Weight loss calculator: when could you reach your goal?

Enter your current weight, the weight you are aiming for and a weekly pace, and this weight loss calculator shows a likely goal date plus your first milestone on the way.

How to use the goal date calculator

You need three things: today’s weight, a goal weight below it, and the pace you want to plan with. Choose metric (kg) or imperial (lb) first, then press Calculate.

Weigh yourself in the morning, after using the toilet and before breakfast, in similar clothing each time. That gives the most comparable starting number. A single weigh-in is fine to begin with; later on, a weekly average tells you more.

The pace menu offers four options: 0.25, 0.5, 0.75 or 1 kg per week (roughly 0.5, 1, 1.5 or 2 lb). The calculator starts on 0.5 kg because it suits most adults. Try a slower pace too, and compare the dates; for many people the extra weeks buy a calmer, more enjoyable plan.

How to read your result

The result box shows four lines. Each one answers a slightly different question, so it helps to read them together rather than focusing on the date alone.

If the date feels far away, that is common and not a reason to give up. A long timeline simply means a goal that deserves stepping stones. Write the 5% milestone on the calendar as well, and plan a small reward for it that has nothing to do with food.

If the date feels very close, check that the pace is one you could keep up during a busy month, a holiday or an illness. Plans that only work when life is quiet rarely survive the first difficult week.

Why the calculator adds a 5% milestone

Losing a twentieth of your weight is a turning point that many people overlook. Studies in people with type 2 diabetes have linked it to better blood sugar, blood pressure and blood fats. The weight loss percentage calculator, linked at the end of this page, explains what 5, 10 and 15% can mean for your health in detail.

What is a realistic pace of weight loss?

For most adults, somewhere between 0.25 and 1 kg a week is a realistic pace, with about 0.5 kg as a sensible middle. People who start at a higher weight often lose faster in the first weeks, and almost everyone slows down later.

A large review of 80 weight loss trials, covering more than 26,000 adults, found a clear pattern. Programmes based on eating less produced an average loss of roughly 5 to 9% of body weight by six months. After that, weight loss began to level off in nearly every type of programme, and some weight came back over the following years.

That review also showed what advice alone or exercise alone achieved: very little on the scale. Changes in food did most of the weight work, while activity added to it and helped people hold on to what they had lost.

Is slow weight loss better than fast?

Speed on its own matters less than many people think. In an Australian trial, 200 adults lost weight either quickly over 12 weeks or gradually over 36 weeks. Three years later, both groups had regained about 70% of what they lost.

The quick group in that study followed a very-low-calorie programme with meal replacements and close professional follow-up. That is very different from cutting meals on your own. Unsupervised crash diets can leave you tired, irritable and short of nutrients, and they are not something Obesity Foundation recommends.

The useful lesson is this: what you do after the weight comes off decides more than how fast it came off. Pick a pace you can enjoy, and start building habits that you would happily keep for years. Our page on weight regain looks at the long term in depth.

Why your weight does not drop in a straight line

Your weight on any given morning is the sum of fat, muscle, bone, water, food in your gut and stored carbohydrate. Only one of these, fat, is what you are trying to change, and it changes slowly. The others swing from day to day.

Some common reasons the scale jumps or stalls:

• Water and salt. A salty takeaway can make you hold extra fluid for a day or two.
• Stored carbohydrate. The body keeps glycogen in muscles and liver together with water. Eating fewer starchy foods empties some of that store, which explains part of the quick drop many people see in week one.
• The menstrual cycle. Many women notice a temporary rise in the days before a period.
• Bowel contents and timing. A late meal, constipation or weighing at a different time of day all shift the number.
• New exercise. Starting strength work can cause some short-term fluid retention in the muscles while they recover.

A European study of more than 1,400 adults who weighed themselves on smart scales showed how regular these swings are. Weight tended to rise over the weekend and fall again during the week, by about 0.35% on average. Over the Christmas period, people gained around 1.35%, and not all of it disappeared in the following months.

To keep that festive rise small without giving up the celebrations, see our guide to holiday weight gain.

So a week with a higher number is not a failure. It may be water, a weekend or simply noise. Look at the direction over four weeks before you decide whether something needs to change.

A calmer way to track progress

Two options work well. You can weigh once a week on the same day under the same conditions. Or you can weigh most mornings and look only at the weekly average. Both smooth out the daily wobble.

If weighing makes you anxious, low or obsessive, step back from it. A tape measure around the waist, how your clothes fit, your blood pressure, your energy or how far you can walk all show progress too.

Why weight loss slows and plateaus happen

As you lose weight, your body needs less energy, so the same eating plan produces a smaller and smaller deficit. A lighter body uses less fuel to move and to keep itself running, much like a smaller car uses less petrol.

On top of that, the body defends its weight. Energy use can fall a little further than size alone explains, and hunger signals usually grow stronger. A follow-up of contestants from a televised weight loss show found that their resting energy use was still lower than expected six years later.

Researchers at the US National Institutes of Health used a mathematical model to show how much the old rule of thumb, 3,500 kcal for every pound, overestimates weight loss over time. According to their work, a lasting change in what you eat moves your weight slowly: about half the eventual change happens in the first year, and close to all of it after about three years.

In practical terms, a long plateau after several months is the expected shape of the curve. It is not proof that you are doing something wrong.

