What is a safe rate of weight loss?

CDC and most clinical guidelines: 1-2 lb (0.5-1 kg) per week. Or: under 1% of body weight per week. Faster loss is achievable short-term but risks muscle loss, metabolic adaptation, gallstones, and rebound regain. The colored badge in the breakdown tells you which range you are in.

How much of a deficit can I sustain?

Most people can sustain 500-750 cal/day with normal food intake. Above 1,000 cal/day usually requires either very low total calories (under 1,200 for women, 1,500 for men) or heavy exercise — and adherence drops sharply over months. The conservative path is a smaller deficit you can maintain for longer.

Does this account for exercise?

Indirectly — the deficit you enter is your NET deficit AFTER any exercise calorie burn. Example: maintenance 2,200, food 1,800, exercise burns 200 -> net deficit 600. Exercise calorie estimates from fitness trackers are notoriously inflated, often by 30-50% — be conservative.

What about water weight and the first-week drop?

New deficits typically show a 2-5 lb (1-2 kg) loss in week 1 from glycogen + water depletion, not fat. The calculator assumes pure fat loss after that initial drop. Expect the rate to settle to the calculated value from week 2 onward.

Can I use this for weight gain too?

No — this calculator only handles deficits (current > goal). For muscle gain, the math is different (calorie surplus paired with progressive overload training); the relationship between surplus and lean mass gain is much less linear than fat loss.

Weight Loss Calculator

How long to lose weight at a given daily calorie deficit. Enter current weight, goal weight, and daily deficit — get the target date, weekly loss rate, and a safety check against the CDC 1-2 lb/week guideline.

Result

Estimated time to reach 160 lb

20 weeks

140 days · about 4.6 months

Total to lose20.0 lb
Weekly loss rate0.45 kg/wk equivalent1.00 lb/wk
% body weight per weekMedical consensus: 0.5–1% per week is sustainable; above 1% risks muscle loss and metabolic adaptation.0.56%Healthy
Days to goal140 days
25% milestone weightReached around week 5175.0 lb
50% milestone weightReached around week 10170.0 lb
75% milestone weightReached around week 15165.0 lb

1.00 lb/wk — sustainable per CDC

Source: CDC: Healthy weight loss is 1–2 pounds per week. Mayo Clinic + USDA Dietary Guidelines: 500–750 cal/day deficit is the standard recommendation.

Not medical advice — Estimate only — not medical advice. The 3,500-cal-per-pound rule overstates actual loss because TDEE drops as you lose weight (metabolic adaptation); real loss slows by 5-15% over 3 months. Consult a physician before any aggressive deficit, especially with diabetes, heart disease, eating-disorder history, or during pregnancy/breastfeeding.

How to use this calculator

Pick units (lb or kg).
Enter current weight and goal weight.
Enter your daily calorie deficit — typically 500 cal/day for steady 1 lb/wk loss; 750 for ~1.5 lb/wk; 1,000 is aggressive.
Read the timeline. If the % body weight per week badge turns yellow or red, reduce the deficit to stay sustainable.

About this tool

Weight loss is energy in minus energy out. A 500-cal/day deficit produces about 1 lb (0.45 kg) per week, by the long-standing rule that a pound of body fat stores roughly 3,500 calories. This calculator works backward from your goal: enter where you are, where you want to be, and how big a daily deficit you can sustain — it returns the target date, weekly loss rate, and a safety check against medical-consensus limits (CDC: 1-2 lb/wk; clinical guidance: under 1% of body weight per week to avoid muscle loss and metabolic slowdown).

Frequently asked

It is a useful approximation for short timeframes but overstates long-term loss. As you lose weight, your TDEE drops (smaller body burns fewer calories), so the same deficit produces less loss over time. Expect actual loss to be 5-15% slower than the linear estimate over 3+ months. Re-run the calculator with updated weight every few weeks.

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