Metabolic Age Calculator

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This free Metabolic Age Calculator estimates your metabolic age — a simple way to compare your body’s energy-burning rate (BMR) to what’s typical for different ages. Enter a few details and get a metabolic age estimate, your BMR, and an optional TDEE range for planning.

⚡BMR (Mifflin–St Jeor) calculation

⏱️Metabolic age estimate (easy to interpret)

🔥Optional TDEE + calorie targets

📱Perfect for screenshots & sharing

Enter your details

Use realistic numbers for the best estimate. This tool runs entirely in your browser — nothing you type is sent anywhere.

Sex *

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Chronological age (years) *

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Height *

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Weight *

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Activity level *

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Goal (optional)

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Your metabolic age result will appear here

Enter both names and tap “Calculate Metabolic Age” to see your score.

This is an educational estimate based on common BMR equations. Use it as a directionally helpful guide, not a medical diagnosis.

Scale: metabolic age below your age = generally better metabolic efficiency · above your age = opportunity to improve fitness, muscle, and recovery.

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Metabolic age is an educational estimate. It does not diagnose health conditions and should not replace medical advice.

💑Fun soulmate snapshot

What you’ll get

A fast metabolic snapshot you can use to sanity-check your daily calorie needs and see whether your metabolism looks “younger” or “older” than your calendar age.

Estimated metabolic age (years) derived from BMR.
Your BMR (Basal Metabolic Rate) and a TDEE estimate by activity level.
Optional calorie targets for fat loss, maintenance, or muscle gain.

Pro tip: Try nicknames vs full names and see which one gives the most “this feels right” soulmate score.

⚠️Important note

Important health note

This tool is designed for educational use. Metabolic age is not a clinical diagnosis and can vary by method and device.

If you have a medical condition, pregnancy, or are under 18, talk to a clinician for personalized guidance.
Large changes in calories or exercise should be gradual and sustainable.
For fatigue, unexplained weight changes, or suspected hormone issues, get medical advice.

📚 Understanding metabolic age

What “metabolic age” means (and what it doesn’t)

Metabolic age is a popular way to describe how your body’s energy-burning rate compares to what’s typical at different ages. If your metabolic age comes out lower than your actual age, it generally suggests your resting metabolism looks more “youthful” — often seen in people with more lean muscle, higher daily movement, better cardiovascular fitness, and consistent sleep. If your metabolic age comes out higher, it doesn’t mean anything is “wrong” with you — it usually means there’s opportunity to improve the fundamentals that shape metabolism.

This calculator estimates metabolic age using your BMR (Basal Metabolic Rate) from the Mifflin–St Jeor equation, then compares that BMR to an age-based “expected” BMR at a reference healthy weight for your height. It’s a practical, easy-to-understand model that’s great for habit tracking, goal setting, and social sharing — but it’s not a medical test.

Why metabolic age changes

Lean mass: More muscle tends to increase resting energy needs; muscle is metabolically active tissue.
Body fat level: Very high body fat often correlates with lower relative fitness and less daily movement.
Activity & NEAT: “Non-exercise activity” (steps, standing, fidgeting) can change daily burn a lot.
Diet & recovery: Protein intake, sleep, stress, and consistency affect energy regulation and training quality.
Age & hormones: With age, muscle maintenance becomes more important; training and protein matter more, not less.

Quick interpretation guide

Metabolic age 5–10 years lower: Usually a good sign of fitness + lean mass relative to height.
Metabolic age near your age: Normal, especially if you’re consistent with movement and strength training.
Metabolic age 5–15 years higher: Common when activity is low or muscle mass is lower; focus on basics.

Note: Different devices and apps define metabolic age differently (some use body-fat estimates, others use bioimpedance). Treat your result as a trend metric — it’s most useful when you repeat it under similar conditions and watch it improve over time.

