Calorie Deficit to Goal Weight Calculator

Enter your current weight, goal, and daily deficit to see a realistic timeline — including exact goal date, weeks required, and weekly progress chart. Updated January 2026 with latest sustainable guidelines.

Example weight loss progress chart showing steady decline over weeks — Typical steady weight loss curve with consistent deficit (source: NIDDK Body Weight Planner)

Current Weight: Goal Weight (must be lower): (kg)

Quick examples:

Daily Calorie Deficit: Fat Loss Efficiency (%):

90% realistic — accounts for muscle/water loss & metabolic adaptation.

Important: This is an educational estimation tool only — not medical or nutritional advice. Weight loss varies by age, gender, hormones, activity, sleep, stress, and medical conditions. Consult a doctor or registered dietitian before starting any deficit, especially if >750 kcal/day or you have health issues. Aim for 0.5–1% body weight loss per week for safety.

How the Calculator Works (Science-Backed)

1 kg (~2.2 lbs) of body fat ≈ 7700 kcal. We calculate total deficit needed = (weight to lose in kg × 7700) / efficiency %.

Days required = total deficit / daily deficit. Weeks rounded up. Progress shown weekly — daily fluctuations (water, food, hormones) make weekly tracking more reliable.

Realistic efficiency: 85–95% (not 100% — some deficit affects muscle/glycogen). Metabolic adaptation may slow loss over time — reassess every 4–6 weeks.

Sources: Mayo Clinic, NIH, Journal reviews (2025 guidelines emphasize 500 kcal/day for sustainable 0.5–1 kg/week loss).

Calorie Deficit Comparison (2026 Guidelines)

Deficit (kcal/day)	Weekly Loss (approx.)	Speed	Sustainability & Risks
300	0.25–0.35 kg	Very slow	Most sustainable; minimal muscle risk; ideal long-term.
500	0.4–0.6 kg	Recommended	Balanced; preserves muscle with protein + strength training (Mayo Clinic standard).
750	0.6–0.8 kg	Faster	Still safe short-term; monitor energy/hunger.
1000+	0.9–1.2 kg	Aggressive	Higher muscle loss, fatigue, nutrient risk; only under supervision; not for >8–12 weeks.

Best practice: Start at 500 kcal. Never drop below 1200–1500 kcal total intake (women/men) to avoid nutrient deficiencies.

Example: 85 kg → 75 kg with 500 kcal Deficit

Weight to lose: 10 kg (~22 lbs)
Total deficit needed: ~77,000–85,000 kcal (at 90% efficiency)
Time: ~22–24 weeks (~5–6 months)
Weekly loss: ~0.45 kg
Goal date: around July 2026 if starting mid-January.

Use the tool above to simulate your numbers!

Tips for Sustainable Success

Weigh weekly (same conditions) — ignore daily swings.
Prioritize protein (1.6–2.2 g/kg body weight) + resistance training 3×/week to spare muscle.
Track intake accurately (apps like MyFitnessPal).
Re-calculate TDEE every 5–10 kg lost — metabolism adapts ~5–15%.
Include diet breaks (maintenance calories 1–2 weeks) if stalled.
Sleep 7–9 h, manage stress — both affect hunger hormones.

Pair with our Protein Calculator or TDEE Calculator for better accuracy.

Frequently Asked Questions

Why isn't weight loss perfectly linear?

Early weeks often show faster loss (water/glycogen). Later, metabolic adaptation (5–15% drop in TDEE) and reduced NEAT slow progress. Weekly averages smooth this out.

Is a bigger deficit better for faster results?

No — deficits >750–1000 kcal/day increase muscle loss, fatigue, nutrient gaps, and rebound risk. Sustainable 500 kcal/day yields better long-term adherence (Healthline/Mayo Clinic 2025–2026).

What if I hit a weight loss plateau?

Recalculate needs (weight down = lower TDEE). Increase steps/protein, add refeed days, or take 1–2 week maintenance break. Avoid slashing calories further.

Does this include exercise calories?

No — deficit is net below maintenance. Add exercise to increase total burn (e.g., +300 kcal workout allows larger food intake while keeping deficit).

How accurate is the 7700 kcal per kg rule?

It's a good average (from NIH studies), but real value varies 7000–8000 kcal/kg depending on body composition. Efficiency adjustment makes it more realistic.

Can women use this during menopause?

Yes, but expect slower loss due to hormonal changes. Focus on 300–500 kcal deficit + strength training. Consult doctor for thyroid/hormone check.

What if goal is muscle gain while losing fat?

Use smaller deficit (200–400 kcal) or recomp approach (maintenance + high protein + lifting). Timeline will be longer/slower.

Is very low calorie safe long-term?

No — <1200 kcal/day for women or <1500 for men risks nutrient deficiencies, gallstones, hair loss. Use aggressive deficits <8–12 weeks max.

Reviewed by Nutrition & Fitness Contributor • Updated January 2026
Sources: Mayo Clinic Diet, NIH Body Weight Planner, Healthline, PMC reviews on sustainable deficits.

Next Steps to Reach Your Goal

Calculate your TDEE first for accurate deficit.
Track progress weekly + adjust every month.
Share your timeline: