Calorie Deficit Calculator

Calorie Deficit Calculator

Calorie Deficit Calculator works backwards from a goal. Enter your current weight, your target weight, and the date you want to reach it, and it tells you the daily calorie deficit that implies, along with a daily intake target.

How to use it

1. Enter your current weight and your goal weight. Switch between lbs and kg with the toggle.
2. Set the target date.
3. Enter your maintenance calories (TDEE) if you know it.
4. Read the required daily deficit and the resulting daily intake.

Where the numbers come from

The standard estimate is that a pound of body fat represents roughly 3,500 calories. Losing a set number of pounds by a set date gives a total deficit, and dividing it by the number of days gives the daily figure.

This is a planning estimate, not a physical law. Metabolic rate falls as you lose weight, water weight moves the scale by several pounds independently of fat, and the 3,500 figure is an approximation. Treat the output as a starting point to adjust from, not a prescription.

Worked example

When it helps

• Checking whether a goal date is realistic before committing to it.
• Seeing what moving the deadline out by a month does to the daily target.
• Turning a vague intention into a specific daily number.
• Sanity-checking a target someone else has set for you.

Common mistakes

• Setting a deadline that requires an extreme deficit. Very large deficits are hard to sustain and cost muscle as well as fat.
• Treating TDEE as fixed. It falls as you lose weight, so the same intake produces a smaller deficit over time.
• Reading day-to-day scale movement as fat change. Most of it is water and food in transit.

What this tool handles

• This is a general fitness estimate and not medical advice. Talk to a doctor before starting a significant calorie deficit, particularly if you have any medical condition.