Weight Loss Percentage Calculator and Plateau Check
Enter your starting weight, current weight, and how many weeks have passed. You get your weight loss percentage, how much of your goal you have already banked, and whether your weekly change is actually bigger than your own scale noise. With a typical 0.5 kg day-to-day swing, a weekly loss slower than about 0.53 kg is invisible week to week.
That is 6.4 kg (14.0 lb) down from your starting weight.
47% of the way to your goal weight · 7.3 kg left.
Average rate: 0.53 kg per week (0.58% of starting weight per week).
Your noise floor is 0.53 kg per week. Your observed rate is below it, so a single week proves nothing. Judge in blocks of 2 weeks.
At this rate, about 14 more weeks to goal.
Why percentage beats kilograms
Two people can both lose 5 kg and have done completely different amounts of work. For someone starting at 60 kg that is 8.3 percent of their body. For someone starting at 120 kg it is 4.2 percent. Percentage is the only version of the number that is comparable between people, and it is also the version that makes plateaus make sense: as you get lighter, the same weekly deficit is a smaller absolute loss but roughly the same percentage of a smaller body.
The second number worth tracking is the percentage of your goal achieved, which is lost weight divided by total weight you intended to lose. That one keeps motivation honest in the middle of a long cut, when the mirror has not caught up yet.
Computed: what each weekly rate adds up to
The table below was computed by compounding a fixed weekly rate of body weight. Week n weight is starting weight times (1 minus rate) to the power n. The percentage column is independent of your starting size; the kilogram columns use a 90 kg and a 70 kg start as examples.
In kilograms, a 90 kg person losing 0.50 percent per week reaches 88.2 kg at four weeks, 86.5 kg at eight, 84.7 kg at twelve, and 79.8 kg at twenty-four. At 1.00 percent per week the same person reaches 86.5 kg at four weeks and 70.7 kg at twenty-four.
Computed: what the common milestones weigh
Five, ten, fifteen and twenty percent of starting weight are the checkpoint levels many programmes use. The table is pure arithmetic on each starting weight: the first number is the kilograms to lose, the second is the weight you would land on.
Computed: when a plateau is real and when it is just noise
A bathroom scale does not measure fat, it measures whatever is on the scale that morning, and water swings it. If your daily weigh-ins have a standard deviation of sigma kilograms, then a mean of seven of them has a standard error of sigma divided by the square root of seven. Comparing two consecutive weekly means doubles the variance, so a change has to clear about 1.07 x sigma before you can call it real at 95 percent confidence. Every number below follows from that single line of arithmetic.
Now divide that detection threshold by your actual rate of loss, and you get how many weeks of data you need before a flat reading means something. This is the plateau table.
The practical reading: if you are losing slowly and your scale is noisy, a single stalled week is meaningless. Someone dropping 0.25 kg per week with a 1.0 kg daily swing needs more than four weeks of flat data before the word plateau is justified. Someone dropping 0.75 kg per week with a steady 0.3 kg swing can call it in under a week.
How to make the percentage trustworthy
- Weigh daily, decide weekly. Daily data is what lets averaging reduce the noise; weekly averages are what you actually read.
- Fix one condition. Same time, after the bathroom, before food and drink. Most of the swing you are fighting is water and gut contents.
- Pick a start weight you can defend. Take the average of your first week, not your heaviest ever morning.
- Recalculate the percentage every two to four weeks. More often than that and you are reading noise.
- Watch the percentage, not the kilograms, once you are deep in a cut. Absolute loss slows as you get lighter even when nothing has gone wrong.
- Expect the first week to be wrong. Early rapid drops are largely glycogen and water, not tissue.
Not medical advice. This is tracking arithmetic, not clinical guidance. If you have health concerns or a medical reason to manage your weight, talk to a qualified healthcare professional. See our disclaimer.
Frequently asked questions
How do I calculate my weight loss percentage?
Subtract your current weight from your starting weight, divide by your starting weight, and multiply by 100. Losing 6.3 kg from 90 kg is 7.0 percent. The calculator above does it in both kilograms and pounds.
What is a good weight loss percentage?
It depends entirely on your timeline and starting point. The trajectory table above shows what each sustained weekly rate compounds to: 0.5 percent per week reaches about 11.3 percent in twenty-four weeks, and 1.0 percent per week reaches about 21.4 percent in the same period.
Why has my weight not moved for a week?
Check it against your noise floor first. With a typical 0.5 kg daily swing you need a weekly change larger than about 0.53 kg before it is distinguishable from water movement. One flat week is not a plateau.
How many weeks before I can call it a plateau?
Divide 1.07 times your daily swing by your weekly rate of loss. At 0.5 kg per week with a 0.5 kg daily swing that is about 1.1 weeks; at 0.25 kg per week with a 1.0 kg swing it is over four weeks.
Should I track kilograms or percentage?
Percentage, if you want to compare yourself with anyone else or with your own past at a different size. Kilograms are fine for day-to-day decisions, but they shrink in meaning as you get lighter.
Does this tell me how much fat I have lost?
No. A scale cannot separate fat from water, glycogen, or muscle. For composition, pair this with a body fat estimate and track both over the same window.
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