Adaptive TDEE Spreadsheet
Stop guessing your calories. Calculate your true maintenance calories using your own body's data — not generic formulas that can be off by 10-15%.
What is Adaptive TDEE?
TDEE (Total Daily Energy Expenditure) is the total number of calories your body burns each day. It includes your basal metabolic rate (BMR), digestion, physical activity, and non-exercise activity.
Traditional TDEE calculators use formulas like Mifflin-St Jeor or Harris-Benedict to estimate your calorie burn based on height, weight, age, and activity level. The problem? These formulas can be off by 10-15% for a substantial number of people—and even more for some individuals.
Adaptive TDEE takes a different approach: instead of guessing based on formulas, it calculates your actual TDEE from your own data. By tracking your daily weight and calorie intake over time, the math becomes simple:
TDEE = Average Calories - (Weekly Weight Change × 3,500 / 7)
*3,500 calories ≈ 1 lb of body weight (or 7,700 cal ≈ 1 kg)
After a few weeks of consistent tracking, you'll have a highly personalized TDEE that accounts for your unique metabolism, genetics, muscle mass, and lifestyle —factors that no formula can capture.
Why TDEE Formulas Fall Short
- • Can't account for individual muscle mass
- • Ignore genetic metabolic differences
- • Activity level multipliers are rough guesses
- • Don't adapt to metabolic changes over time
- • Often 10-15% off (200-300+ calories/day)
Why Adaptive TDEE Works Better
- • Uses YOUR actual weight and calorie data
- • Automatically accounts for all metabolic factors
- • Gets more accurate the longer you track
- • Adapts as your metabolism changes
- • Precision improves with every data point
The nSuns (3-Suns) TDEE Method Explained
The nSuns TDEE spreadsheet (also known as the 3-Suns adaptive TDEE spreadsheet) originated from a Reddit user on r/Fitness and r/nSuns subreddits. It quickly became the gold standard for people who wanted a more accurate way to calculate their maintenance calories.
The nSuns method is elegantly simple: instead of trusting a formula that guesses your activity level, you log your daily weight and calorie intake for several weeks. The spreadsheet then uses the relationship between your calorie intake and weight changes to calculate your actual TDEE.
Why the nSuns Spreadsheet Became Popular
- No guessing activity level — Your actual data determines TDEE
- Accounts for metabolic adaptation — Updates as your body changes
- Free and transparent — Open-source with visible formulas
- Community-tested — Refined by thousands of Reddit users
Our calculator above and the downloadable spreadsheet use the same core algorithm as the original nSuns TDEE 3.0 spreadsheet, with some improvements for ease of use.
Adaptive TDEE Calculator
Enter your daily weight and calorie intake below. After 2+ weeks of data, you'll see your personalized TDEE.
Daily Log
Need more data
Enter at least 14 days of weight and calorie data to calculate your adaptive TDEE. Currently you have 0 valid entries.
Download the Adaptive TDEE Spreadsheet
Prefer to track in a spreadsheet? Get our free adaptive TDEE spreadsheet inspired by the popular nSuns/3-Suns method from Reddit.
How to Use the Spreadsheet:
- 1Make a copy of the spreadsheet to your own Google Drive or download
- 2Enter your weight every morning (after bathroom, before eating)
- 3Log your total daily calorie intake accurately
- 4After 2-3 weeks, the spreadsheet will calculate your adaptive TDEE
Spreadsheets Work, But There's an Easier Way
The adaptive TDEE method is powerful, but manually updating a spreadsheet every day gets old fast. That's why we built Zolt.
Spreadsheet Frustrations
- Manual data entry every single day
- Easy to forget and break your streak
- Can't access on-the-go easily
- No notifications or reminders
- Just shows TDEE, not what to eat
- Doesn't sync with health apps
Zolt Makes It Automatic
- Syncs weight from Apple Health / Google Fit
- Automatic TDEE calculation in real-time
- Always in your pocket on your phone
- Smart reminders to log and weigh-in
- Tells you exactly what to eat today
- Tracks macros, workouts, sleep & more
Join thousands who've switched from spreadsheets to Zolt
How Zolt Calculates Your Adaptive TDEE
1. Collects Your Data
Syncs weight from your smart scale and tracks calories from food logging
2. Analyzes Trends
Uses rolling averages and statistical models to filter out daily fluctuations
3. Adapts Continuously
Updates your TDEE in real-time as your metabolism and activity change
Frequently Asked Questions
What is adaptive TDEE?
Adaptive TDEE is a method of calculating your Total Daily Energy Expenditure using your own weight and calorie data over time, rather than relying on generic formulas. It provides a personalized, accurate estimate of how many calories you burn each day.
How long does adaptive TDEE take to be accurate?
Most adaptive TDEE calculations become reasonably accurate after 2-3 weeks of consistent tracking. For highest accuracy, 4+ weeks of daily weight and calorie data is recommended. The more data you provide, the more accurate your TDEE estimate becomes.
Is adaptive TDEE better than TDEE calculators?
Yes, adaptive TDEE is generally more accurate than standard TDEE calculators. Traditional formulas like Mifflin-St Jeor can be 10-15% off for many people because they can't account for individual metabolic variations, muscle mass, genetics, and other factors. Adaptive TDEE uses your actual body data to calculate your true calorie burn.
What is the nSuns TDEE spreadsheet?
The nSuns (also known as 3-Suns) TDEE spreadsheet is a popular adaptive TDEE tracking tool created by a Reddit user. It calculates your TDEE based on your daily weight and calorie intake over time, using the principle that weight change equals calories in minus calories out. It became popular on r/Fitness and r/nSuns subreddits.
Can I use adaptive TDEE while bulking or cutting?
Yes! Adaptive TDEE is perfect for both bulking and cutting phases. In fact, tracking during these phases helps refine your TDEE estimate because you have intentional calorie surpluses or deficits that make the weight change data more meaningful. Just keep tracking consistently.
How accurate is adaptive TDEE?
With 4+ weeks of consistent data, adaptive TDEE can be extremely accurate—often within 50-100 calories of your true TDEE. This is significantly better than formula-based calculators which can be off by 200-400+ calories. The key is consistent, accurate tracking of both weight and calorie intake.
Do I need to track exercise separately?
No! That's the beauty of adaptive TDEE. Since it calculates your calorie burn from actual weight changes, all of your activity (exercise, NEAT, etc.) is automatically factored in. Just track your food and weight consistently.
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Ready to Know Your True TDEE?
Start tracking today with the free calculator above, or download Zolt for the easiest adaptive TDEE experience.