Weight Loss Simulator
Free weight loss simulator: estimate the time to a lower target weight from your daily calorie intake and activity level, with a constant estimated TDEE.
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Free weight loss simulator: estimate the time to a lower target weight from your daily calorie intake and activity level, with a constant estimated TDEE.
How to read your result
The target date and weeks required come from a constant daily calorie deficit. The weekly weight-loss value is also an estimate, not a guarantee. This page shows numerical results rather than a weight-trajectory chart. A weight-loss projection requires a target below current weight and calorie intake below estimated TDEE; a non-positive deficit cannot predict reaching a lower weight.
How to use this weight simulator
Select your sex, then enter age, height, current weight, target weight and planned daily calorie intake. Choose your activity level and use the displayed metric or imperial units. Press Calculate to see estimated TDEE, daily calorie deficit, weekly weight change, weeks required and a target date. Enter calorie intake, not the deficit: the tool calculates the deficit from TDEE. After changing inputs, press Calculate again to update the result.
The science behind the projection
The tool estimates BMR with the Mifflin-St Jeor equation and applies the selected activity factor to estimate TDEE. Daily deficit is TDEE minus planned calorie intake. Estimated kilograms lost per day are the deficit divided by 7700, and time to goal is weight to lose divided by that daily estimate. It holds TDEE constant for the projection; it does not automatically model declining energy expenditure as body weight changes.
Limits and practical tips
Actual weight change is affected by water balance, adherence and changes in energy expenditure. Recalculate with updated measurements rather than treating the initial date as a promise. The formula does not model water loss, muscle change or metabolic adaptation. Use the TDEE and Calorie Deficit tools to understand the inputs, and discuss an appropriate weight-management plan with a qualified professional if you need individual advice.
Frequently Asked Questions
- How long does it take to lose 10 kg?
- At a safe ~0.5 kg/week pace, about 20 weeks. A larger deficit is faster but harder to sustain and risks muscle loss.
- Is fast weight loss safe?
- Losing more than ~1 kg per week often means muscle and water loss and a higher rebound risk. Slower loss is more sustainable.
- Why does weight loss slow down over time?
- As you lose weight your TDEE drops, so the same intake becomes a smaller deficit. Recalculate your target as you progress.
- Can I see what my body will look like after losing weight?
- Yes — pair this simulator with CaloNote's free 3D Body Visualizer. Enter your target weight and body fat percentage there to preview your shape after weight loss, then use the goal date from this tool to plan the timeline.
- Is this weight loss simulator free?
- Yes. It is free, requires no sign-up, works on mobile and supports kg and lb. The projection uses a constant estimated TDEE and daily calorie deficit; it does not model an adaptive curve as your weight changes.