How to Use Our TDEE Calculator for Calorie Planning
Your Total Daily Energy Expenditure (TDEE) is the number of calories you burn each day at your current activity level. Use a TDEE calculator to find this baseline, then adjust it up or down depending on whether you want to lose weight, gain muscle, or maintain where you are. This guide walks you through using our TDEE calculator to get accurate results and understand what they mean for your calorie planning.
What Is TDEE and Why Calculate It?
TDEE stands for Total Daily Energy Expenditure. It's the total amount of energy (measured in calories) your body burns in a day, accounting for everything from keeping your heart beating to exercising.
Your body burns calories in three main ways:
- Basal Metabolic Rate (BMR) — the calories you'd burn if you stayed in bed all day. This is the biggest chunk (typically 60–75% of total daily burn).
- Activity — exercise, sports, or structured movement you do intentionally.
- NEAT (Non-Exercise Activity Thermogenesis) — fidgeting, walking around, existing. This is underrated.
The NHS physical activity guidelines for adults recommend building activity into every day, and understanding your TDEE is the first step to translating that into an actual calorie target.
Our calculator uses the Mifflin-St Jeor equation, which estimates BMR from your age, height, weight, and sex, then multiplies by an activity factor. It's the most accurate formula for the general population.
How to Use the TDEE Calculator: Step-by-Step
Head to our TDEE calculator. You'll need five pieces of information:
1. Your age, height, and weight These are the foundation. Enter your age in years, height in cm, and weight in kg. You can use your weight right now — you don't need to guess your "goal weight." The calculator works with where you are today.
2. Your biological sex The Mifflin-St Jeor formula includes separate coefficients for men and women, so this matters. (If you're non-binary or prefer not to answer, use the value that feels right for you — the formula is just an approximation anyway.)
3. Your typical activity level This is the most important number to get right, because it has the biggest effect on the result. The calculator gives you options:
- Sedentary (little or no exercise) — multiply BMR by 1.2
- Lightly active (light exercise 1–3 days/week) — multiply by 1.375
- Moderately active (moderate exercise 3–5 days/week) — multiply by 1.55
- Very active (hard exercise 6–7 days/week) — multiply by 1.725
- Extremely active (physical job or training twice a day) — multiply by 1.9
The activity level is the trickiest one to self-assess. Most people overestimate. A 30-minute gym session is "activity," but if you spend the other 23.5 hours sitting, you're still lightly active at best. The NHS Better Health guidelines recommend 150 minutes of moderate activity per week for adults; if you're doing that consistently, you're moderately active.
4. Hit calculate The calculator shows you your BMR (the baseline) and your TDEE (the total). That's it.
Interpreting Your Results
Your TDEE is now your baseline calorie expenditure. For example:
Scenario: A 32-year-old woman, 1.70m tall, 70kg, moderately active
- BMR: ~1,400 calories/day
- Activity multiplier: 1.55
- TDEE: ~2,170 calories/day
This means if she eats 2,170 calories per day and maintains her current activity level, her weight stays stable. This is her maintenance intake.
The NHS understanding calories page explains the energy balance model: calories in vs. calories out. To lose weight, you eat less than your TDEE. To gain, you eat more.
TDEE for Different Goals: Weight Loss, Maintenance, and Gain
Now that you know your TDEE, here's how to use it for specific goals.
For weight loss
Create a calorie deficit. The NHS Better Health weight-loss plan suggests a deficit of around 500–600 kcal/day, which produces roughly 0.5–1 kg of weight loss per week. So if your TDEE is 2,170, aim for 1,570–1,670 calories per day.
For more detail on structuring a deficit, see our guide on how to use our calorie deficit calculator. It walks through the same logic but focuses specifically on the maths of deficit targets.
For maintenance
Eat at your TDEE. This is straightforward in theory; the tricky part is tracking accurately (because portion size estimates are often off by 20–30%).
