Calorie Deficit Calculator
Compare an estimated adult maintenance intake with a fixed daily deficit derived from a selected weekly weight-change illustration.
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What this calculator estimates
Compare an estimated adult maintenance intake with a fixed daily deficit derived from a selected weekly weight-change illustration. The result is a simplified calculation, not a prediction of actual weight loss.
Inputs and calculation method
Enter age, equation option, centimetres, kilograms, activity level and a weekly loss option of 0.25, 0.5 or 0.75 kg. The tool estimates maintenance with Mifflin–St Jeor × activity, then subtracts the selected weekly amount multiplied by 7,700 and divided by seven.
Formula and units
Estimated maintenance = Mifflin–St Jeor resting kcal × activity factor. Daily deficit = selected kg/week × 7,700 ÷ 7. Displayed intake comparison = maintenance − daily deficit. The three options imply 275, 550 or 825 kcal/day respectively.
How to use it
- Enter adult age, equation option, height in cm and weight in kg.
- Choose an activity level representing your usual overall week.
- Select a weekly loss option to see the corresponding fixed deficit.
- Check the comparison for suitability rather than assuming every calculated intake is appropriate.
Worked example
Age 35, 165 cm, 70 kg, the female equation and Moderate activity (1.55) give estimated maintenance of 2,163 kcal/day. The 0.5 kg/week option subtracts 550 kcal/day, displaying about 1,613 kcal/day. Choosing 0.25 instead subtracts 275 and displays about 1,888 kcal/day.
How to read the result
The weekly option is converted to a fixed energy deficit. Real weight changes are not linear, and this tool does not model metabolic adaptation or establish a safe minimum intake.
Common mistakes
- Assuming the selected weekly rate will occur exactly.
- Overstating activity to create a more comfortable intake estimate.
- Following a very low result merely because the calculation produced it.
Method limitations
This adult planning model is unsuitable for children’s growth, pregnancy, breastfeeding or clinical nutrition planning. Although the form can accept younger ages, the equation and deficit presets do not validate a diet for them. Body weight and energy expenditure change over time.
Sources and method references
Supporting guides for this calculator
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Calorie Deficit Calculator FAQs
Is this the same as the Calorie Calculator’s deficit?
No. Here the deficit comes from the selected weekly option; other pages may show a different fixed illustrative subtraction.
Will I lose the selected amount each week?
No. The 7,700-kcal/kg conversion is a simplifying assumption and does not predict adaptation or water-weight changes.
Does it prevent an unsuitable intake?
No personalised minimum-intake or medical assessment is performed. A numerical result does not establish suitability.
Using the estimate
Use the output to understand the energy arithmetic behind a selected deficit. Assess a sustainable, adequate intake with more context than this fixed model supplies.
Keep the deficit nutritionally practical
A calorie deficit changes the energy budget, so use a fibre reference as another check when planning food choices.