC Cutoffs
- CDC Pediatric BMI Percentiles (overview)
- Teen BMI Percentiles — CDC 2000 Growth Charts
- Body Fat Estimation Formulas (overview)
- Body Fat % 2025 — Navy, BMI-Derived, DEXA
- Height-Weight Reference Tables (overview)
- Height-Weight Ratio Tables — WHO/NHANES
- Ideal Weight Formulas — Devine/Robinson/Miller/Hamwi
Metabolism & Calories
- BMR and TDEE Calculation Methods (overview)
- BMR vs RMR Formulas — MSJ vs Harris-Benedict
- TDEE Activity Factor Levels — NIH/IOM Definitions
- MET Values and Exercise Calories (overview)
- MET Values 2024 — Full Ainsworth Compendium
- 3500 kcal/lb Rule — NIH 2024 Body-Weight Model
- Weekly/Monthly Calorie Budget — Steady State
- Food Calorie Reference Table — USDA FoodData
Sleep, Hydration & Routine
- Sleep Cycles and Duration Ranges (overview)
- 90-Minute Sleep Cycle Calculator — Bedtimes/Wake-Ups
- Sleep Hours by Age — CDC/AASM/NSF 2025 Chart
- Daily Water Intake Standards (overview)
- Water Intake Formula — IOM Weight/Temp/Activity
- Sedentary Time & Daily Routine — WHO 2025 Guide
Standards & References
Featured Standards Table
| Standard / Formula | Source | Year |
|---|---|---|
| BMI = kg / m² (Quetelet) | WHO Global Database on BMI | 1832 / 1995 |
| Mifflin-St Jeor BMR equation | American Dietetic Assoc. Journal | 1990 |
| US Navy Body Fat Circumference | US Navy / DoD Health Affairs | 1984 |
| Ainsworth MET Compendium | ACSM Medicine & Science in Sports | 2011 (rev. 2024) |
| US IOM Water AI | Institute of Medicine DRI Series | 2004 |
| 90-min ultradian cycle / BRAC | Kleitman, Dement & Kleitman | 1953 / 1957 |
| Sleep Duration Ranges (age) | NSF / AASM & SRS Endorsement | 2015 / 2016 |
| CDC BMI-for-Age Percentiles | CDC / NCHS Growth Charts (2000) | 2000 |
| WHO Child Growth Standards | WHO Multicentre Growth Study | 2006 |
Pregnancy Reference Library (27 articles)
Purely descriptive reference articles. Population data, classification tables, numerical thresholds, formula origins, historical bibliography, public payment rates. No personal guidance.
1. Preconception
Preconception Preconception Timeline Reference: Standard 3–6 Month Pre-Pregnancy Checklist CategoriesStandard 3–6 month pre-pregnancy checklist categories and timeline reference table. Preconception Folic Acid Dosing Reference Tables: WHO / CDC / NHS / NICE / SOGC Public Ranges (2025)
WHO, CDC, NHS, NICE, SOGC 2025 public health folic acid dosing ranges by country. Preconception Preconception BMI Range Distribution: CDC NHANES 2017–2020 Population Percentile Tables
CDC NHANES 2017–2020 preconception BMI population percentile tables.
2. First Trimester
First Trimester First Trimester Gestational Reference: Weeks 0+0 through 13+6 Numerical TablesWeeks 0+0 through 13+6 first trimester numerical gestational reference tables. First Trimester Naegele's Rule Formula Derivation: EDD LMP + 280 Days Reference History
Naegele's rule EDD formula: LMP + 280 days, historical derivation and variants. First Trimester First Trimester Prenatal Screening Timeline: NT / cFTS / NIPT Gestational Windows
NT, cFTS, NIPT first trimester prenatal screening gestational window timeline. First Trimester Nausea and Vomiting Population Prevalence Rates: Peer-Reviewed Meta-Analysis Reference
Nausea and vomiting in pregnancy population prevalence meta-analysis rates.