For weight gain (muscle)
Eat in a calorie surplus. A modest surplus of 300–500 kcal/day above TDEE, combined with strength training, typically leads to muscle gain rather than just fat. (Eating a massive surplus just leads to fat gain, which is why "bulking" has a bit of a reputation.)
Common Mistakes When Using Your TDEE
Mistake 1: Overestimating activity level
Most people are more sedentary than they think. If you're not breaking a sweat or breathing hard for at least 30 minutes, you're not in "very active" territory. When in doubt, pick the lower category.
Mistake 2: Treating TDEE as fixed
TDEE changes as you lose or gain weight, age, or change your activity level. Recalculate every few months or whenever your circumstances shift significantly.
Mistake 3: Ignoring non-exercise activity
NEAT — the calories you burn from daily living — can be 15–30% of your total expenditure. If you go from a standing job to a desk job, your TDEE drops noticeably, even without changing formal exercise.
Mistake 4: Not accounting for the adaptive response
Your body isn't a simple machine. When you eat in a large deficit, your metabolic rate sometimes drops slightly as your body conserves energy. This is why very aggressive deficits often plateau faster than the maths predicts. Aim for 500–600 kcal deficit, not 1,000+.
Mistake 5: Forgetting the linked tools
Your TDEE is one number in a larger system. Use it alongside our ideal weight calculator to understand what weight range is healthy for your height. Pair it with our water intake calculator to make sure you're hydrating appropriately for your activity level.
Frequently Asked Questions
Q: Is TDEE the same as BMR?
No. BMR is the calories you burn at rest. TDEE is BMR multiplied by your activity level. For the woman in the example above, BMR is 1,400; TDEE is 2,170. The difference (770 calories) is what she burns from activity and daily living.
Q: How accurate is the TDEE calculator?
The Mifflin-St Jeor formula is accurate within ±10–20% for most people. Your actual TDEE might be 10% higher or lower depending on factors the formula can't account for (metabolism, digestion, genetics). Use the result as a starting point, not gospel. Track your weight for 2–3 weeks at your calculated TDEE; if you're losing or gaining, adjust your intake by 100–150 calories and track again.
Q: What if my weight is changing?
Recalculate your TDEE every time you lose or gain 5–7 kg. Your BMR scales with your weight, so the number gets smaller as you lose weight (which is why weight loss often slows as you get closer to your goal).
Q: Can I use TDEE if I have a medical condition?
The TDEE formula is designed for otherwise healthy adults. If you have thyroid issues, PCOS, diabetes, or other conditions that affect metabolism, use the TDEE as a rough starting point and work with a GP or registered dietitian to refine it. Your actual expenditure might differ significantly from the formula.
Q: Should I eat below my TDEE every day?
Consistency matters more than precision. If your TDEE is 2,170, aiming for 1,670 on average is fine — it's okay if Monday is 1,600 and Tuesday is 1,750. The weekly total is what drives weight loss, not the daily number.
Q: How do I know if my activity level selection is right?
Track your weight for 2–3 weeks at your calculated TDEE without changing what you eat. If your weight is stable (within 0.5 kg), you got the activity level right. If you're losing weight, your actual TDEE is lower — either you're more sedentary than you thought, or your metabolism is on the lower end of average. If you're gaining, the opposite is true.
Q: Can I use the TDEE calculator for different goals?
Yes. Calculate once to find your TDEE, then apply different targets: your TDEE for maintenance, TDEE minus 500 for weight loss, TDEE plus 300 for muscle gain. You only need one calculator run; the maths changes based on your goal.
Now that you understand your TDEE and how to use it, start tracking. Use our TDEE calculator to get your baseline, then pick your goal (loss, maintenance, or gain) and commit to it for at least 2–3 weeks. Weight fluctuates daily from water and digestion, so track weekly averages, not daily numbers.
For more on calorie planning, see our guide on how to use our calorie deficit calculator if you're focused on weight loss, or check out how to use our water intake calculator to make sure you're supporting your body's recovery.