🧮 Formula breakdown

The exact math used in this calculator

Step 1 is calculating your BMR, which estimates the calories your body burns each day at rest. We use the widely used Mifflin–St Jeor equation:

Men: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5
Women: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age − 161

Step 2 estimates an “expected BMR” for different ages at a reference healthy weight for your height. We assume a reference BMI of 22 (a commonly used midpoint of the “normal” range) to create a consistent baseline. Reference weight:

Reference weight (kg) = 22 × (height(m))²

Then we solve the BMR equation for age to find the age at which your BMR would match the expected baseline:

Metabolic age ≈ (10×refWeight + 6.25×height + sexConstant − BMR) / 5
sexConstant = +5 (men) or −161 (women)

Step 3 (optional) estimates your TDEE (Total Daily Energy Expenditure) by multiplying BMR by your activity factor. This is helpful for calorie planning:

TDEE ≈ BMR × activityFactor

Real-life examples

Example A: 34-year-old man, 175 cm, 78 kg, moderately active. BMR might land around ~1,700–1,800 kcal/day. If that BMR resembles a younger baseline, metabolic age could be in the late 20s or early 30s.
Example B: 34-year-old woman, 165 cm, 78 kg, sedentary. BMR may be higher than baseline due to body mass, but metabolic age can still be higher if baseline comparison suggests lower relative efficiency.
Example C: 45-year-old who strength trains, walks daily, and sleeps well often sees metabolic age fall below 45 as lean mass and activity stay high.

The big win is not the exact number — it’s using the estimate to build a plan: add resistance training, increase steps, keep protein consistent, and make sleep a priority.

🚀 How to use your result

Turn your metabolic age into a simple weekly plan

Metabolic age is a “summary stat” — it responds to the same habits that improve almost everything else: energy, mood, body composition, and confidence. If you want a practical approach, use this 3-part system. It’s intentionally simple so you can stick with it.

1) Move daily (NEAT first)

Pick a step target you can hit most days (e.g., 6,000 → 8,000 → 10,000).
Use “movement snacks”: 5–10 minutes after meals, short walks, stairs, quick chores.
If you sit a lot, set a timer for 45–60 minutes and stand/walk for 2–3 minutes.

2) Strength train 2–4×/week

Focus on large movements: squat/hinge/push/pull/carry.
Progress slowly: add a rep, add a set, or add a little weight each week.
Muscle is your “metabolic savings account” — small deposits add up.

3) Eat for your goal (without chaos)

Fat loss: aim for ~10–20% below TDEE, prioritize protein, keep fiber high.
Maintain: hover near TDEE, keep training consistent.
Muscle gain: small surplus (~5–10%), lift progressively, sleep more.

Re-check your metabolic age every 2–4 weeks under similar conditions (same time of day, similar routine). If the trend improves — even slightly — you’re moving in the right direction.

If you’re chasing a very specific body composition goal, consider pairing this with a body fat estimate and a strength log. Metabolic age is a “dashboard light,” not the whole dashboard.

❓ FAQ

Frequently Asked Questions

Is metabolic age the same as body age?
People use the terms interchangeably, but methods differ. Some scales estimate “body age” using body-fat percentage and bioimpedance. This calculator estimates metabolic age using BMR math and a consistent height-based baseline.
Why did my metabolic age change after I started dieting?
Short-term calorie restriction can reduce energy expenditure (less body mass, less movement, and adaptive changes). That doesn’t mean you failed — it means you should diet slowly, keep protein high, and keep strength training to protect muscle.
What’s a “good” metabolic age?
Lower than your chronological age is commonly considered good. But the most useful comparison is you vs. you. Track the trend while improving steps, strength, and sleep.
How can I lower my metabolic age?
The fastest “high ROI” stack is: strength train 2–4×/week, raise daily steps, eat enough protein, reduce ultra-processed snacks, and sleep 7–9 hours. Most people see improvements within 6–12 weeks when consistent.
Is this accurate for athletes, older adults, or teens?
It’s directionally useful, but not perfect. Athletes with high muscle may show a “younger” metabolic age; older adults may benefit from using it as a motivation tool. Teens are still growing — use clinician guidance.
Does a higher metabolic age mean I have a slow metabolism?
Not necessarily. “Slow metabolism” is often misunderstood. The biggest controllable levers are muscle mass, activity (especially NEAT), and consistency. Use this as a starting point, not a label.

MaximCalculator provides simple, user-friendly tools. Always treat results as entertainment and double-check any important numbers elsewhere.