Weight Loss Percentage Calculator
The percentage you have lost, your 5% and 10% milestones, and how far a goal weight is.
The calculator never sends or saves what you type.
A price or another fall, not a weight? Percentage decrease calculator. Know what you lost and the percentage? Find your starting weight with X is Y% of what number. Want your body fat instead? Body fat percentage calculator.
On this page
- How to calculate weight loss percentage
- Worked examples
- 5% and 10% weight loss chart (lb and kg)
- Where the 5% and 10% milestones come from
- Weight loss percentage in kg, lb or stone
- When the weight is up, not down
- Baby and newborn weight loss percentage (grams)
- Tracking weight loss percentage week by week (Excel or Sheets)
- Frequently asked questions
How to calculate weight loss percentage
Weight loss % = (Start − Current) ÷ Start × 100
The percentage of weight loss is the weight you have lost divided by the starting weight, always: it says what share of the weight you began with has gone. Both weights in one unit; the unit cancels, so pounds and kilograms give the same figure. The calculator rounds to two decimals, trims zeros (10%, not 10.00%), and never rounds a figure onto 5% or 10% unless the loss is exactly that.
Worked examples
220 lb to 198 lb.
- Weight lost = 220 − 198 = 22 lb
- 22 ÷ 220 = 0.1
- 0.1 × 100 = 10% lost
- Check: 220 − 10% = 198
In kilograms, 95 kg to 88 kg is 7 ÷ 95 × 100 ≈ 7.37%. The check line reads ≈ rather than =, because 7.37% is rounded: 95 − 7.37% is 87.9985, not 88. With a goal of 198 lb from 220 lb and 205 lb today, the calculator adds the goal line: 7 lb to go, a goal 10% below your start.
Each link reloads the calculator with those weights.
5% and 10% weight loss chart (lb and kg)
Goal weight = starting weight × 0.95 for 5%, or × 0.90 for 10%. So 5% of 220 lb is 11 lb, and the goal is 209 lb. The figure in brackets is the weight lost. While the goal box is empty, the calculator prints both under the answer for any loss.
In pounds
| Starting weight | After 5% | After 10% |
|---|---|---|
| 150 lb | 142.5 (−7.5) | 135 (−15) |
| 180 lb | 171 (−9) | 162 (−18) |
| 200 lb | 190 (−10) | 180 (−20) |
| 220 lb | 209 (−11) | 198 (−22) |
| 240 lb | 228 (−12) | 216 (−24) |
| 300 lb | 285 (−15) | 270 (−30) |
In kilograms
| Starting weight | After 5% | After 10% |
|---|---|---|
| 72 kg | 68.4 (−3.6) | 64.8 (−7.2) |
| 80 kg | 76 (−4) | 72 (−8) |
| 90 kg | 85.5 (−4.5) | 81 (−9) |
| 100 kg | 95 (−5) | 90 (−10) |
| 120 kg | 114 (−6) | 108 (−12) |
Starting weight not in the table? Multiply your own the same way. From 238 lb: 238 × 0.95 = 226.1 lb and 238 × 0.90 = 214.2 lb, so 10% is 23.8 lb. At 214 lb the calculator shows 10.08%, just past it: 238 → 214.2 lb. Only know today’s weight after a 10% loss? Divide by 0.90 to get the start (198 ÷ 0.90 = 220) — or use the reverse percentage calculator.
Where the 5% and 10% milestones come from
Public health guidance names 5% and 10% of your starting weight as first targets; the exact words are quoted in the FAQ below. Sources checked 6 October 2026:
- NIDDK, “Health Tips for Adults” — last reviewed September 2020.
- CDC, “Steps for Losing Weight” — last reviewed 17 January 2025.
- NHS, “Overweight and obesity in adults” — last reviewed 29 April 2026.
Weight loss percentage in kg, lb or stone
Type the unit after the number if you like — 95 kg, 198 lb, 10 st — as long as every weight uses the same one. If they differ, the calculator shows the conversion rather than an answer: 95 kg is 95,000 g; 10 st is 140 lb. Kilograms and pounds do not convert by a whole number (1 lb is exactly 0.45359237 kg; 1 kg ≈ 2.2046 lb), so the calculator does not guess: convert one yourself and use the result. Pounds and ounces: 7 lb 5 oz is 7 + 5 ÷ 16 = 7.3125 lb.
In stone and pounds, multiply the stones by 14 and add the pounds: 15 st 10 lb is 15 × 14 + 10 = 220 lb, and 14 st 2 lb is 14 × 14 + 2 = 198 lb, so 15 st 10 lb to 14 st 2 lb is 10% lost. The boxes take decimal stone (15.5 st in both); type “10 st 4” and the calculator tells you it is 144 lb, so you can enter both weights in pounds.
When the weight is up, not down
If the current weight is higher than the start, the calculator says so: 180 lb to 184.5 lb shows 2.5% under “Weight gained”, not a negative loss, and notes that as a percentage change it is +2.5% — the figure the percentage change calculator prints. A loss of half the starting weight or more is almost always two units mixed (200 lb typed against 90 kg) or the boxes swapped; the calculator shows the figure and says to check.
