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Weight Loss Calculator

Enter where you are, where you want to be, and by when — get a safety-checked plan with an visual projection.

Updated July 2026Interactive guided tool

Goal must be below current weight, both 30–300 kg, timeframe 1–104 weeks.

🧮 FitCalcly — Weight Loss Calculator • fitcalcly.com • free, evidence-based health tools

Weekly rate

Daily deficit needed

Result guide

Your weight-loss plan summary

Use the projected rate as a safety check and planning guide. Real loss is rarely linear because water, glycogen, digestion and adherence change week to week.

Calculate your result to connect the guidance below with your numbers.

✓ What makes the plan sustainable

Create a modest repeatable deficitBase meals on protein, vegetables, fruit, pulses and measured energy-dense foods.
Keep resistance trainingTwo or more weekly sessions help preserve strength and lean mass during loss.
Raise daily movementSteps and walking add expenditure without the recovery cost of hard exercise every day.
Review the trend, not one weigh-inUse a weekly average and adjust only after enough consistent data.

△ Signals the plan is too aggressive

Persistent dizziness or exhaustionThese can indicate that intake, hydration or recovery is inadequate.
Frequent binge-restrict cyclesA plan that repeatedly triggers loss of control is not sustainable and deserves support.
Rapid strength and performance declineThis may suggest too large a deficit or poor protein and carbohydrate intake.
Special medical situationsPregnancy, adolescence, eating-disorder history and chronic disease need supervised planning.
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How the plan is built

One kilogram of body fat stores roughly 7,700 kcal. The calculator divides your total loss across your timeframe to get a weekly rate, converts that into the daily calorie deficit required, and — if you enter your TDEE — shows the actual daily intake to aim for. The interactive chart traces your projected path from today to goal day.

What a safe rate looks like

0.25–0.5 kg per week (a 250–550 kcal daily deficit) is the sustainable sweet spot for most people. 0.5–1 kg/week works for higher starting weights or short phases but demands high protein and strength training to protect muscle. Above 1 kg/week reliably costs muscle, energy and adherence — the calculator will flag it and suggest a longer timeframe instead.

Why the line won't be straight in real life

Expect a fast first week (water and glycogen, not fat), plateaus every few weeks, and daily fluctuations of ±1 kg from salt, carbs and hydration. Judge progress on the weekly average, not any single morning. And as you lose, your TDEE falls — recalculate every 4–5 kg and adjust the deficit.

The three levers that protect results

Protein at 1.6–2.2 g/kg preserves muscle in a deficit; resistance training 2–4× weekly tells the body to burn fat rather than muscle; and 7+ hours of sleep keeps hunger hormones workable. Get your maintenance number from the TDEE calculator, then split intake with the macro calculator and structure it with the meal plan calculator.

Practical guide for using this result

Reading the projection

The line assumes a steady average deficit, but scale weight may pause or jump because water changes mask tissue loss.

How to adjust

If the four-week trend is slower than intended and tracking is consistent, make a small change to portions or movement rather than a drastic cut.

Maintenance matters

Plan how meals, activity and self-monitoring will continue after the goal so weight regain is less likely.

How to evaluate a weight-loss projection

The chart assumes an average energy deficit, while real weight change is not perfectly linear. Water and glycogen can move the scale before fat loss is visible.

Use the projection as a range

Treat the date as an approximate window. Plateaus, travel, illness and changes in activity can shift the timeline.

Protect lean mass and wellbeing

Use adequate protein, resistance training, sleep and a moderate deficit. Faster is not automatically better when strength, mood or adherence deteriorates.

Adjust from trends, not frustration

Review two to four weeks of average weight and waist change before modifying calories. A small sustainable adjustment is easier to evaluate than a dramatic cut.

Sources & references

  1. Hall KD, et al. Quantification of the effect of energy imbalance on bodyweight. Lancet. 2011;378(9793):826–837.
  2. Wing RR, Phelan S. Long-term weight loss maintenance. Am J Clin Nutr. 2005;82(1 Suppl):222S–225S.
  3. Helms ER, et al. Evidence-based recommendations for natural bodybuilding contest preparation. J Int Soc Sports Nutr. 2014;11:20.

Frequently asked questions

How many calories equal 1 kg of fat?
Roughly 7,700 kcal. A 500 kcal daily deficit therefore projects to about 0.45 kg per week — the classic sustainable pace.
Why did I lose fast in week one then slow down?
Early loss is mostly water and stored glycogen. Fat loss settles into the projected rate afterwards — that slowdown is normal, not failure.
Is losing 1 kg per week safe?
For higher starting weights and short phases it can be workable with high protein and training, but for most people it costs muscle and adherence. 0.25–0.5 kg per week wins long-term far more often.
Should I eat back exercise calories?
No — if your TDEE already includes your activity level, adding workout calories double-counts them. Recalculate TDEE only when your routine genuinely changes.
Why did my weight stop changing for a week?
Short plateaus are common because water, sodium, bowel contents and menstrual-cycle changes can offset fat loss on the scale.
How fast is too fast?
A rate that causes persistent fatigue, poor training, significant hunger or other symptoms is too aggressive for you even if a formula allows it.
Why is my weekly loss different from the projection?
The calculator models energy balance, but scale weight also reflects water, sodium, carbohydrate, menstrual cycle and digestion. Compare several weekly averages before deciding the plan is off track.