UK weight-loss calculator
Weight loss percentage calculator
Enter your starting weight and your weight now to see what percentage of your body weight you have lost, and where the 5% and 10% marks sit.
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I started at st lb and I’m now st lb.
2blanks still to fill
Enter your starting weight and your weight now to see the percentage change.
Why percentage is the more useful number
Half a stone means something quite different at 20 stone than at 10 stone. Percentage puts your progress in proportion to where you started, which is both fairer to you and closer to how the health benefits actually work.
It is also why 5% and 10% are the figures used clinically. Those thresholds are associated with meaningful improvements in things like blood pressure, blood glucose and cholesterol, and they arrive far sooner than most people’s final goal.
| Starting weight | 5% is | 10% is |
|---|---|---|
| 10 st (63.5 kg) | 7 lb (3.2 kg) | 1 st (6.4 kg) |
| 14 st (88.9 kg) | 9.8 lb (4.4 kg) | 1 st 5.6 lb (8.9 kg) |
| 18 st (114.3 kg) | 12.6 lb (5.7 kg) | 1 st 11.2 lb (11.4 kg) |
| 22 st (139.7 kg) | 1 st 1.4 lb (7 kg) | 2 st 2.8 lb (14 kg) |
How is this calculated?
percentage = (starting weight − current weight) ÷ starting weight × 100Note that the divisor is your starting weight, not your current weight. Dividing by the current figure would give a slightly larger and less meaningful number: losing 10 kg from 100 kg is a 10% loss, not 11.1%.
You can enter your weights in stone and pounds, kilograms or pounds. They are converted to a common base before the calculation, so mixing up which unit you were thinking in cannot skew the result.
Reading the number sensibly
Weight fluctuates day to day
Food still in your system, fluid, salt intake, hormones and exercise can move the scales by a kilogram or more within a single day. Comparing measurements taken at a similar time, in similar conditions, tells you far more than any one reading.
- The scales cannot distinguish fat from muscle, fluid or the contents of your gut.
- A flat week is common and does not mean nothing is happening.
- A weekly average is more informative than a daily figure, if you weigh often.
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Frequently asked questions
How do I calculate my weight loss percentage?
Subtract your current weight from your starting weight, divide the result by your starting weight, and multiply by 100. For example, going from 100 kg to 92 kg is 8 ÷ 100 × 100 = 8%.
Why is 5% considered significant?
A reduction of around 5% of body weight is widely used as a threshold for clinically meaningful benefit; it is associated with improvements in blood pressure, blood glucose control and cholesterol. It is also a realistic first goal, which matters, because a goal you reach is worth more than one you abandon.
Is my percentage good progress?
There is no single right answer, but a rate of roughly 0.5 to 1% of body weight a week is a common guide, in line with the NHS suggestion of 0.5 to 1 kg a week for most people. Slower than that is still progress.
Sources
Important information
The calculators on this site provide general information and estimates. They are not medical advice and they do not diagnose any condition.
Everyone is different, and individual energy needs vary for reasons these equations cannot capture. If you have a health condition, take medication, are pregnant or breastfeeding, or have any concerns about your weight, speak to your GP, pharmacist or a registered dietitian.