Updated · Built and checked by the PlinzoTools team, formulas tested against published sources
Estimate how many weeks it'll take to reach a goal weight at a given calorie deficit.
20.0 weeks
Where the Calorie Deficit Calculator solves for a daily calorie target given a desired weekly rate, this tool solves for time: given your current weight, goal weight, and a daily calorie deficit, it estimates how many weeks it will take.
Enter your current weight, goal weight, and daily calorie deficit. Estimated weeks to goal appears instantly, along with your implied weekly loss rate.
Weekly Loss (lb) = (Daily Deficit × 7) / 3,500
Weeks to Goal = (Current Weight - Goal Weight) / Weekly Loss
This is a straight-line estimate based on a fixed daily deficit -- real weight loss isn't perfectly linear (water weight, muscle adaptation, and metabolic adjustment all play a role), so treat the estimate as a rough timeline, not a guarantee.
The default inputs are a current weight of 200 lb, a goal of 180 lb, and a 500 kcal daily deficit. The weekly loss is 500 x 7 / 3,500, which equals 1.0 lb per week. The pounds to lose are 20, so the estimate is 20 weeks. If the same person chose a 250 kcal deficit instead, weekly loss falls to 0.5 lb and the estimate doubles to 40 weeks. Halving the deficit doubles the time, because the two are inversely proportional in this model.
500 x 7 = 3,500 kcal per week, / 3,500 = 1.0 lb per week. 20 lb / 1.0 = 20 weeks.
The deficit is the gap between what you eat and what you burn. Many people estimate their maintenance calories with a TDEE calculator and then subtract the deficit they intend to run. If you are unsure of your maintenance level, an over-optimistic deficit will make the timeline look shorter than reality. The most reliable approach is to log your weight and intake for a few weeks and see what deficit your actual results imply.
Try several deficits and compare timelines instead of fixating on one. A modest deficit that you can maintain often beats an aggressive one that you abandon. Recalculate every few weeks using your updated weight and the deficit you have actually achieved. Very low calorie intakes should be discussed with a doctor or registered dietitian, particularly if you have a medical condition, are pregnant or breastfeeding, or take medication. This tool is educational and does not replace medical advice.
Weight loss isn't perfectly linear -- water retention, metabolic adaptation, and how consistently the deficit is actually maintained all affect the real timeline.
Not necessarily -- a larger deficit increases the risk of muscle loss and is harder to sustain; see the Calorie Deficit Calculator's safe-minimum guidance.
This tool is for weight loss -- if your goal is to gain weight, use the Calorie Surplus Calculator instead.
No result is shown, since the tool requires the goal to be at or below the current weight. Use a calorie surplus tool for weight gain.
It roughly halves it in this model, because weeks are pounds to lose divided by weekly loss. Real-world results are usually less clean.
Yes. Enter your new current weight and the deficit you are actually achieving, since energy needs typically decrease as body weight falls.
The tool is set up for pounds. Convert kilograms to pounds first by multiplying by 2.2046.
Reference: Centers for Disease Control and Prevention