How to calculate your TDEE and set a deficit
TDEE (Total Daily Energy Expenditure) is the number of calories you burn in a day at your current activity level. A calorie deficit means eating less than your TDEE — the gap between your calories consumed and TDEE is your deficit.
Mifflin-St Jeor equation (most accurate formula)
The formula gives you a starting TDEE estimate. It's not perfect — individual metabolic rates vary by ±10–15% — but it's the right starting point. All calorie tracking apps use some variant of this formula.
TDEE = 1,533 × 1.55 = 2,377 cal/day
500 cal/day deficit → eat 1,877 cal/day → lose ~0.5kg/week
How big should your calorie deficit be?
| Deficit size | Weekly loss | Best for | Risk |
|---|---|---|---|
| 200–300 cal/day | ~0.2kg/week | Athletes, muscle preservation, maintenance phase | Slow — may lose motivation |
| 400–500 cal/day | ~0.4–0.5kg/week | Most people — sustainable, minimal muscle loss | Low — the standard recommendation |
| 500–750 cal/day | ~0.5–0.7kg/week | Accelerated fat loss, BMI over 27 | Moderate — hunger increases, track protein carefully |
| 750–1,000 cal/day | ~0.7–1kg/week | Under medical supervision, significant obesity | High — muscle loss risk, nutrient deficiency risk |
The 500 cal/day deficit → 0.5kg/week loss figure is the most cited and generally the safest sustained deficit for most people. Below 1,200 cal/day (women) or 1,500 cal/day (men) is considered a very low calorie diet and should only be pursued with medical guidance.
Top 5 calorie deficit calculator apps 2026
NutriBalance
NutriBalance calculates your TDEE on setup using the Mifflin-St Jeor formula and sets a daily calorie goal based on your deficit target. From that point, every food you log is deducted from your daily budget in real time — you see your remaining calories and macros at a glance throughout the day.
What makes it particularly effective for deficit tracking is the streak system. Staying in a deficit every day for 30 days is the hard part, not the calculation. A tracked streak — where breaking it means your character deteriorates — provides a psychological anchor that static calorie budgets don't. The home screen widget shows your remaining calories without opening the app, removing the friction that causes people to skip logging.
- Full macro tracking free — not just calories
- Real-time remaining calories and macro display
- Streak system maintains daily deficit consistency
- Android widget for at-a-glance calorie budget
- 7M+ food database, fast barcode scanner
- Custom calorie targets — set exact deficit
- TDEE estimate is static (not adaptive)
- No exercise calorie adjustment built-in
- No micronutrient tracking
MacroFactor
MacroFactor is the only app that updates your deficit target based on real data. After 2–3 weeks of logging, it analyses your actual weight changes against your logged calories and recalculates your true TDEE. This matters because static TDEE estimates (all other apps) can be off by 200–400 cal/day, causing plateaus that confuse people into thinking their diet stopped working.
If you've been stuck at a plateau for more than 3 weeks despite maintaining a deficit, MacroFactor's adaptive approach is likely to break it. The trade-off is no free tier at $11.99/month — meaningful cost for a tracking tool.
- Adaptive TDEE — recalculates based on real data
- Best for breaking plateaus
- Evidence-based algorithm (peer-reviewed methodology)
- No free tier
- Requires consistent weight logging for algorithm to work
- Most expensive option here
Lose It!
Lose It! was designed specifically for weight loss and the calorie deficit workflow is central to the app. The free tier includes basic calorie and macro tracking with a clear daily budget display. The onboarding sets your goal weight and timeline, then calculates the required daily deficit automatically — a smoother experience than apps that require you to set calories manually.
Nothing exceptional stands out, but it covers the core deficit tracking use case competently at a lower price point than premium competitors.
- Goal-based onboarding — sets deficit automatically
- Basic macros in free tier
- Clean weight loss focused UI
- Static TDEE estimate
- No habit or streak features
MyFitnessPal
MFP calculates a TDEE-based goal on setup and shows your daily calorie budget. The calorie deficit tracking works well if you're a Premium subscriber. The free tier, however, only shows calories — not protein, carbs, or fat — which makes it inadequate for anyone who cares about maintaining protein during a deficit (which you should: higher protein preserves lean mass during fat loss).
