BMI Health Hub
Simple tools • Real guidance

BMI Tool — Calculate BMI, Calories & Risks

Who this tool is for (and who it’s not)

Great fit if you want…

  • A quick BMI snapshot and a simple way to track trends.
  • Plain-language guidance and realistic next steps.
  • Links to practical habits: meal planning, sleep, and strength.

Start here: weekly checklist • meal planning

Not a fit if you need…

  • Medical diagnosis, treatment, or emergency guidance.
  • Child/teen BMI percentiles (adult BMI is different).
  • Exact body‑fat measurement (BMI is a screening tool).

If you’re unsure, read: FAQ • Editorial Policy

Educational information only. Not medical advice.

Enter your details

Your snapshot

Fill your details and click Calculate.

Risks & notes

    Tips

      How BMI is calculated

      BMI = weight (kg) ÷ [height (m)]². If you prefer pounds/feet, we convert behind the scenes.

      Metric example

      Weight 72 kg, Height 175 cm → 1.75 m

      72 ÷ (1.75 × 1.75) = 23.5 (Healthy)

      Imperial example

      Weight 160 lb, Height 5′9″ → 175.3 cm → 1.753 m

      72.6 ÷ (1.753 × 1.753) = 23.6 (Healthy)

      BMI is a screening tool, not a diagnosis. Combine with waist size, fitness, lab results, and clinical advice.

      BMR & TDEE explained

      BMR (Basal Metabolic Rate) estimates calories your body uses at rest. TDEE (Total Daily Energy Expenditure) is BMR multiplied by an activity factor to approximate daily needs.

      Activity levelFactorExamples
      Sedentary1.2Desk job, little intentional exercise
      Light1.3751–3 short workouts per week, regular walking
      Moderate1.553–5 moderate workouts per week
      Active1.7256–7 workouts/week or physical job
      Very active1.9Manual labor + training or athletic program
      Your calorie suggestion uses TDEE plus a small adjustment based on your BMI category.

      Category snapshots

      Underweight

      • Nutrient deficiencies
      • Low energy, reduced immunity
      • Consider supervised weight gain

      Healthy

      • Maintain balanced diet
      • 150+ min activity/week
      • Strength train 2–3×/week

      Overweight

      • Increased cardio‑metabolic risk
      • Prioritize sleep & fiber
      • Modest calorie deficit

      Obesity

      • Higher risk of diabetes, heart disease
      • Structured plan & support help
      • Focus on protein and vegetables

      Talk with a clinician for personalized guidance—especially if you have existing conditions.

      Practical recommendations

      Nutrition

      • Protein at each meal
      • 25–35 g fiber/day
      • Plan 2–3 “default” meals

      Movement

      • Daily step goal
      • 2–3 strength sessions
      • Short movement breaks

      Sleep & stress

      • 7–9 hours/night
      • Consistent schedule
      • Breathing or walk breaks

      Quick answers

      Is BMI accurate for athletes?

      Muscle adds weight without the same health risk as visceral fat. Check waist size and performance markers too.

      Should I cut calories aggressively?

      No. Large deficits backfire. Small, sustainable changes work best.

      See the full FAQ →

      Interpreting your results

      After you calculate, scan the Risks & Tips boxes to pick one or two actions for the next two weeks. Consistency beats intensity. If numbers look surprising, add a waist measurement and consider your current strength/cardio capacity.

      Common scenarios & actions

      If you're Underweight

      Add 300–400 kcal/day from whole foods, prioritize protein, and perform 2–3 strength sessions weekly.

      If you're Healthy

      Maintain intake, train strength, and keep sleep regular. Build resilience before chasing performance.

      If you're Overweight

      Try a modest 300 kcal/day deficit; push step count; anchor meals around protein and vegetables.

      If you have Obesity

      Work toward a 500 kcal/day deficit with support if needed. Make foods high in protein/fiber your default.

      Waist-to-Height ratio (optional)

      Optional context check: Waist‑to‑Height Ratio (WHtR). Many adults aim for under ~0.5. Measure at your navel after a normal exhale.

