Health & Fitness Calculators

Each calculator is designed for a specific decision: setting a calorie target, choosing a macro split, planning training zones, or interpreting common measurements. Start with the tool that matches your goal:

• BMI Calculator — a quick weight-status screening metric based on height and weight.
• BMR Calculator — an estimate of calories your body uses at rest.
• TDEE Calculator — daily calorie needs including activity (useful for bulking/cutting).
• Macronutrients Calculator — protein, carbs, and fats tailored to your target calories.
• Water Intake Calculator — a practical hydration target based on body size and lifestyle.
• Heart Rate Calculator — estimates max heart rate and training zones for structured cardio.
• Running Pace Calculator — pace, speed, and split times for training and race planning.
• Body Fat Calculator — a body fat % estimate (useful alongside weight trends).
• Ideal Weight Calculator — a range-based reference point (not a single “perfect” number).
• Pregnancy Due Date Calculator — an estimated due date (EDD) based on common date methods.
• Ovulation Calculator — a fertility window estimate using cycle-length assumptions.
• Blood Sugar Converter — converts mg/dL ↔ mmol/L for glucose readings.

If your goal is weight loss or weight gain, your best starting point is TDEE (maintenance calories). From there:

• Fat loss: try a moderate deficit and adjust based on weekly trends.
• Muscle gain: use a small surplus and prioritize strength training.
• Performance: you may sit near maintenance and periodize intake around training.

Because daily weight fluctuates (water, glycogen, digestion), use weekly averages and re-check your assumptions after ~2–3 weeks.

Once you have a calorie target, the Macronutrients Calculator helps you convert calories into grams of protein, carbs, and fat.

• Protein supports muscle retention and satiety (especially in a deficit).
• Carbs can improve training quality and endurance performance.
• Fats support hormones and help make the plan sustainable.

The “best” split depends on preference, adherence, and training demands—use the calculator as a baseline, then iterate.

For endurance training, start with heart rate zones to set intensity and running pace to plan workouts and race splits.

• Zones are estimates; refine them using perceived effort and real performance.
• Pace helps structure intervals, tempo runs, and long runs with clear targets.
• Calorie burn varies a lot—treat it as an estimate, not a guaranteed number.

These calculators use widely accepted equations and unit conversions. They produce estimates—use them as a baseline and iterate based on real outcomes.

• BMI: BMI = weight (kg) / height (m)^2
• BMR: commonly estimated via equations such as Mifflin–St Jeor (inputs like age, sex, height, weight).
• TDEE: typically estimated as BMR × activity factor (activity multipliers reflect average daily movement/exercise).
• Macros: calories are translated to grams using standard energy densities: protein/carbs ≈ 4 kcal/g, fat ≈ 9 kcal/g.
• Blood glucose units: for glucose, mmol/L = mg/dL ÷ 18 (and mg/dL = mmol/L × 18).
• Pregnancy due date / ovulation: date-based estimates using typical cycle timing assumptions; individual variation can be significant.

Important: if you’re managing a medical condition, are pregnant, or have symptoms, these tools are not a substitute for professional care.

These tools provide evidence-based estimates, but accuracy depends on your inputs and the model assumptions. For best results:

• Use consistent measurements (same scale, similar time of day, similar hydration).
• Choose a realistic activity level (overestimating activity is the #1 cause of inflated TDEE).
• Track trends, not single values — weekly averages are more informative than one-off readings.
• Recalculate after changes (weight changes, training volume changes, pregnancy week changes).

If you’re using these calculators for nutrition planning, a simple workflow is: estimate BMR → estimate TDEE → pick a calorie goal → set macros. Then adjust based on real-world progress.

• BMI: a screening tool; it doesn’t measure body composition (muscle vs fat).
• BMR: the “baseline” energy use; helpful but not the final daily target.
• TDEE: your best starting point for weight maintenance calories.
• Macros: protein supports muscle retention; carbs/fats can be adjusted to preference and training.
• Heart rate zones: estimates; use perceived effort and performance feedback to refine.

Note: these calculators are for informational purposes and do not replace medical advice. If you have health conditions, take medications, have disordered eating concerns, or are pregnant, confirm targets with a qualified professional.

If you want to validate assumptions or go deeper, these references are a good place to start:

• CDC: Body Mass Index (BMI)
• NIDDK (NIH): Weight management
• CDC: Measuring physical activity (intensity)
• American Diabetes Association: Diabetes resources (glucose context)
• ACOG: Pregnancy timeline and fetal development (context for date estimates)

We link to third‑party resources for context; always follow guidance from your clinician for medical decisions.