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BMI Checker

BMI Checker

Section titled “BMI Checker”

Check your BMI instantly and receive immediate feedback on your weight category with personalized health recommendations and ideal weight ranges.

kg
cm

Use Cases

Section titled “Use Cases”

This BMI checker is perfect for quick health screenings, tracking weight loss progress, assessing fitness goals, pre-employment health checks, sports team evaluations, and routine health monitoring.

What is a BMI Check?

Section titled “What is a BMI Check?”

A BMI check is a fast assessment using your height and weight to determine your body mass index and weight category. It provides immediate insight into whether you’re underweight, normal weight, overweight, or obese.

Quick BMI Check Formula

Section titled “Quick BMI Check Formula”

Metric (kg, cm):

BMI=Weight (kg)(Height (cm)100)2\text{BMI} = \frac{\text{Weight (kg)}}{\left(\frac{\text{Height (cm)}}{100}\right)^2}

Imperial (lbs, inches):

BMI=Weight (lbs)×703Height (inches)2\text{BMI} = \frac{\text{Weight (lbs)} \times 703}{\text{Height (inches)}^2}

Math.js Expression:

# Quick metric check
weight = 72;
height = 170;


bmi = weight / ((height/100)^2);
bmi  # 24.91


# Quick imperial check
weight_lbs = 160;
height_inches = 67;


bmi = (weight_lbs * 703) / (height_inches^2);
bmi  # 25.06

BMI Categories Quick Reference

Section titled “BMI Categories Quick Reference”
BMICategoryAction Needed
< 18.5Underweight⚠️ Increase calorie intake
18.5 - 24.9Normal✅ Maintain current weight
25.0 - 29.9Overweight⚠️ Consider weight loss
30.0 - 34.9Obese I⚠️ Weight loss recommended
35.0 - 39.9Obese II❌ Medical supervision needed
≥ 40.0Obese III❌ Urgent medical attention

Instant BMI Assessment

Section titled “Instant BMI Assessment”

Check Your BMI in 3 Steps

Section titled “Check Your BMI in 3 Steps”
  1. Enter Weight: Input your current weight in kg or lbs
  2. Enter Height: Input your height in cm or inches
  3. Get Result: Instantly see your BMI and category

Understanding Your Result

Section titled “Understanding Your Result”

Your BMI check provides:

  • Exact BMI number (e.g., 24.3)
  • Weight category (Underweight/Normal/Overweight/Obese)
  • Health risk level (Low/Moderate/High/Very High)
  • Recommended actions (Maintain/Lose weight/Gain weight)

Example BMI Checks

Section titled “Example BMI Checks”

Example 1: Normal Weight Check

Section titled “Example 1: Normal Weight Check”

Input:

  • Weight: 68 kg (150 lbs)
  • Height: 172 cm (5’8”)
weight = 68;
height_m = 1.72;


bmi = weight / (height_m^2);
bmi  # 22.99

Result: ✅ BMI 22.99 = Normal Weight (Healthy)

Example 2: Overweight Check

Section titled “Example 2: Overweight Check”

Input:

  • Weight: 88 kg (194 lbs)
  • Height: 175 cm (5’9”)
weight = 88;
height_m = 1.75;


bmi = weight / (height_m^2);
bmi  # 28.73

Result: ⚠️ BMI 28.73 = Overweight (Consider 5-10% weight loss)

Example 3: Ideal Weight Check

Section titled “Example 3: Ideal Weight Check”

Question: What weight gives BMI 22?

Given: Height 168 cm

target_bmi = 22;
height_m = 1.68;


ideal_weight = target_bmi * (height_m^2);
ideal_weight  # 62.08 kg (137 lbs)

Result: Target weight for BMI 22 = 62 kg

Examples

Section titled “Examples”
  • 75 kg, 180 cm → BMI = 23.1 ✅ Normal
  • 95 kg, 175 cm → BMI = 31.0 ⚠️ Obese Class I
  • 55 kg, 165 cm → BMI = 20.2 ✅ Normal
  • 110 kg, 180 cm → BMI = 33.9 ⚠️ Obese Class I
  • 48 kg, 160 cm → BMI = 18.8 ✅ Normal (low end)

Healthy Weight Ranges by Height

Section titled “Healthy Weight Ranges by Height”

Metric (for BMI 18.5-24.9)

Section titled “Metric (for BMI 18.5-24.9)”
HeightHealthy Weight Range
150 cm (4’11”)41.6 - 56.1 kg (92-124 lbs)
160 cm (5’3”)47.4 - 63.7 kg (104-140 lbs)
170 cm (5’7”)53.5 - 72.0 kg (118-159 lbs)
180 cm (5’11”)59.9 - 80.7 kg (132-178 lbs)
190 cm (6’3”)66.8 - 89.9 kg (147-198 lbs)

