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Weight Loss Calculator
See your weight loss in stone, pounds, kg and %, plus timeline projections with target dates.
Calculate Your Weight Loss
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How to Use This Calculator
Enter your current weight and target weight in stone and pounds (or kg), then choose your weekly loss rate. The calculator instantly shows your total weight loss in all four units simultaneously (stone, pounds, kg and %), plus a timeline with your projected target date.
Unlike some sites, this tool is completely free with no signup. Your data never leaves your browser.
Weight Loss Rate Reference Table
| Weekly Rate | Time per Stone | Daily Deficit | NHS Verdict |
|---|---|---|---|
| 0.5 lb/week | 28 weeks | 250 kcal | ✅ Gentle |
| 1 lb/week | 14 weeks | 500 kcal | ✅ Recommended |
| 1.5 lb/week | ~9 weeks | 750 kcal | ✅ Safe |
| 2 lb/week | 7 weeks | 1,000 kcal | ⚠️ Upper safe limit |
What the NHS Says
The NHS recommends losing 1 to 2 lb (0.5 to 1 kg) per week through a calorie deficit of 500 to 1,000 kcal per day. They also suggest an initial target of 5 to 10% of body weight, which delivers significant health benefits even before reaching your ultimate goal.
For personalised support, ask your GP about NHS weight management services, including Tier 3 specialist programmes. These are free and include dietitian, psychological, and medical support.
Frequently Asked Questions
How do I calculate weight loss in stone and pounds?
Enter your starting weight and current weight in stone and pounds. Subtract to get your loss, then divide by your starting weight and multiply by 100 for the percentage. Our free calculator above does this instantly in stones, pounds, kg, and percentage simultaneously.
How long will it take to lose 2 stone?
At 1 lb per week: 28 weeks. At 1.5 lb per week: 19 weeks. At 2 lb per week (upper NHS safe limit): 14 weeks. Use the calculator above and select your weekly rate to see your personal target date.
What is a safe rate of weight loss?
The NHS recommends 1 to 2 lb (0.5 to 1 kg) per week. Faster than 2 lb per week increases risks including gallstones, muscle loss, and nutrient deficiency. Our calculator flags rates above the NHS safe range.
How many calories do I need to lose 1 lb per week?
One pound of fat stores about 3,500 kcal. To lose 1 lb per week, you need a daily deficit of 500 kcal through eating less, moving more, or both. For 2 lb per week, the deficit is 1,000 kcal per day.
What percentage of body weight should I aim to lose?
The NHS suggests an initial target of 5 to 10% of body weight, which delivers significant health benefits. For a 15-stone person, 5% is 10.5 lb and 10% is 21 lb (1.5 stone).
Is this weight loss calculator free?
Yes, completely free with no signup required. Unlike some competitors, we never gate our tools behind trials or accounts. Your data stays in your browser and is never sent to our servers.
How accurate are weight loss timeline predictions?
Timelines are estimates based on the 3,500 kcal per pound rule. Actual loss varies with body composition, metabolic adaptation, water fluctuations, and adherence. Use predictions as a guide, not a guarantee. Weekly weigh-in trends matter more than any single prediction.
Should I weigh myself daily or weekly?
Weekly weigh-ins (same day, time, and conditions) give the clearest trend. Daily weighing works if you focus on the 7-day average rather than individual readings, as daily weight can fluctuate 1-3 lb from water, food, and hormones.
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Maintaining Weight Loss
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Reviewed by the StoneToKg editorial team. Last updated October 2026. Calculator estimates based on 3,500 kcal per pound. For personalised advice, consult your GP.