About CalcFit Health Calculators

CalcFit Health Calculators is a collection of fast, accurate, and privacy-friendly online calculators that estimate key health and fitness metrics. Beyond BMI, BMR, TDEE, Body Fat %, and Daily Calories, the suite now includes performance, cardiometabolic, and clinical tools such as VO₂ Max, Running Pace & Calories, 1RM, Blood Pressure Category, Cholesterol Ratios, GI/GL, eGFR, and Intermittent Fasting — plus Ovulation & Fertile Window and Quit Smoking Savings for planning and lifestyle impact — along with practical tools for Alcohol Units, Added Sugar, Sodium, Fiber Intake, Walking Calories, Resting Heart Rate, Fitness Age, BBT tracking, and Stress/Burnout screening.

Our Mission

Make evidence-based health calculations accessible to everyone — with no account creation, tracking, or input storage. Each calculator is designed to be fast, mobile-first, and clear, so you can make better decisions with confidence.

Formulas & Methods We Use

• BMR: Mifflin–St Jeor
• TDEE: Standard activity multipliers
• Body Fat %: U.S. Navy circumference method
• LBM: Boer formula
• BSA: Mosteller formula
• Ideal Weight: Devine formula
• Pregnancy Due Date: Naegele’s rule
• MAP: MAP ≈ (SBP + 2×DBP) / 3
• Blood Pressure Category: classification by commonly used ranges (Normal/Elevated/Stage 1/2/Crisis)
• VO₂ Max: field-test–style estimations compatible with HR zones (explanatory output)
• Running Calories: speed → METs (Compendium of Physical Activities) with interpolation
• Walking Calories: standard MET equation (kcal = MET × 3.5 × weight(kg) ÷ 200 × minutes); MET by walking speed
• 1RM: Epley, Brzycki, Lombardi, O’Conner, Mayhew, Wathan (with Training Max guidance)
• GI/GL: GL = (GI × available carbs in grams) ÷ 100; GI categories Low/Medium/High
• eGFR: CKD-EPI 2021 (creatinine, race-free), with G1–G5 staging
• Cholesterol Ratios: Total/HDL, LDL/HDL, TG/HDL; conversions mg/dL ↔ mmol/L
• Intermittent Fasting: schedule planner (16:8, 18:6, 20:4, 14:10, 12:12, OMAD, custom)
• Ovulation & Fertility: LMP-based cycle estimation with average luteal phase (typically 12–16 days); fertile window ≈ 5 days before ovulation + ovulation day
• BBT / Ovulation: coverline = (highest of previous 6) + 0.05 °C; three consecutive highs above coverline ⇒ ovulation ≈ day before first rise
• Resting Heart Rate (RHR): reference bpm ranges; optional VO₂max via Uth–Sørensen (≈ 15.3 × HRmax / RHR)
• Fitness Age: educational model adjusting chronological age with BMI, WHtR, RHR, weekly activity; VO₂max (if provided) weighs cardiometabolic component
• Fiber Intake: Adequate Intake (AI) by age/sex or rule of 14 g / 1000 kcal; outputs total, target, % of target, gap/surplus
• Sodium / Salt: Na ↔ NaCl conversion (salt [g] ≈ Na [g] × 2.5); comparison vs common 1500–2300 mg/day limits
• Sugar Intake: total added sugars (g) vs WHO/AHA guidance; 1 tsp ≈ 4 g
• Alcohol Units: units = (volume × %ABV × 0.8) ÷ 10 (UK standard); day/week totals
• Stress / Burnout: 10-item Likert 0–4; total 0–40 with bands: Low (0–13), Moderate (14–26), High (27–40)
• Life Expectancy: educational longevity estimate based on population averages and lifestyle factors (not diagnostic)
• Quit Smoking Savings: Daily cost = (cigarettes/day ÷ cigarettes per pack) × price per pack; month ≈ ×30, year = ×365

Accuracy & Transparency

Calculations are based on widely referenced equations and public guidance from medical and nutrition literature. Results are estimates and should not replace personalized advice from a qualified healthcare professional. Always consider your individual context, measurements over time, and professional guidance.

Privacy

We do not collect or store personal inputs. All calculations run locally in your browser using client-side JavaScript. Our focus is on clarity, speed, and respecting your privacy.

Contact & Feedback

Suggestions or found an issue? Contact Us. We appreciate community feedback and continuously improve the tools.