How this calculator works
Adult maintenance energy comes from the current EER equations. A user-selected surplus is added; the 300 kcal default is within the NHS example range of 300 to 500 extra kcal/day for gradual adult gain. An optional goal adds a user-entered energy adjustment and schedules a date using the entered weekly pace. The pace and calorie adjustment are independent assumptions. The date is arithmetic, not a prediction: metabolism, water and tissue composition change over time. No fixed kcal-per-kg rule is used. Unintentional weight loss warrants assessment rather than relying on an online budget. The result is an estimate for information only and is not medical advice.
Formula
Scenario kcal/day = maintenance EER + entered surplus. Scheduled weeks = (target kg - current kg) / assumed kg per week. Goal date = start date plus the rounded-up number of days.
Worked example
At maintenance 2520.17 kcal/day, a 300 kcal surplus gives 2820.17 kcal/day. A 5 kg increase at an assumed 0.25 kg/week schedules 20 weeks, or 140 days.
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Frequently asked questions
Will the date predict my actual weight?
No. It is a schedule at your assumed constant pace, not a physiological forecast.
How is the daily energy estimate calculated?
Health Canada's 2023 adult EER equations use age, sex, height, weight and whole-day activity.
Can I use this during pregnancy or illness?
No. These planning scenarios are for healthy, non-pregnant adults; specialised nutrition needs individual care.