Thyroid BMR and TDEE Calculator: What Your Metabolism Actually Burns
Your real burn rate, with your thyroid included in the math:
Written and medically reviewed by Dr. Westin Childs, D.O. Last reviewed: August 28, 2026
How To Use This Calculator:
#1. Enter Your Stats
Age, height, weight, and how active you actually are. Be honest on the activity level, because that’s where most calculators get inflated.
#2. Pick Your Thyroid Situation
This is what makes this calculator different. It uses the same thyroid adjustments as my calorie calculator: untreated hypothyroidism suppresses your burn by about 15%, T4-only treatment with symptoms by about 10%, post-thyroidectomy by about 18%, and every standard calculator ignores all of it.
#3. Read Your Numbers
Your BMR (what you burn lying still), your TDEE (what you burn in a full day), and the thyroid-adjusted range that explains why the standard numbers never seem to work for you.
#4. Take It To The Calorie Calculator
Once you know what you burn, the Hypothyroid Calorie Calculator turns it into what to eat.
Why Thyroid Patients Need Their Own Metabolism Calculator
Your thyroid sets your resting metabolic rate. That’s its job.
So when it’s underactive, you burn less at rest than a standard formula predicts, and the size of the gap depends on your exact situation.[1][2]
Here’s what that means in practice: a standard calculator tells you 1,900 calories to maintain, you eat 1,700 to lose, and nothing happens, because your actual burn is closer to 1,700. You’re not doing it wrong. The number was wrong.
This calculator gives you both numbers: the standard prediction and the thyroid-adjusted range, so you can aim at the honest one. And as your treatment gets optimized, your burn recovers toward normal. Know that before you blame yourself for a slow month.
Frequently Asked Questions
BMR is what your body burns doing nothing: lying still, keeping your organs going. TDEE is your total burn for the day: BMR plus movement, exercise, and digestion. You lose or gain weight relative to TDEE, which is why it’s the number that matters for planning what to eat.
The adjustment here follows the same system as my calorie calculator: about 15% lower untreated, 10% on T4-only medication with symptoms, 7% on combination therapy with symptoms, 3% treated and optimal, and 18% after thyroidectomy, plus smaller reductions for menopause, years of crash dieting, and a long plateau. Optimized treatment brings most of it back, which is exactly why fixing your thyroid comes before fighting your calories.
Modestly below, never drastically. Aggressive cuts push your body to slow conversion of T4 into active T3, which lowers your burn further and stalls you. A 300 to 500 calorie deficit from the honest number, plus protein and strength work to protect muscle, beats every crash approach.
Mostly, yes. As your levels are restored, your resting burn recovers toward what the standard formula predicts. That’s why re-running this calculator after a dose change is useful: your target moves as your thyroid improves, and it won’t happen without effort on your part in the meantime.
Related Tools
- Hypothyroid Calorie Calculator: turn your TDEE into a daily eating plan
- Thyroid Weight Gain Calculator: how many of your pounds are your thyroid
- Thyroid BMI Calculator: your healthy weight range
- All Thyroid Calculators & Quizzes: the full set of free tools
Scientific References
- al-Adsani H, Hoffer LJ, Silva JE. Resting energy expenditure is sensitive to small dose changes in patients on chronic thyroid hormone replacement. J Clin Endocrinol Metab. 1997;82(4):1118-1125.
- Mullur R, Liu YY, Brent GA. Thyroid hormone regulation of metabolism. Physiol Rev. 2014;94(2):355-382.
- Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241-247.