Health / Browser tools
Calorie Deficit Calculator
Estimate an intake for a weekly loss goal and see an illustrative timeline with calorie-floor warnings.
Calorie Deficit Calculator: Estimate an intake for a weekly loss goal and see an illustrative timeline with calorie-floor warnings. Runs 100% locally in your browser with zero server file uploads.
- Category
- Health & sport tools
- Runs
- In your browser
- Cost
- Free · no sign-up
- Availability
- Ready to use
Runs entirely in your browser
1961 kcal/dayEstimated maintenance
At this intake: approximately 0.50 kg/week using a constant calorie deficit.
| Weight (kg) | Weeks from now | Illustrative date |
|---|---|---|
| 68.8 | 2.5 | Calculating… |
| 67.5 | 5.0 | Calculating… |
| 66.3 | 7.5 | Calculating… |
| 65.0 | 10.0 | Calculating… |
The 3,500 kcal per pound rule is an approximation. Weight loss usually slows as energy needs change, so this timeline is not a prediction. The 1,200 kcal floor for women and 1,500 for men are general warning thresholds, not a guarantee of adequate nutrition. NIH weight-management evidence · Hall et al. · NIH Body Weight Planner
Estimates for adults only. Not suitable for pregnancy, breastfeeding or a personalised treatment plan. Activity factors are broad assumptions; actual needs vary.
Intake floors and support
NIH/NHLBI obesity evidence review includes reduced-calorie plans of 1,200–1,500 kcal/day for women and 1,500–1,800 for men. The lower bounds are warning thresholds here, not universal adequate intakes. https://www.nhlbi.nih.gov/sites/default/files/media/docs/obesity-evidence-review.pdf
NHS guidance recommends a general aim of 0.5–1 kg per week and professional support for very-low-calorie diets. https://www.nhs.uk/conditions/overweight-and-obesity/
Why the timeline is approximate
Daily deficit = requested kg/week ÷ 0.45359237 × 3,500 ÷ 7. The timeline divides the weight difference by the loss rate after applying the intake floor.
Hall et al., Quantification of the effect of energy imbalance on bodyweight (2011), explains why dynamic adaptation matters: https://pubmed.ncbi.nlm.nih.gov/21872751/ . NIH Body Weight Planner: https://www.niddk.nih.gov/bwp .
How to use it
- Enter adult body measurements and typical activity.
- Set a goal weight below your current weight and a weekly loss rate.
- Review the intake floor, adjusted rate and illustrative milestone dates.
Privacy & limitations
Your inputs stay in this browser. Nothing you enter is uploaded or saved.
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Frequently asked questions
What happens below the calorie floor?
The displayed intake is capped at 1,200 kcal/day for women or 1,500 for men. A warning shows the uncapped calculation, and the timeline uses the slower capped rate. If maintenance is no higher than the floor, no weight-loss timeline is offered.
Will I reach my goal on the displayed date?
Not necessarily. The constant 3,500 kcal per pound rule ignores changing metabolism and energy requirements; loss usually slows. The dates are arithmetic illustrations, not predictions.
Is the floor a safe intake for everyone?
No. Needs can be higher, and pregnancy, breastfeeding, age under 18 or medical conditions need individual guidance. The tool also flags a goal below adult BMI 18.5.
Free tool · runs in your browser · no account required