What to do when the scale stops moving

1. Wait four weeks. Short stalls often break on their own once water balance settles.
2. Check the quiet drift. Portions, snacks and drinks tend to creep back over time. A few days of noting what you eat can show where.
3. Add strength. Muscle work twice a week helps protect muscle while you lose fat. The Start videos in our free workouts are designed for this.
4. Look at sleep and stress. Short nights and constant stress make hunger harder to manage; see sleep, stress and mental health.
5. Consider a maintenance phase. Holding a new, lower weight steady for a while is a real achievement. It also gives you practice for the long run.

The formula behind the calculator

The tool uses simple arithmetic, so you can check every result by hand. It first subtracts your goal weight from your current weight. It then divides that difference by your weekly pace to get the number of weeks.

Finally it adds those weeks to today’s date. The number of weeks is rounded up, so the result never promises a shorter timeline than the maths supports.

An example: someone weighing 118 kg sets a goal of 104 kg and chooses 0.5 kg per week. The difference is 14 kg; divided by 0.5 that gives 28 weeks, or about six and a half months. Their 5% milestone is 118 × 0.95 = about 112 kg, which at the same pace lies around 12 weeks away.

If you switch to pounds, the calculator converts your entries behind the scenes, so the weeks and the date stay the same.

Why we keep it simple on purpose

More complex models exist. They take into account that energy needs fall as weight falls, and they predict a curve that slowly flattens. Those models are closer to reality, but they ask for more details and still cannot know about your holidays, illnesses or busy months.

A straight-line estimate is easy to understand and easy to adjust. Treat it as a first sketch and update it every month or two with your real progress. If you want to know how many calories a given pace might take, use the calorie deficit calculator, which never suggests eating below a safe minimum.

Do the first weeks predict the long run?

To some extent. In the Look AHEAD study of adults with type 2 diabetes, those who lost more weight in the first two months of the programme tended to have lost more after eight years.

That finding is encouraging if you have a good start. If your start is slow, it is a signal to ask for more support early, not a sign that you cannot succeed. Plenty of people find their rhythm only after a few months.

Limits of the calculator and who should be careful

This tool estimates time; it says nothing about whether a goal is right for your health. Please talk to your doctor before you plan weight loss if any of the following applies to you.

• You are pregnant or breastfeeding. Weight loss is not a goal during pregnancy. Follow the advice of your midwife or doctor.
• You use insulin or other medicines that lower blood sugar. Eating less can lead to low blood sugar, and doses may need adjusting as your weight changes.
• You take blood pressure medicines or water tablets. As weight falls, blood pressure often falls too, sometimes enough to make you dizzy.
• You have, or have had, an eating disorder. Goal dates and daily weighing can feed unhealthy patterns. Work with a professional and consider leaving numbers aside; our page on psychological support can help.
• You are over about 65. Protecting muscle and bone matters more than speed. Slower paces combined with strength work are usually wiser.
• You are under 18. Growing bodies need different advice. This calculator is designed for adults.
• You have kidney, heart or liver disease, or you have lost weight without trying. Unexplained weight loss always needs a medical check.

People living with a higher weight sometimes lose more in the first weeks and may be told that faster plans are fine for them. That can be true under supervision. Without it, a steady pace is the safer default, especially if you also have joint pain or another health condition.

How to choose a goal weight that helps you

A good goal is one you can reach and then keep. For many people, that is not the number on a chart but a loss of 5 to 10% of their current weight, followed by a period of keeping it steady.

The healthy weight calculator shows the weight range linked to a BMI of 18.5 to 24.9 for your height. It is useful background, but it does not have to be your target. Health gains do not wait until you reach that range.

Some people set goals that are not about weight at all: walking to the shops without stopping, climbing stairs with less knee pain, or lowering a blood test result. These goals are just as valid and often keep motivation going when the scale stalls.

Weight is shaped by genes, biology, sleep, stress, medicines and the food around you, as well as by daily choices. Whatever your goal, be as kind to yourself on slow weeks as you would be to a friend.

What to do next: a plan you can keep

A date on a screen only becomes real through what you eat, how you move and who supports you. These three steps fit almost every body and every budget. Talk to your doctor first if you have a health condition or take regular medicines.

1. Change your plate, not your whole life

Start with one or two swaps that you would not mind keeping forever: water instead of sweet drinks, an extra portion of vegetables at dinner, a high-protein breakfast that keeps you full until lunch. Our free eating plan builds on everyday food, without banned lists or crash diets.

2. Walk most days, starting small

Walking adds to the effect of eating changes and is one of the habits most often seen in people who keep weight off. Five or ten minutes is a perfectly good start. The walking plan shows how to build up week by week.

3. Protect your muscles with Start workouts

Muscle helps you stay strong and mobile while you lose fat. Our Start level is designed for people who have not exercised in years, with chair support and gentle movements. Find the full range on the workouts page.

Get support along the way

Plans work better with someone in your corner. Obesity Foundation is a non-profit, and everything below is free.

• Book a free personal video meeting (in English) to talk through your goal, your timeline and what might get in the way.
• Join the Obesity Foundation Club to note your weekly weight, your walks and your milestones in one private place.
• Read about lifestyle treatment if you would like professional help with food, activity and habits.

Related calculators

• Weight loss percentage calculator: turn kilos lost into a percentage and see your 5, 10 and 15% milestones.
• Calorie deficit calculator: estimate a daily calorie target for your chosen pace.
• Body fat calculator: follow changes in body fat with a tape measure, not just the scale.