Weight Loss Calculator

Calculate how long to reach your target weight with milestones and daily calorie deficit.

Last updated: April 2026 · Source: NHS — 12 tips to help you lose weight

You'll Reach 75kg By

29 August 2026

20 weeks (4.6 months) · Lose 10.0kg total

Daily Calorie Deficit

550 kcal

Weekly Loss

0.5 kg

Milestones

25% done

82.5 kg

Week 5

50% done

80.0 kg

Week 10

75% done

77.5 kg

Week 15

100% done

75.0 kg

Week 20

NHS recommends 0.5-1kg per week for safe, sustainable weight loss. Faster rates may lead to muscle loss and are harder to maintain.

Disclaimer

This calculator is provided for informational purposes only and should not be considered as financial or tax advice. All calculations are performed locally in your browser — no personal data is collected or sent to our servers. Rates and thresholds are sourced from HMRC and GOV.UK and are updated for the current tax year. Always verify results with HMRC or consult a qualified professional before making financial decisions.

How It Works

This calculator works out the daily calorie deficit needed to reach your target weight by a chosen date. One kilogram of body fat stores approximately 7,700 kcal, so a deficit of 500 kcal per day produces roughly 0.5 kg of weight loss per week. The NHS recommends a safe rate of 0.5–1.0 kg per week.

The calculator estimates your Total Daily Energy Expenditure (TDEE) using the Mifflin-St Jeor equation and your activity level, then subtracts the required daily deficit. It flags any target that requires a deficit larger than 1,000 kcal per day or a calorie intake below 1,200 kcal (women) or 1,500 kcal (men), as these can be unsustainable.

Enter your current weight, target weight, goal date and activity level. The calculator shows daily calories, expected weekly loss rate and whether the timeline is realistic. Extending the deadline by a few weeks can often make the difference between a healthy deficit and an extreme one.

Example: 90 kg to 80 kg in 20 weeks, moderately active male

  1. Weight to lose: 10 kg (77,000 kcal total deficit)
  2. Daily deficit needed: 77,000 ÷ 140 days = 550 kcal/day
  3. TDEE estimate: 2,650 kcal
  4. Daily calorie target: 2,650 − 550 = 2,100 kcal
  5. Expected rate: ~0.5 kg/week (healthy range)

Source: NHS — 12 tips to help you lose weight

Frequently Asked Questions

What does the Weight Loss Calculator do?
Calculate how long to reach your target weight with milestones and daily calorie deficit. All calculations are performed in your browser using official UK rates and thresholds.
Is this medical advice?
No. This calculator is for informational purposes only and does not constitute medical advice. Always consult your GP or an appropriate healthcare professional for medical guidance.
Are the reference values from the NHS?
Where applicable, this calculator uses reference values and guidelines from the NHS and other UK health authorities. Individual needs may vary based on personal health circumstances.