- Best food database for finding restaurant/branded foods
- Exercise calorie adjustment built-in
- Macros require £15.99/month
- Expensive for deficit tracking only
TDEE Calculator websites (TDEEcalculator.net, etc.)
Standalone TDEE calculator websites aren't apps, but they deserve mention. If you just want to calculate your TDEE and set a manual calorie goal, these sites run the Mifflin-St Jeor or Harris-Benedict formula clearly and transparently. You can then take that number and plug it into any calorie tracking app. Good for a one-time calculation if you want to understand exactly how your target was derived.
- Transparent formula — you see the calculation
- No account required
- No daily tracking — just a one-time calculator
- Need a separate app for actual deficit tracking
Verdict
Best free deficit tracker: NutriBalance — sets TDEE-based target, shows real-time remaining calories, full macros free, streak system for daily consistency.
Best if you've hit a plateau: MacroFactor — adaptive algorithm adjusts your target based on actual data. Worth the cost if static estimates have stopped working.
Best for goal-based onboarding: Lose It! — calculates the required deficit automatically from your goal weight and timeline.
Tips for accurately tracking a calorie deficit
1. Weigh food, don't estimate
The single biggest source of deficit tracking error is estimating portion sizes by eye. Research shows people underestimate their intake by an average of 20–40%. A digital kitchen scale costs under £15 and is the highest-ROI investment for serious deficit tracking.
2. Log everything, including cooking oils and condiments
A tablespoon of olive oil is 120 calories. A tablespoon of peanut butter is 90 calories. These add up to 300–500 calories per day of unlogged "phantom" intake that explains why a 500 cal/day deficit produces less than expected weight loss.
3. Don't adjust for exercise calories (unless you're very active)
Most apps offer to "eat back" exercise calories — reducing your deficit by the calories burned in a workout. For most people this is counterproductive. Exercise calorie estimates (even from fitness trackers) are notoriously inaccurate, often overestimating by 30–50%. Build exercise into your activity multiplier when you calculate TDEE, then ignore it during daily tracking.
4. Use weekly averages, not daily
Weight fluctuates by 1–2kg day to day based on water retention, sodium, digestion, and hormones. Checking your weight daily and panicking about single-day variance is the primary cause of deficit-tracking abandonment. Weigh yourself at the same time every morning for 7 days and track the weekly average — that number is meaningful. Single-day numbers aren't.
Track your deficit — completely free
NutriBalance sets your TDEE-based calorie target on setup and tracks your remaining calories in real time. Full macro tracking included at no cost.
Download Free on Android →FAQ
NutriBalance, MyFitnessPal, Lose It!, and most calorie tracking apps calculate your TDEE automatically on setup using age, weight, height, and activity level. They then set a daily calorie target based on your weight loss rate goal. You don't need to do the calculation manually — just enter your details and the app sets a target deficit for you.
TDEE formulas based on Mifflin-St Jeor are accurate to ±10–15% for most people. This means a calculated TDEE of 2,000 cal/day could be off by 200–300 calories in either direction. This is why MacroFactor's adaptive approach (which learns your actual TDEE from real data) produces more accurate targets than static formulas over time. For most users, the Mifflin-St Jeor estimate is close enough to start with — adjust after 3–4 weeks based on actual weight change.
Yes, a 500 cal/day deficit is the standard recommendation for most healthy adults. It produces approximately 0.5kg (1lb) of fat loss per week and is generally sustainable without significant muscle loss, provided protein intake is adequate (1.6–2.2g/kg bodyweight). Deficits larger than 750 cal/day increase muscle loss risk and require careful protein tracking. Deficits below 1,200 cal/day (women) or 1,500 cal/day (men) require medical supervision.
Three most common causes: (1) underestimating food intake — switch from visual estimation to weighing food on a scale; (2) adaptive thermogenesis reducing your effective TDEE — try reducing target by 100–150 cal; (3) water retention masking fat loss — check weekly weight averages rather than daily. If you've been tracking accurately for 3+ weeks with no trend change, the TDEE estimate is likely off — try MacroFactor's adaptive algorithm or manually reduce your target by 10%.
Related guides: Complete calorie deficit guide · How to track macros for weight loss · Best calorie deficit apps for Android