Weight Loss Percentage Calculator

Enter your starting weight and current weight to instantly calculate your percentage of weight loss. Works in pounds and kilograms. Free, fast, no signup required.

e.g. your weight before you started
e.g. your weight today
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What Is Weight Loss Percentage?

A weight loss percentage expresses how much of your original body weight you have lost, relative to your starting point. Instead of tracking raw pounds or kilograms — which can be misleading because the same absolute loss means very different things for different body sizes — a percentage of weight loss puts your progress in context. Losing 20 lbs means something very different if you started at 150 lbs versus 300 lbs.

This is why doctors, researchers, and clinical studies consistently use weight loss percentage rather than absolute weight loss when assessing health outcomes. A reduction of 5–10% of starting body weight is the threshold most commonly cited for meaningful improvements in blood pressure, blood sugar, cholesterol, and joint pain — regardless of how much a person weighs to begin with.

This weight loss percentage calculator gives you an instant, accurate reading in both pounds and kilograms. Whether you are tracking personal fitness progress, competing in a weight loss challenge percentage calculator competition like the Biggest Loser format, or monitoring health metrics for a medical program, the calculation is the same — and this tool does it in one click. Use it as your go-to percentage of weight loss calculator whenever you need to check your progress, and for tracking over time, see the calculating percentage of weight loss over multiple weeks section below.

How to Calculate Weight Loss Percentage

The weight loss percentage calculation formula is straightforward. You need two numbers: your starting weight and your current weight, both in the same unit.

Weight Loss % = ((Starting Weight − Current Weight) ÷ Starting Weight) × 100

Step-by-Step Example (lbs)

Step 1: Find the weight lost. Starting weight 200 lbs, current weight 175 lbs → weight lost = 200 − 175 = 25 lbs.

Step 2: Divide by starting weight. 25 ÷ 200 = 0.125.

Step 3: Multiply by 100. 0.125 × 100 = 12.5% weight loss.

How to Calculate Weight Loss Percentage in kg

The formula is identical — just use kilograms throughout. Starting weight 90 kg, current weight 81 kg → ((90 − 81) ÷ 90) × 100 = 10%. Select the kg unit button in the calculator above and the tool handles the conversion automatically.

How to Calculate Weight Loss Percentage in Excel

To calculate weight loss percentage in Excel, place your starting weight in cell A1 and your current weight in B1. In cell C1, enter:

Weight loss %: =(A1-B1)/A1*100

As a formatted percentage: =(A1-B1)/A1 then format as %

Weight lost (absolute): =A1-B1

These formulas work identically in Google Sheets. Drag down to apply to an entire tracking column. You can also add a fourth column to track cumulative percentage loss over time by always referencing the original starting weight in column A.

How to figure percentage weight loss for a competition: Most weight loss challenge percentage calculator competitions — including Biggest Loser-style office challenges — use exactly this formula. Every participant's percentage is calculated from their own starting weight, which makes it fair regardless of body size. The person who loses the highest percentage wins, not the person who loses the most pounds.

What Your Weight Loss Percentage Means

Numbers are motivating, but context matters. Here is what different percentages of weight loss typically mean for health outcomes, based on widely cited clinical research.

3–5%
Clinically meaningful — improves blood sugar and triglycerides
5–7%
Reduces risk of Type 2 diabetes by up to 58% in at-risk individuals
5–10%
Improves blood pressure, cholesterol, sleep apnea, and joint pain
10–15%
Significant metabolic improvements — often reduces medication needs
15%+
Major health transformation — associated with remission of Type 2 diabetes

Important: This calculator measures percentage of body weight lost — not body fat percentage. Body fat percentage requires separate measurements (skinfold calipers, DEXA scan, or bioelectrical impedance). Weight loss percentage and body fat percentage change are related but not the same thing. Always consult a healthcare professional for personalised guidance on weight loss goals and health targets.

Weight Loss Percentage Examples — Click to Calculate

Click any example to see the full weight loss percentage calculation instantly.