      How to measure

      • Stand tall; place a soft tape measure around the midpoint between last rib and hip bone.
      • Keep the tape horizontal and snug but not compressing skin.
      • Measure after a normal exhale; repeat 2–3 times and average.

      Safety & privacy

      Not medical advice. Use BMI as a screen alongside clinical guidance, especially if you have existing conditions, are pregnant, or are under 18.

      Your inputs are private and computed only in your browser. See Privacy for details.

      How to Use This BMI Tool

      1. Enter your height and weight using the same unit system.
      2. Double-check entries (e.g., 5′9″ = 69 inches, not 5.9).
      3. Calculate and note the result with the date for trend tracking.

      Interpreting Your Result

      Use BMI as a screening number. Pair it with a waist measure and fitness markers (walk pace, push-ups) to see the fuller picture.

      Example Calculations

      HeightWeightFormulaResult
      69 in170 lb703 × 170 ÷ 69²25.1
      175 cm70 kg70 ÷ 1.75²22.9

      Common Mistakes (and Fixes)

      • Mixing units → pick US or metric and convert first.
      • Using feet.decimals for height → convert to total inches or meters.
      • One-off numbers → track monthly averages instead.

      Beyond BMI

      Check waist-to-height ratio (aim for under ~0.5 for many adults), your resting heart rate, and your activity consistency to round out the story.

      Last Updated

      Last updated: November 08, 2025

      US vs Metric: Quick Reference

      InputUSMetric
      HeightTotal inches (e.g., 69)Meters (e.g., 1.75)
      WeightPounds (lb)Kilograms (kg)
      Formula703 × lb ÷ in²kg ÷ m²

      Result Ranges (Adults)

      • < 18.5 underweight
      • 18.5–24.9 healthy weight
      • 25.0–29.9 overweight
      • ≥ 30.0 obesity (classes vary)

      Use BMI with context like waist-to-height ratio and fitness markers.

      Trend Tracking Template

      DateWeightBMINotes
      (yyyy-mm-dd)(lb or kg)(calc)sleep, steps, meals, etc.

      Linking Next Steps

      Unit Conversion Cheats

      • Feet/inches → inches: 5′9″ = (5×12)+9 = 69 in
      • cm → meters: 175 cm = 1.75 m
      • lb → kg: lb ÷ 2.2046

      Edge Cases & Caveats

      BMI is less reflective at extremes of height, in pregnancy, and in very muscular athletes. Use extra context (waist, labs, performance) and talk to a clinician when unsure.

      Examples by Category (Adults)

      BMIExample (69 in / 175 cm)Notes
      18.4~125 lb / 56.7 kgUnderweight
      22.0~148 lb / 67.1 kgHealthy weight
      27.5~185 lb / 83.9 kgOverweight
      32.0~216 lb / 98.0 kgObesity (class I)

      Frequently Asked Questions

      • How precise is this calculator? It follows standard formulas; rounding is to one decimal for readability.
      • Can I save my results? Copy the trend table or save a screenshot; we don’t store personal entries.
      • Kids/teens? Use BMI‑for‑age percentiles instead.

      Accuracy & Limitations

      BMI estimates population risk and is one data point. Pair with waist‑to‑height ratio, activity, and clinical advice for a fuller picture.

      Accessibility & Mobile Tips

      • Use the tab key to move between inputs.
      • On mobile, rotate to landscape for larger buttons.
      • Screen readers: labels appear before fields.

      Interpreting BMI Like a Pro

      Your BMI category is a starting point, not the full story. Two people can share the same BMI while having different body composition, fitness levels, and health markers. To interpret results more accurately, consider pairing BMI with a waist measurement, your activity level, and how your weight has been trending over time.

      If you recently started lifting or playing a sport, your scale weight may rise while your waist shrinks—this can make BMI look “worse” even as health improves. In that case, focus on trend lines: waist, strength numbers, resting heart rate, and how you feel during daily activity.

