BMI Calculator

Calculate adult BMI from height and weight in imperial or metric units. See CDC-style category bands instantly — free, private, no signup.

Reviewed / updated August 4, 2026

Your inputs

lb

Result

Body mass index

24.4

CDC adult category: Healthy weight

BMI
24.39
Category
Healthy weight
Underweight
< 18.5
Healthy weight
18.5 – 24.9
Overweight
25 – 29.9
Obesity
30+

BMI 24.4 falls in the CDC “healthy weight” adult range (18.5–24.9). BMI is a screening tool, not a full health diagnosis.

Suggested next steps

  • Open the Calorie Calculator to estimate daily energy needs (BMR/TDEE) from the same height and weight inputs.
  • Re-check BMI if your weight or height measurement changes.
  • Use consistent units (all imperial or all metric) when comparing results over time.

How the BMI calculation works

Body mass index (BMI) relates weight to height:

  • Metric: kg ÷ (meters × meters)
  • Imperial: 703 × lb ÷ (inches × inches)

Enter height and weight, and the tool returns BMI plus a CDC-style adult category. Results update as you type. Rule-based explanations describe which band you fall into and remind you that BMI is a screening metric, not a full health diagnosis. Next-step tips point to the Calorie Calculator for energy-needs planning with the same height and weight inputs.

Worked example

Height 5 ft 10 in (70 inches), weight 170 lb:

  1. 70 × 70 = 4,900
  2. 703 × 170 = 119,510
  3. BMI = 119,510 ÷ 4,900 ≈ 24.4

That sits in the healthy weight adult range (18.5–24.9).

Metric check: 178 cm and 77 kg → 77 ÷ (1.78²) ≈ 24.3.

Methodology and notes

Categories follow commonly published CDC adult BMI ranges. Calculations run entirely in your browser. BMI is not medical advice and may be less informative during pregnancy or for some athletic body types. Talk with a qualified clinician about personal health decisions.

Frequently asked questions

How is BMI calculated?

Metric: BMI = weight (kg) ÷ height (m)². Imperial: BMI = 703 × weight (lb) ÷ height (in)². This calculator applies the matching formula for the unit system you select.

What are the CDC adult BMI categories?

Underweight is below 18.5; healthy weight 18.5–24.9; overweight 25–29.9; obesity 30 or higher. Categories are screening ranges for adults and do not diagnose health on their own.

Is BMI accurate for athletes?

BMI does not separate muscle from fat. Highly muscular people can land in overweight or obesity categories while having low body fat. Use BMI as one data point alongside clinical judgment.

Should children use this BMI calculator?

No. Children and teens need age- and sex-specific BMI percentiles, not adult cutoffs. Use a pediatric growth-chart tool or ask a clinician for youth assessments.

Related tools

Related calculators — live tools and upcoming pages for internal linking.