200 lbs → 180 lbs
10%
Lost 20 lbs
250 lbs → 225 lbs
10%
Lost 25 lbs
180 lbs → 162 lbs
10%
Lost 18 lbs
220 lbs → 187 lbs
15%
Lost 33 lbs
150 lbs → 135 lbs
10%
Lost 15 lbs
100 kg → 85 kg
15%
Lost 15 kg

Weight Loss Percentage Reference Table

Use this table to quickly see what percentage different weight losses represent from various starting weights.

Starting Weight5% Loss10% Loss15% Loss20% Loss
150 lbs (68 kg)7.5 lbs15 lbs22.5 lbs30 lbs
175 lbs (79 kg)8.75 lbs17.5 lbs26.25 lbs35 lbs
200 lbs (91 kg)10 lbs20 lbs30 lbs40 lbs
225 lbs (102 kg)11.25 lbs22.5 lbs33.75 lbs45 lbs
250 lbs (113 kg)12.5 lbs25 lbs37.5 lbs50 lbs
300 lbs (136 kg)15 lbs30 lbs45 lbs60 lbs
80 kg (176 lbs)4 kg8 kg12 kg16 kg
100 kg (220 lbs)5 kg10 kg15 kg20 kg

Frequently Asked Questions

How do you calculate weight loss percentage?
Subtract your current weight from your starting weight to get the weight lost, divide by your starting weight, then multiply by 100. Formula: ((Starting − Current) ÷ Starting) × 100. Example: starting 200 lbs, now 175 lbs → ((200 − 175) ÷ 200) × 100 = 12.5%. Use the calculator above for instant results in lbs or kg.
How do you calculate percentage of weight loss in kg?
The formula is identical for kilograms: ((Starting kg − Current kg) ÷ Starting kg) × 100. Example: starting 90 kg, now 81 kg → ((90 − 81) ÷ 90) × 100 = 10%. Select the kg button in the calculator above and enter your weights in kilograms — the tool handles everything automatically.
What is a good weight loss percentage?
A loss of 5–10% of starting body weight is widely considered clinically significant — associated with meaningful improvements in blood pressure, blood sugar, and cholesterol. For most people, losing 1–2 lbs (0.5–1 kg) per week is a safe and sustainable rate. Reaching 5% is a meaningful milestone; 10% is an excellent achievement with measurable health benefits.
How do weight loss competitions calculate percentage?
Most weight loss challenge percentage calculator competitions — Biggest Loser format, office challenges, gym contests — use the standard formula: ((Starting − Current) ÷ Starting) × 100. Using percentage rather than absolute pounds makes the competition fair for participants of all sizes. The person with the highest percentage wins, not just the heaviest person who can afford to lose the most pounds.
How do I calculate weight loss percentage in Excel?
Place starting weight in A1 and current weight in B1. In C1 enter: =(A1-B1)/A1*100 for the percentage as a number, or =(A1-B1)/A1 and format as percentage. To track over time, keep the starting weight in A1 fixed (use $A$1) and update B1 each week. The formula =(($A$1-B1)/$A$1)*100 will always calculate from the original starting weight.
Is weight loss percentage the same as body fat percentage?
No. Weight loss percentage measures total body weight reduction relative to starting weight. Body fat percentage measures the proportion of your body that is fat tissue. When you lose weight, you lose a combination of fat, water, and muscle — not pure fat. Body fat percentage requires separate measurement tools like calipers or DEXA scans. This calculator measures overall weight loss percentage only.
How do I calculate body weight loss percentage for a child or infant?
The formula is the same for all ages, but the clinical context is very different for infants and newborns. Newborn weight loss is a normal physiological process in the first days of life, but requires careful monitoring — typically flagged when loss exceeds 7–10% of birth weight. For newborn weight loss calculations, see our dedicated newborn weight loss percentage calculator.
How do you figure percentage weight loss over multiple weeks?
Always calculate from your original starting weight, not from the previous week. Example: started at 200 lbs. After week 4 you weigh 188 lbs → ((200 − 188) ÷ 200) × 100 = 6% total loss. If you recalculate each week from the previous week's weight, the percentages do not add up correctly. Use the calculator above with your original starting weight each time for an accurate cumulative percentage.

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