      For fat loss, consistency beats intensity. A small calorie deficit combined with strength training and daily steps tends to outperform extreme dieting because it protects muscle and helps adherence. If your goal is weight gain, the same principle applies: a modest surplus, regular strength work, and adequate sleep to support recovery.

      Healthy Targets That Don’t Depend on Perfection

      Rather than chasing a single “ideal” number, aim for measurable routines: two to three strength sessions each week, a step goal you hit most days, and meals built around protein plus fiber. These habits improve body composition and metabolic health even if BMI changes slowly.

      Tool notes updated: January 8, 2026.

      Understanding your result

      Your BMI is calculated from your height and weight. It’s a fast screening metric, not a diagnosis. What matters most is how you use the result: as a starting line for practical decisions.

      What to do with a BMI number

      Instead of chasing a perfect target, choose a realistic next step based on your category and your context. For example, someone who lifts weights may use BMI as a trend line, while someone improving general health may pair it with waist size and resting heart rate.

      Common questions visitors ask

      Tip: save your result and re-check after 4 weeks of consistent habits. That’s enough time to see a meaningful trend.

      Interpreting BMI by context

      1) If you’re strength training

      BMI may read higher because muscle adds weight. Use BMI as a trend line and pair it with waist measurement or how your performance changes. If waist is stable or decreasing and strength is improving, your health trend may be positive even if BMI is flat.

      2) If you’re restarting movement

      Early changes often show up as better energy and appetite control. A realistic first target is simply consistency: 20–30 minutes of walking most days and two short strength sessions weekly.

      3) If you’re trying to gain weight

      If you’re underweight and trying to gain, focus on energy-dense additions you can keep: an extra snack daily, a liquid calorie option (milk/smoothie), and protein at each meal.

      Input accuracy: avoid the most common mistakes

      Most “weird” BMI results come from small input issues. Use these quick checks to ensure your result reflects reality.

      Checklist

      Better comparison method

      For progress, compare your BMI using the same measurement routine weekly. If you need a “single number,” use your weekly average weight instead of one random day.

      Accuracy and consistency make the tool more useful than obsessing over decimals.

      Common edge cases and how to handle them

      Not every visitor fits the “average” assumptions behind BMI. These edge cases are common, and you can still use the tool responsibly.

      If you’re very athletic

      Use BMI as a broad trend and add waist measurement or performance markers. Read: BMI vs. body fat.

      If you’re older or returning from inactivity

      Strength training and protein matter more to protect muscle. Start with a beginner strength plan and keep walking consistent.

      If your weight changes rapidly

      Large changes in a short time can reflect water shifts, illness, medication changes, or other factors. If you’re concerned—or have symptoms—get professional guidance.

      BMI vs. waist: a simple improvement you can add today

      BMI is based on height and weight. Waist measurement adds context because it can reflect changes in abdominal fat more directly. If you want a stronger “health trend” signal, track both.

      Waist measurement basics

      Many visitors find waist changes show up earlier than scale changes. If your waist is trending down while BMI is stable, your composition may be improving.

      Troubleshooting: when the result doesn’t match how you feel

      Sometimes a BMI category feels “wrong” compared to your energy, fitness, or appearance. Here are the most common reasons and what you can do:

      If you want a next step that doesn’t require intense dieting, start with calorie density and simple meal planning.

      Your 10-second unit check (prevents most errors)

      Before you trust any result, run this quick unit check:

      If your BMI seems surprising, don’t panic—recheck your inputs and compare week-to-week. For context, see BMI vs. body fat and consider adding a weekly waist measurement.

      Results note: what to record so you can improve

      Numbers are only useful when you can compare them. After you calculate BMI, record these four items (takes 30 seconds):

      Visitors who record context avoid overreacting to normal fluctuations. If you need a simple habit to start, use the weekly checklist.

      What to do after you calculate BMI

      After you get a BMI result, the best next step depends on your goal. Use this quick guide:

      The calculator gives you the number; the blog gives you the plan.