Calculator
Example Data Table
| Starting | Current | Timeframe | Loss | Loss % | Avg / week |
|---|---|---|---|---|---|
| 92 kg | 87 kg | 4 weeks | 5 kg | 5.43% | 1.25 kg/week |
| 180 lb | 171 lb | 6 weeks | 9 lb | 5.00% | 1.50 lb/week |
| 75 kg | 76.5 kg | 3 weeks | -1.5 kg | -2.00% | -0.50 kg/week |
Your Calculation History
Progress Graph
Formula Used
- Weight loss: Loss = Starting − Current
- Loss percentage: (Loss ÷ Starting) × 100
- Percentage change: ((Current − Starting) ÷ Starting) × 100
- Pace per week: Loss ÷ Weeks (Weeks derived from timeframe)
- BMI (optional): Weight(kg) ÷ Height(m)2
How to Use This Calculator
- Enter your starting and current weights.
- Choose the correct unit (kg or lb).
- Optionally add a timeframe to estimate weekly pace.
- Optionally add height to see BMI change and categories.
- Optionally add a goal weight to measure distance.
- Press Calculate. Results appear above the form.
- Use Download CSV or Download PDF to export.
What the Percentage Represents
Weight-loss percentage standardizes progress against your starting weight. The calculator uses (Starting − Current) ÷ Starting × 100. For example, moving from 92 kg to 87 kg is 5 ÷ 92 × 100 = 5.43%. Standardization makes two people comparable even when their starting weights differ. A 5 kg change is 6.67% from 75 kg, but only 5.00% from 100 kg.
Interpreting Weekly Pace
When you add a timeframe, the tool converts it to weeks (days ÷ 7, months × 4.34524). Pace equals total loss ÷ weeks, plus a percent-per-week pace. If 9 lb is lost over 6 weeks, the average pace is 1.50 lb/week and 0.83%/week from the original 180 lb. Use pace to compare periods with different lengths and identify slowdowns.
Unit Conversion Accuracy
Calculations run in kilograms for consistency, then display in your chosen unit. Pounds convert using 1 lb = 0.45359237 kg. That constant keeps exports auditable and prevents rounding drift. If you switch units, your history chart remains consistent because values are stored in kilograms and converted only for display.
Using BMI for Context
With height provided, the calculator estimates BMI using Weight(kg) ÷ Height(m)² and shows standard categories: under 18.5, 18.5–24.9, 25.0–29.9, and 30.0+. Example: at 1.70 m, 92 kg yields BMI 31.8, while 87 kg yields 30.1, a change of −1.7 points.
Goal Distance Planning
Goal distance equals Current − Goal. A positive value means you are above your goal and still need to lose weight; a negative value means you are below it. If current weight is 87 kg and goal is 82 kg, distance is 5 kg. Combine distance with weekly pace to estimate how long a plan might take. At 0.8 kg/week, 5 kg corresponds to about 6.25 weeks.
Exporting and Auditing Results
CSV exports include timestamps, weights, percentage change, and optional BMI values for tracking in spreadsheets. PDF exports capture the latest results plus your recent history for sharing with a coach or clinician. Keeping a small rolling log (up to 30 entries) supports consistency checks and highlights plateaus, rebounds, and measurement variability. Record under similar daily conditions.
FAQs
How is weight loss percentage calculated?
The tool subtracts current weight from starting weight, then divides by starting weight and multiplies by 100. A positive value means net loss; a negative value indicates overall gain.
Why does the calculator show both loss percentage and percentage change?
Loss percentage is framed as progress from the start (positive for loss). Percentage change uses (Current − Starting) ÷ Starting × 100, so loss appears as a negative value. Seeing both reduces misinterpretation.
What timeframe should I enter for pace?
Enter the number of days, weeks, or months between your starting and current measurements. The calculator converts to weeks and reports average change per week, which helps compare different tracking periods.
Do I need height to use this calculator?
No. Height is optional and only used to estimate BMI changes. If you do enter height, results include BMI at start and current weights plus standard category labels for context.
Can I export my results?
Yes. CSV downloads your saved history for spreadsheet tracking. PDF creates a printable report of your latest calculation and history table, useful for sharing progress summaries.
Why might my chart look inconsistent?
Daily weight fluctuates due to water, meals, and timing. Record under similar conditions for cleaner trends. If you entered different units on different days, the chart remains consistent because values are stored in kilograms.