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Energy

Calorie deficit and weight-loss planner

Compare intake scenarios and model time to a lower goal weight.

Free · No account neededMethod & sources

YOUR INPUTS

Your measurements

Measurement units
Energy units

The source equations are published separately for males and females. Choose the category the equation uses.

Accepts ages 18 to 85.

Daily energy divided by resting energy. Use a value from 1.4 to 2.3. How to choose an activity level

Inputs stay in this browser.

YOUR RESULT

Start with your numbers.

Compare intake scenarios and model time to a lower goal weight. Complete the fields to see the calculation, method, and limits.

UNDERSTAND THE METHOD

How to use this calculator

Enter current and goal weight, activity, and an intake scenario. The table compares 100-kcal steps. Change the intake field to inspect a different trajectory. This model changes energy needs over time.

What the result can tell you

This adult model is not for pregnancy or breastfeeding. It assumes fixed activity and carbohydrate at 50% of energy. It cannot predict adherence or individual physiology. Calorie floors limit displayed scenarios; they do not establish personal safety.

Common questions

What does the intake scenario table compare?

It compares intake steps of 100 kcal and models a trajectory for each scenario. Change the intake field to inspect another scenario as estimated energy needs change over time.

Is the displayed calorie floor a safe personal intake?

No. The floor only limits the scenarios shown. This adult model cannot predict adherence or individual physiology and is not for pregnancy or breastfeeding.

Sources & limitations2 sources

Sources checked September 12, 2026. These notes identify methods and assumptions. They have not received an independent clinical review.

  1. Dynamic energy-balance model from Hall and colleagues.pmc.ncbi.nlm.nih.gov
  2. Body-fat estimate used to initialize the model.pubmed.ncbi.nlm.nih.gov