Weight loss date calculator

This calculator estimates when you could reach a goal weight if you lose a steady share of your body weight each week: 0.5% (gentle), 0.75% (steady) or 1% (faster), never more than 1 kg in a week. Someone at 82 kg aiming for 72 kg at the steady pace gets there in about 18 weeks, losing about 0.6 kg in the first week and a little less every week after. It is an estimate to plan with, not a deadline.

What pace is safe?

Health bodies land in a similar range:

• The NHS says to aim to lose 0.5 to 1 kg (1 to 2 lb) a week.
• The US CDC says people who lose about 1 to 2 pounds a week are more likely to keep the weight off than people who lose it faster.
• ICMR-NIN's Dietary Guidelines for Indians 2024 say weight reduction should be gradual, that losing half a kilogram a week is considered safe, and that rapid weight loss should be avoided.

Half a kilo means something different at 55 kg and at 110 kg, so the paces here are a percentage of your weight, taken from sports nutrition research. A 2014 review of contest preparation by Helms and colleagues recommends losing about 0.5 to 1% of body weight a week to hold on to muscle. A 2011 trial in elite athletes by Garthe and colleagues compared 0.7% a week with 1.4% a week and found the slower group gained lean mass and strength while the faster group did not. For most people these percentages fall inside the NHS range, and no single week goes over 1 kg.

How the projection works

Each week the tool takes your chosen percentage of that week's weight, subtracts it and repeats until you hit the goal:

• Weight next week = this week's weight − (pace % × this week's weight), capped at a 1 kg drop
• Weeks needed = the number of weeks until weight reaches the goal, with the last part-week counted as a fraction

Worked example at the steady pace, 82 kg to 72 kg:

That's about 17.3 weeks, so the goal lands early in week 18. The curve bends because the same percentage of a smaller number is fewer kilos. The orange dashed line on the chart shows week 1's loss carried on forever, which is how many people picture it.

Why weight loss slows down in real life

The percentage model is a simple way to show the slowing; the real reason is your body. Lighter bodies burn fewer calories, so eating the same amount gives a smaller deficit each week. Kevin Hall's team at the US National Institutes of Health modelled this in The Lancet in 2011 and found the body weight response to a lasting change in eating is slow, with about half of the eventual change coming in roughly a year.

So recheck your maintenance calories every 4 to 5 kg using the calorie calculator, and expect stalls: water retention, a salty meal or a period can hide a week or two of fat loss. The weight loss plateau guide covers what to check when the scale stops moving.

The calorie deficit, and why 7,700 kcal per kg is rough

The tool shows a rough daily deficit using the old rule that 1 kg of body weight is about 7,700 kcal (the metric version of 3,500 kcal per pound): deficit per day = kg lost per week × 7,700 ÷ 7. At 0.62 kg a week that's about 680 kcal a day. For comparison, ICMR-NIN describes 500 to 750 kcal a day as a typical weight-loss deficit and advises not going beyond 40% of your daily energy needs, to protect muscle.

Treat that number as a rule of thumb only. In a 2008 paper, Hall showed the energy in a kilo lost depends on how much body fat you start with: the rule roughly fits people with more than 30 kg of body fat, and leaner people lose more weight per calorie of deficit (more of it is lean tissue and water). The bigger problem, as Hall and Chow explained in 2013, is that the rule ignores the slowing above, so over months it badly overestimates how much you'll lose on a fixed diet.

If you enter your maintenance calories, the tool also shows a rough eating target for the first weeks and warns if it falls below 1,200 kcal a day for women or 1,500 for men. Going lower should only happen under medical supervision. For a ready-made menu at that level, see the 1,500-calorie Indian diet plan, and for how maintenance and deficit fit together, the calorie deficit guide and BMR vs TDEE.

Is your goal a healthy weight?

The tool uses your height to work out the BMI at your goal weight. For Asian Indians, the Indian consensus guidelines treat 18.5 to 22.9 as normal, 23 to 24.9 as overweight and 25 or more as obese. If your goal is below a BMI of 18.5, the tool flags it as underweight and shows the lowest healthy weight for your height. The ideal weight calculator gives your full healthy range.

Limits

• It doesn't know your age, sex, body fat, medicines or health conditions, and real loss is never a smooth curve.
• The first week or two often drop faster than the projection, mostly water and gut content, not fat.
• It is not for under 18s, pregnancy or breastfeeding. If you have diabetes, heart or kidney disease, a thyroid condition or a history of eating disorders, plan weight loss with your doctor.

The calories burned calculator shows what your workouts add.

Useful links

• NHS, Obesity treatment
• CDC, Losing weight
• ICMR-NIN, Dietary Guidelines for Indians 2024 (PDF)
• Helms et al. 2014, Evidence-based recommendations for natural bodybuilding contest preparation (JISSN)
• Garthe et al. 2011, Effect of two different weight-loss rates on body composition and strength (IJSNEM)
• Hall 2008, What is the required energy deficit per unit weight loss? (IJO)
• Hall et al. 2011, Quantification of the effect of energy imbalance on bodyweight (Lancet)
• Hall and Chow 2013, Why is the 3500 kcal per pound weight loss rule wrong? (IJO)
• NIDDK Body Weight Planner
• Misra et al. 2009, Consensus guidelines on obesity for Asian Indians (JAPI)

This calculator is for general information and isn't medical advice.