Baby and newborn weight loss percentage (grams)
Babies are weighed in grams, and the arithmetic is the same: birth weight minus today’s weight, divided by the birth weight. 3400 g to 3150 g is 250 ÷ 3400 × 100 ≈ 7.35%. This page does the arithmetic only — ask your midwife or paediatrician what the figure means for your baby.
Tracking weight loss percentage week by week (Excel or Sheets)
With the starting weight in A1 and today’s weight in B1, enter =(A1-B1)/A1 and format the cell as a percentage, or =(A1-B1)/A1*100 for a plain number.
For a column of weekly weigh-ins, always divide by the FIRST weight: put it in A2, the weigh-ins in B3 down, and lock the start cell with =($A$2-B3)/$A$2, then fill down. Weekly percentages do not add up: from 100 lb, losing 5% one week (to 95 lb) and 5% of the new weight the next (to 90.25 lb) is 9.75% in total, not 10% — the calculator gives 9.75% for 100 to 90.25.
Frequently asked questions
How do I calculate my weight loss percentage?
Subtract your current weight from your starting weight, divide by the starting weight, and multiply by 100. From 220 lb to 198 lb: 220 − 198 = 22, and 22 ÷ 220 × 100 = 10%. Use the same unit for both weights. The calculator does the division exactly and shows the check: 220 − 10% = 198.
What is 5% or 10% of my body weight?
Multiply your weight by 0.05 or by 0.10. For 220 lb, 5% is 11 lb and 10% is 22 lb, so the weights after losing them are 209 lb and 198 lb (220 × 0.95 and 220 × 0.90). For 90 kg, 5% is 4.5 kg and 10% is 9 kg: 85.5 kg and 81 kg. With no goal weight entered, the calculator prints both milestones under any loss.
Does it matter whether I use pounds, kilograms or stone?
No — converting both weights to another unit multiplies them by the same number, so the percentage is the same. Use one unit for both. For stone, convert to pounds first: 11 st 7 lb is 11 × 14 + 7 = 161 lb, and 161 lb to 150 lb is about 6.83%. You can type the unit after each number (95 kg, 198 lb, 10 st); if the two differ, the calculator tells you how to convert instead of giving an answer.
What does losing 5% or 10% of my weight mean?
It means the weight you have lost is 5% or 10% of the weight you started at — 11 lb or 22 lb from 220 lb. The NIDDK (US National Institutes of Health; page last reviewed September 2020): “Experts recommend beginning with a weight loss of 5 to 10 percent of your starting weight over a period of 6 months.” The CDC (last reviewed 17 January 2025): “For example, a 5% weight reduction for a person who weighs 200 pounds is 10 pounds. This change could lower the risk for some chronic diseases such as heart disease, prediabetes, and type 2 diabetes.” The NHS (last reviewed 29 April 2026): “Just losing a small amount of weight (5 to 10% of your body weight) can improve your health.” With no goal weight entered, the calculator shows both milestones under a loss. It does the arithmetic only; what weight or pace is right for you is a question for your clinician.
How do I find my goal weight for a 10% loss, or my starting weight from a loss?
Goal weight = starting weight × 0.90 for 10%, or × 0.95 for 5%: from 238 lb that is 214.2 lb. Enter it as the goal and the calculator shows how far you are from it. The other way round — you lost 22 lb and it was 10%, so what did you start at? — is 22 ÷ 0.10 = 220 lb, which the X is Y% of what number calculator answers. If you know only today’s weight after a 10% loss, divide by 0.90: 198 ÷ 0.90 = 220 lb, which the reverse percentage calculator does.
How do I work out a newborn’s weight loss percentage?
The same way, in grams: birth weight minus current weight, divided by the birth weight, times 100. A baby born at 3400 g who weighs 3150 g has lost 250 g, which is about 7.35%. This page only does the arithmetic — see a clinician, such as your midwife or paediatrician, about what the figure means for your baby.
Why does the calculator say “gained”?
Because the current weight is higher than the starting weight. From 180 lb to 184.5 lb the change is 4.5 lb up, 2.5% of the start, so the calculator shows 2.5% with “Weight gained” rather than a negative loss. As a signed percentage change that is +2.5%, which is how the percentage decrease calculator would report it (as a rise).
Is the percentage of my goal completed the same as the percentage lost?
No. From 220 lb toward a goal of 198 lb, at 209 lb you are halfway to the goal, but you have lost 5% of your starting weight. The calculator prints the second figure — the share of your starting weight that has gone — and how far is left: 11 lb to go, a goal 10% below your start.
Is weight loss percentage the same as body fat percentage?
No. Weight loss percentage is the share of your STARTING weight that has gone; body fat percentage is the share of your CURRENT weight that is fat. Losing 10% of your weight does not lower your body fat percentage by 10 points — the two are measured against different things.
How do weight loss challenges calculate the percentage?
Each person’s loss is divided by their OWN starting weight, so people of different sizes can be compared fairly. 20 lb lost from 250 lb is 8%, while 15 lb lost from 160 lb is about 9.38% — the smaller loss ranks higher. Weigh everyone on the same scale at the same time of day.