I remember when I started tracking protein… and promptly ate 1,800 calories a day while training five times a week. I had the protein right and the energy completely wrong. I lost weight, sure — along with strength, sleep quality and, eventually, the will to train. Nobody had told me that protein is only half the equation. The other half is knowing how much energy you actually burn.
In this article
The TDEE Calorie Calculator above answers that. Enter your sex, age, height, weight and activity level. It estimates your BMR with the Mifflin-St Jeor equation, multiplies it out to your total daily energy expenditure, and gives you three calorie targets — cut, maintain and lean bulk — each with a sensible protein range attached.
What TDEE actually means
TDEE is your Total Daily Energy Expenditure: everything you burn in 24 hours. Most of it is not the gym. The breakdown surprised me when I first saw it:
| Component | What it is | Share of TDEE |
|---|---|---|
| BMR | Keeping you alive: breathing, brain, organs | 60–70% |
| NEAT | Walking, fidgeting, chores, standing | 15–25% |
| Exercise | Planned training sessions | 5–10% |
| TEF | Digesting food (protein costs the most) | ~10% |
That is why two people with the same workouts can need wildly different calories. The warehouse worker out-walks the office worker by thousands of steps before either touches a barbell. The British Nutrition Foundation has a clear explainer on energy balance if you want the science behind the split.
The Mifflin-St Jeor formula
Of the common BMR equations, Mifflin-St Jeor is the one most dietitians I trust default to. For men:
For women, the final constant is −161 instead of +5. Then:
| Variable | What it is | Example |
|---|---|---|
| W | Weight in kilos | 80 kg |
| H | Height in centimetres | 178 cm |
| A | Age in years | 35 |
| Activity multiplier | 1.2 (sedentary) to 1.9 (extra active) | 1.55 |
No formula is perfect — they estimate within a few hundred calories for most people. I treat the result as a starting point, eat at it for two to three weeks, watch the scale, then adjust. The NHS Eat Well guide gives the official UK reference intakes (around 2,500 kcal for men and 2,000 for women) as a sanity check.
A worked example: 80 kilos, 178 cm, 35, moderately active
Let me walk you through my exact setup for a typical reader — a 35-year-old man, 80 kg, 178 cm, training three to four days a week.
| Step | Calculation | Result |
|---|---|---|
| BMR | 10×80 + 6.25×178 − 5×35 + 5 | 1,743 kcal |
| TDEE | 1,743 × 1.55 | 2,701 kcal |
| Cut (−20%) | 2,701 × 0.8 | 2,161 kcal |
| Lean bulk (+10%) | 2,701 × 1.1 | 2,971 kcal |
| Protein range | 80 × 1.6 to 2.2 | 128–176 g |
Notice the cut is only about 540 kcal below maintenance — aggressive enough to lose roughly half a kilo a week, gentle enough to keep training hard. That is the deficit I recommend to everyone who asks me. Bigger deficits mostly just cost you muscle and patience.
Using the TDEE Calorie Calculator step by step
Fill the boxes at the top of this page, then press Calculate.
| Input field | What to enter | Sample figure |
|---|---|---|
| Sex and age | Both shift the BMR estimate | Male, 35 |
| Height | In cm, or inches if you prefer | 175 |
| Weight | In kg, or pounds if you weigh in lb | 75 |
| Activity level | Include your job, not just the gym | Moderately active |
You get your BMR, your TDEE, and three targets — cut, maintain and lean bulk — each paired with a protein gram range for your weight. Everything runs in your browser. Once you have the calorie number, the Macro Split Calculator divides it into protein, fat and carbs, and the Protein Intake Calculator on the home page refines the protein target by goal.
The activity mistake almost everyone makes
When I first used a TDEE calculator, I picked “very active” because I trained hard four days a week. I ignored the other 23 hours: desk job, car commute, sofa evenings. My real life was lightly active at best, and the calculator overestimated me by 400 kcal. I “could not lose weight” for two months on what I thought was a deficit.
Be brutally honest about the multiplier. Training is one hour. Your job is eight. If in doubt, pick one level lower than your ego suggests, run it for three weeks, and adjust from real scale data. The formula gives you a starting line, not a verdict.
Questions I get asked about TDEE and calories
What is a good TDEE calculator for the UK?
Any calculator using the Mifflin-St Jeor equation with honest activity multipliers — like the one on this page. The equation is the same worldwide; what matters for the UK is using kilos, centimetres and realistic activity levels. I would avoid any tool that does not show you its formula or its multipliers.
How accurate is the Mifflin-St Jeor equation?
Reasonably accurate for most adults — usually within 10% of measured values, which is a couple of hundred calories. It is less reliable at very high body fat or very high muscle mass. I treat the number as a starting hypothesis and let two to three weeks of scale weight confirm or correct it.
Should I eat back my exercise calories?
No — that is the classic double-count. Your activity multiplier already includes your training. Adding gym calories on top is how people erase their deficit without realising it. The only exception is a huge endurance day far outside your normal routine.
Why am I not losing weight on my calculated deficit?
Almost always one of three things: the activity level was overstated, the food tracking is optimistic (oils, drinks and snacks are the usual suspects), or you have only been at it for ten days. I give any new target three full weeks before I change it. The scale lies daily and tells the truth weekly.
