Daily calorie target: {{ format(dailyCalories) }} kcal
(TDEE {{ format(tdee) }} − deficit {{ format(deficit) }})
You need an average deficit of {{ format(deficit) }} kcal / day to lose {{ format(totalLoss) }} {{ weightUnit }} in {{ timeframeValue }} {{ timeframeUnit }}.
Target weekly loss: {{ format(weeklyLoss) }} {{ weightUnit }}
| Week | Weight ({{ weightUnit }}) | Loss-to-date | TDEE | Cal Target |
|---|---|---|---|---|
| {{ r.week }} | {{ formatDec(r.weight) }} | {{ formatDec(r.loss) }} | {{ format(r.tdee) }} | {{ format(r.cal) }} |
Energy balance governs body-mass change: you maintain weight when intake equals expenditure and lose it when consistent daily calories fall short of what the body uses for basic functions and movement. Basal metabolic rate, activity level, purposeful exercise, and non-exercise thermogenesis therefore determine how rapidly fat stores adjust over time.
The calculator models these relationships to estimate a personalised daily calorie target that bridges your present weight and desired goal within a chosen timeframe. By combining a physiological equation for resting energy with an activity multiplier, it establishes total expenditure, then subtracts the deficit needed to meet weekly loss milestones.
Use it when crafting a structured eating plan: enter your age, sex, height, weights, activity, and deadline to receive an actionable intake number, progressive trend chart, and downloadable week-by-week schedule that clarifies expected losses. Always consult a qualified professional before making major dietary changes—this calculator offers informational estimates, not medical advice.
Resting energy expenditure accounts for roughly sixty percent of daily caloric use and is chiefly a function of fat-free mass, height, sex, and age. The Mifflin-St Jeor equation provides a research-validated estimate of that baseline. Multiplying the baseline by an empirically derived activity factor approximates total daily energy expenditure. Fat loss then follows the first law of thermodynamics: energy cannot be created, only transformed, so a sustained intake deficit mobilises stored triacylglycerol, releasing heat and carbon dioxide.
The tool applies linear pacing—weight decreases evenly each week—because short intervals minimise the widening gap between initial and updated expenditure. On each recompute it regenerates a schedule, updates interactive charts through a charting layer, and maintains state by a reactive engine, all entirely within the browser session.
| Symbol | Meaning | Unit | Typical Range | Sensitivity |
|---|---|---|---|---|
| W | Current body mass | kg | 45 – 200 | High |
| H | Stature | cm | 140 – 210 | Moderate |
| A | Age | years | 18 – 80 | Moderate |
| S | Sex constant | kcal | −161 or 5 | Low |
| F | Activity factor | — | 1.2 – 1.9 | High |
BMR = 10×80 + 6.25×175 − 5×30 + 5 = 1 784 kcal
TDEE = 1 784 × 1.55 ≈ 2 766 kcal
Goal 70 kg in 12 weeks ⇒ weekly loss ≈ 0.83 kg
Daily deficit = 0.83 × 7 700 / 7 ≈ 912 kcal
Daily calorie target = 2 766 − 912 ≈ 1 854 kcal
Computation is O(n) with n = weeks in the plan; modern browsers solve hundreds of weeks instantly. IEEE-754 double precision keeps rounding error below 0.1 %. Rendering updates rely on a reactive engine; charting uses a canvas-based layer. No data leaves the device, supporting strict privacy requirements.
Follow this sequence to generate a safe, time-bound calorie plan.
Estimates follow peer-reviewed formulas and standard activity multipliers, yet individual metabolic rates can differ by 10 – 15 %. Treat numbers as starting guidance, not absolute limits.
No. All calculations run locally and disappear when you close the page; nothing is sent to any server or analytics platform.
Larger deficits increase fatigue and muscle-loss risk. Many guidelines advise limiting weekly loss to one percent of body mass for sustained, healthy progress.
Select the factor that mirrors an average week. If you walk under 5 000 steps daily and rarely exercise, pick Sedentary; reserve higher factors for regular structured training.
The schedule recalculates BMR as weight drops. Lower mass burns fewer calories, so the required deficit shrinks unless you adjust intake or increase activity.