Losing weight is not just about eating less — it's about knowing how many calories your body actually needs and creating a smart, sustainable deficit. This weight loss target calculator for men uses the Mifflin-St Jeor equation — one of the most accurate resting metabolic rate formulas — to estimate your basal metabolic rate (BMR), total daily energy expenditure (TDEE), and a daily calorie target matched to your activity level and chosen deficit.
It also projects your weekly weight loss, the time needed to reach your goal weight, and a protein range that helps preserve lean muscle. Built for adult men who want an evidence-informed starting point, this tool is useful for planning a fat-loss phase, complementing a fitness app, or setting realistic expectations before changing your diet.
Enter your age, height, current and target weight, activity level, and preferred daily deficit. The calculator displays the whole picture at a glance, so you can adjust your plan with confidence.
⚙️ Personal Details
📊 Results
How to Use This Tool
Start by entering your age, height, current weight, and target weight. Choose the units that match your scale or tape measure, then select your typical activity level. The calculator uses the Mifflin-St Jeor equation to estimate how many calories your body burns at rest and then scales that number by your activity multiplier to estimate total daily energy expenditure (TDEE). Finally, pick a daily calorie deficit — mild, balanced, or aggressive — and see your recommended intake, projected weekly loss, and estimated time to goal.
- Enter your age and height.
- Enter current and target weight (kg or lb).
- Choose activity level.
- Choose daily calorie deficit.
- Press Calculate and review the results.
The Formula Explained
For men, the Mifflin-St Jeor equation estimates basal metabolic rate as:
BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5
Total daily energy expenditure is then TDEE = BMR × activity multiplier. The activity multipliers follow standard conventions: sedentary = 1.2, lightly active = 1.375, moderately active = 1.55, very active = 1.725, athlete = 1.9. This is one of the most widely cited predictive equations for healthy adults, though individual variation exists. See the Mifflin-St Jeor equation on Wikipedia for background.
Worked Example
A 40-year-old man, 180 cm and 95 kg, moderately active, wants to reach 85 kg.
BMR = 10 × 95 + 6.25 × 180 − 5 × 40 + 5 = 1,830 kcal
TDEE = 1,830 × 1.55 ≈ 2,837 kcal
With a balanced 500 kcal/day deficit, daily target ≈ 2,337 kcal, weekly loss ≈ 0.45 kg, and time to goal ≈ 10 kg ÷ 0.45 ≈ 22 weeks.
Activity Multiplier Reference
| Activity Level | Example | Multiplier |
|---|---|---|
| Sedentary | Desk job, little exercise | 1.2 |
| Lightly active | 1–3 workouts/week | 1.375 |
| Moderately active | 3–5 workouts/week | 1.55 |
| Very active | 6–7 workouts/week | 1.725 |
| Athlete | Hard daily training | 1.9 |
Common Mistakes to Avoid
- Setting a target weight below a reasonable BMI range. Use a healthy target for your height.
- Choosing too large a deficit. Aggressive plans can cause muscle loss and fatigue.
- Ignoring protein. A range of 1.6–2.2 g per kg of body weight helps preserve muscle.
- Not adjusting as you lose weight — maintenance calories fall as body mass drops.
Frequently Asked Questions
Why does the projected date use 7,700 kcal per kg? This is a common approximation: one kilogram of body fat contains roughly 7,700 kcal of energy. Real fat loss is not perfectly linear, so treat the date as an estimate.
Can I use a bigger deficit to speed things up? A larger deficit does increase weekly loss on paper, but it also raises the risk of muscle loss, cravings, and metabolic slowdown. Most guidelines recommend a deficit of 300–500 kcal/day.
Do I need to count calories forever? No. Many people use a tool like this for a few weeks to recalibrate portion sizes, then maintain with conscious eating patterns.
For evidence-based guidance, see the NIDDK weight management guide and the CDC page on balancing calories.