3. Second Trimester
Second Trimester Fundal Height Measurement Reference Table: 14–40 Week Population Nomograms14–40 week fundal height measurement population nomogram reference table. Second Trimester Second Trimester Anomaly Scan: 18–22 Week Standard Gestational Window Reference
18–22 week second trimester anomaly scan standard gestational window. Second Trimester Gestational Diabetes Screening Thresholds: 24–28 Week OGTT Public Reference Cutoffs
24–28 week OGTT gestational diabetes screening public threshold cutoffs. Second Trimester Maternal Gestational Weight Gain Ranges: IOM 2009 BMI Category Tables
IOM 2009 maternal gestational weight gain ranges by BMI category tables.
4. Third Trimester
Third Trimester Fetal Weight Percentile Reference Curves: 28–42 Week INTERGROWTH-21st and Hadlock Tables28–42 week fetal weight percentiles: INTERGROWTH-21st and Hadlock curves. Third Trimester Third Trimester Visit Frequency Schedule: 28–40 Week Standard Clinic Timetables
28–40 week third trimester standard clinic visit frequency schedule. Third Trimester Group B Streptococcus (GBS) Screening Window Reference: 35+0–37+0 Weeks CDC 2020 Guideline
CDC 2020 GBS screening window reference: 35+0–37+0 weeks gestational age. Third Trimester Bishop Score Numerical Component Reference Table: Induction of Labor Readiness Scoring
Bishop score numerical component table for labor induction readiness scoring.
5. Labor & Birth
Labor & Birth Stages of Labor Duration Population Ranges: Friedman Curve vs. Zhang 2010 Contemporary Labor CurveFriedman curve vs Zhang 2010 contemporary stages of labor duration ranges. Labor & Birth Cesarean Section Rate by Country: WHO 2024 Global Dataset and 2016 10–15% Benchmark Reference
WHO 2024 global cesarean section rates by country and 2016 10–15% benchmark. Labor & Birth Apgar Score Numerical Component Reference: 0–10 Points at 1 and 5 Minutes (Virginia Apgar 1952)
Apgar score 0–10 components at 1 and 5 minutes, Virginia Apgar 1952.
6. Postpartum & Newborn
Postpartum & Newborn Postpartum Visit Timelines: WHO 2013 and ACOG 2018 2-Week / 6-Week WindowsWHO 2013 and ACOG 2018 postpartum visit 2-week and 6-week windows. Postpartum & Newborn Newborn Screening Panel Reference: PKU / CH / CAH / CCHD / Hearing Universal Public Programs
Universal newborn screening panel: PKU, CH, CAH, CCHD, hearing public programs. Postpartum & Newborn Postpartum Uterine Involution Reference: Fundal Height Regression Centimeters-by-Day Population Table
Postpartum uterine involution fundal height cm-by-day regression population table.
7. Benefits & Finance
Benefits & Finance Maternity Leave Duration and Payment Reference: OECD / ILO Employment Protection 2025 DataOECD / ILO 2025 maternity leave duration and payment employment protection data. Benefits & Finance Child Benefit and Family Allowance Public Rate Reference: 2025 US WIC / UK Child Benefit / Canada CCB / EU Countries
2025 public child benefit rates: US WIC, UK Child Benefit, Canada CCB, EU.
8. Tool Method Guides
Tool Method Guides LMP-to-EDD Calculation Methods: Naegele's Rule, 280-Day Constant, Cycle Length Adjustment Formula Deep DiveLMP-to-EDD methods: Naegele's rule, 280-day constant, cycle adjustment formulas. Tool Method Guides Current Pregnancy Gestational Age Calculation Methods: Today Reference Date vs LMP / EDD Formulae
Current gestational age calculation: today reference vs LMP / EDD formula methods. Tool Method Guides Pregnancy Trimester Division Standards and Periodization Milestones: WHO / ACOG / RCOG / SOGC Consensus
WHO, ACOG, RCOG, SOGC consensus pregnancy trimester division milestones. Tool Method Guides Prenatal Visit Schedule Models: WHO 2016 8-Visit vs. ACOG 2023 14-Visit Standard Comparison Tables
WHO 2016 8-visit vs ACOG 2023 14-visit prenatal schedule comparison tables.