Imperial (for BMI 18.5-24.9)

Section titled “Imperial (for BMI 18.5-24.9)”
HeightHealthy Weight Range
5’0” (60 in)95-128 lbs (43-58 kg)
5’4” (64 in)108-145 lbs (49-66 kg)
5’8” (68 in)122-164 lbs (55-74 kg)
6’0” (72 in)137-184 lbs (62-83 kg)
6’4” (76 in)154-205 lbs (70-93 kg)

Quick Health Recommendations

Section titled “Quick Health Recommendations”

If Underweight (BMI < 18.5)

Section titled “If Underweight (BMI < 18.5)”
  • ✅ Eat more frequent, calorie-dense meals
  • ✅ Include healthy fats (nuts, avocados, olive oil)
  • ✅ Strength training to build muscle mass
  • ✅ Consult doctor to rule out medical issues

If Normal Weight (BMI 18.5-24.9)

Section titled “If Normal Weight (BMI 18.5-24.9)”
  • ✅ Maintain balanced diet
  • ✅ Exercise 150 minutes per week
  • ✅ Monitor weight quarterly
  • ✅ Annual health checkups

If Overweight (BMI 25.0-29.9)

Section titled “If Overweight (BMI 25.0-29.9)”
  • ⚠️ Reduce calorie intake by 500 cal/day
  • ⚠️ Increase physical activity to 200-300 min/week
  • ⚠️ Focus on whole foods, reduce processed foods
  • ⚠️ Track progress monthly

If Obese (BMI ≥ 30.0)

Section titled “If Obese (BMI ≥ 30.0)”
  • ❌ Consult healthcare provider immediately
  • ❌ Structured weight loss program
  • ❌ Consider nutritionist/dietitian support
  • ❌ Medical supervision for exercise program
  • ❌ Evaluate for weight loss medication or surgery

BMI Check Frequency

Section titled “BMI Check Frequency”

General Health Monitoring

Section titled “General Health Monitoring”

Frequency: Every 3-6 months

Purpose: Track long-term trends, catch weight changes early

Active Weight Management

Section titled “Active Weight Management”

Frequency: Monthly or bi-weekly

Purpose: Monitor progress, adjust strategies, maintain motivation

Post-Lifestyle Change

Section titled “Post-Lifestyle Change”

Frequency: Weekly for first month, then monthly

Purpose: Ensure healthy rate of change (0.5-1 kg/week)

Medical Supervision

Section titled “Medical Supervision”

Frequency: As prescribed by healthcare provider

Purpose: Monitor treatment effectiveness, adjust medications

Common Mistakes & Tips

Section titled “Common Mistakes & Tips”

Checking BMI After Meals: Weight fluctuates throughout the day. For consistency, check BMI first thing in the morning before eating.

Using Different Scales: Different scales can show different weights. Use the same scale in the same location for accurate tracking.

Forgetting to Remove Heavy Clothing: Shoes, jackets, and heavy clothes add weight. Weigh yourself in minimal clothing for accuracy.

Checking Too Frequently: Daily weight fluctuates due to water, food, hormones. Check weekly or monthly for meaningful trends.

Panicking Over One Check: A single BMI check is a snapshot. Focus on trends over time, not one-time measurements.

Ignoring How You Feel: BMI is one metric. Also consider energy levels, fitness, how clothes fit, and overall health markers.

Frequently Asked Questions

Section titled “Frequently Asked Questions”

How often should I check my BMI?

Section titled “How often should I check my BMI?”

For general health, check every 3-6 months. If actively managing weight, check monthly. Avoid daily checks as normal weight fluctuations can be misleading.

Is my BMI check result accurate?

Section titled “Is my BMI check result accurate?”

BMI checks are accurate calculations based on height and weight, but BMI itself has limitations. It doesn’t measure body fat percentage or muscle mass directly.

What time of day should I check my BMI?

Section titled “What time of day should I check my BMI?”

Check in the morning before eating for most consistent results. Weight can fluctuate 2-4 lbs throughout the day due to food, water, and bathroom use.

Can I check my BMI without a scale?

Section titled “Can I check my BMI without a scale?”

No, you need your current weight for accurate BMI calculation. Consider getting a home scale or using one at a gym or pharmacy.

Should I check BMI or body fat percentage?

Section titled “Should I check BMI or body fat percentage?”

Both are useful. BMI is easier to check and good for general screening. Body fat percentage is more accurate for athletes and those with high muscle mass.

What if my BMI is on the borderline?

Section titled “What if my BMI is on the borderline?”

Borderline BMI (e.g., 24.8 or 25.1) means you’re near a category threshold. Use additional metrics like waist circumference and overall health to assess risk.

Section titled “Related Calculators”