⚠️ Educational tool — not medical advice
BMI Weight Loss Calculator
How long will it take to reach your goal? Enter your height, current weight, and either a target weight or a BMI target plus a timeframe in weeks. The calculator computes the daily calorie deficit you would need, projects each week, estimates your TDEE for context, and flags plans that cross safety thresholds.
How this tool helps: it turns “I want to lose 10 kg” into concrete numbers — daily deficit, weekly pace, projected timeline, and safety warnings. It does not diagnose you, and it cannot replace a doctor or dietitian.
Your numbers
Your weight-loss plan
—
BMI now → target
—
kg to lose
—
kg per week
Daily calorie deficit needed: — kcal/day
—
Estimated TDEE (kcal/day)
—
Daily intake target (kcal)
—
Total deficit (kcal)
Weekly projection
| Week | Projected weight (kg) | Cumulative loss (kg) |
|---|
Try an example
How it works
- BMI = weight (kg) ÷ height² (m).
- Total deficit = kilograms to lose × 7,700 kcal — the commonly used energy equivalent of one kilogram of body weight.
- Daily deficit = total deficit ÷ (weeks × 7).
- Safety flags: daily deficit above 1,000 kcal → danger; pace above 1 kg/week → not recommended; target BMI below 18.5 → danger (underweight); intake below ~1,200 kcal (women) / 1,500 kcal (men) → warning.
- TDEE uses the Mifflin-St Jeor equation × an activity factor, for context only.
- Projections are linear estimates. Real weight loss slows over time (metabolic adaptation, water shifts) — treat the timeline as a guide, not a promise.
Scope boundary. This tool plans a calorie deficit toward a BMI/weight goal over a timeline. It does not estimate body fat percentage (see our body fat calculator), it does not compare multiple TDEE formulas (see our TDEE calculator), and for a plain BMI number see our BMI calculator.
Frequently asked questions
How long does it take to lose 10 kg?
It depends on your daily calorie deficit. One kilogram of body weight is roughly 7,700 kcal, so losing 10 kg requires a total deficit of about 77,000 kcal. At a steady deficit of 500 kcal per day that is about 22 weeks; at 750 kcal per day about 15 weeks. Deficits above 1,000 kcal per day are not recommended without professional supervision.
How many calories do I need to cut to lose 1 kg per week?
About 1,100 kcal per day: 1 kg equals roughly 7,700 kcal, divided by 7 days. Note that 1 kg per week is the upper limit most health guidelines consider, and a 1,100 kcal daily deficit exceeds the 1,000 kcal caution threshold, so a slower pace is usually the safer plan.
Is a 1000 calorie deficit safe?
A deficit of 1,000 kcal per day is a common caution threshold used by this calculator. Larger deficits raise the risk of muscle loss, nutrient gaps, fatigue, and rebound. Anyone planning an aggressive deficit should consult a doctor or registered dietitian first, especially with existing health conditions.
What is the maximum safe weight loss per week?
Most health authorities cite around 0.5 to 1 kg per week as a reasonable range for most adults. This calculator warns when your plan exceeds 1 kg per week and flags the plan as not recommended.
Why does this calculator use 7700 calories per kilogram?
The 7,700 kcal per kilogram figure is the widely used energy equivalent of body weight change. It is an approximation: real bodies also lose water and lean tissue, and metabolic adaptation slows progress, so treat projections as estimates, not guarantees.
Is this calculator medical advice?
No. This tool is for education only. BMI and calorie math cannot account for medical conditions, medications, pregnancy, or metabolic disorders. Talk to a doctor or registered dietitian before starting a weight-loss plan.
Can I target an underweight BMI with this planner?
The calculator will compute the numbers but flags any target BMI below 18.5 as a danger: that is the underweight threshold and targeting it is not recommended. If body image concerns are involved, consider speaking with a health professional.
How does TDEE relate to my calorie deficit?
TDEE (total daily energy expenditure) is estimated here with the Mifflin-St Jeor equation times an activity factor. Your daily intake target equals TDEE minus your deficit. If that intake falls below about 1,200 kcal for women or 1,500 kcal for men, the calculator raises a warning.
Health disclaimer. This calculator is an educational tool, not medical advice. Safe, sustainable weight loss depends on many individual factors. Consult a doctor or registered dietitian before making significant diet or lifestyle changes.
Free tool by NRTechStudio