Calculate what percentage of your body weight you have lost
This calculator provides estimates only. Consult your GP or a healthcare professional for personalised advice.
Knowing what percentage of your body weight you have lost is one of the most useful ways to measure progress on a weight loss journey. The NHS and other health organisations use percentage-based targets because they are more meaningful than absolute numbers. Losing 5 kg means something very different for someone who weighs 60 kg versus someone who weighs 120 kg; the percentage puts the loss in proper context. Research consistently shows that losing 5-10% of your body weight is associated with significant health benefits, including reduced risk of type 2 diabetes, lower blood pressure, improved cholesterol levels, and reduced strain on joints. The NHS specifically highlights that even modest weight loss in this range can make a real difference to long-term health outcomes, particularly for people who are overweight or living with obesity. This calculator takes your starting weight and current weight, computes the percentage lost, converts the loss into both kilograms and stones/pounds (for UK users), and tells you whether your loss falls into a clinically significant range. It is a simple but powerful way to track and celebrate your progress.
To use this calculator: 1. Enter your starting weight in kilograms. This is the weight you were at before you began your weight loss effort. If you weigh yourself in stones, multiply by 6.35 to convert: for example, 14 stone = 88.9 kg. 2. Enter your current weight in kilograms. This is your most recent weigh-in. 3. The calculator will display: - Your weight loss as a percentage of your starting weight - The total amount lost in kilograms - The total amount lost in stones and pounds - A clinical significance rating based on NHS thresholds 4. Use the pie chart to visualise the proportion of weight lost compared to your current weight. 5. If your percentage is between 5% and 10%, you have achieved clinically significant weight loss. If it exceeds 10%, the calculator recommends consulting your GP for monitoring.
The weight loss percentage formula is straightforward: Percentage Lost = ((Starting Weight - Current Weight) / Starting Weight) x 100 For example, if your starting weight was 90 kg and your current weight is 82 kg: Percentage Lost = ((90 - 82) / 90) x 100 = (8 / 90) x 100 = 8.9% The calculator also converts the loss to stones and pounds using these conversion factors: - 1 kg = 2.20462 lbs - 14 lbs = 1 stone So 8 kg lost = 17.6 lbs = 1 stone 4 lbs (approximately). The NHS significance thresholds are: - 0% or less: no weight loss recorded - Above 0% but below 5%: good progress, keep going - 5% to 10%: clinically significant, associated with reduced health risks - 10% or more: major weight loss, consult your GP for monitoring
Inputs: Starting Weight: 90 kg, Current Weight: 82 kg
Inputs: Starting Weight: 100 kg, Current Weight: 90 kg
Inputs: Starting Weight: 75 kg, Current Weight: 72 kg
This calculator is designed for adults aged 18 and over. For children and teenagers, weight management should always be supervised by a healthcare professional. If you are losing weight unintentionally (without trying), you should see your GP as unexplained weight loss can be a symptom of underlying health conditions. The NHS recommends aiming for gradual weight loss of 0.5 to 1 kg per week for sustainable, long-term results.