Weekly Weight Loss Rate Calculator

How it is calculated

The tool averages your loss over the elapsed time. weekly rate = (start − current) ÷ weeks elapsed and percent per week = weekly rate ÷ start weight × 100. Weights can be pounds or kilograms; the unit is lb or kg (left empty it means lb, and any other value gives no result), and the label on the rate follows that choice. Start weight, current weight and weeks elapsed must all be above zero. The safety message is based only on the percentage: up to 1 % of the starting weight per week is shown as within the commonly recommended range, above 1 % as faster than that range, and a negative rate as weight gained (the rate is then printed with a minus sign). No change at all counts as within range. The 1 % limit is a fixed threshold and does not look at age, health or starting body fat. It averages the whole period, so it hides weeks of faster or slower loss.

Common mistakes

• Counting the weigh-in date as week zero and entering one week too many, or too few; weeks elapsed should be the full gap between the two weigh-ins.
• Comparing against a 1–2 lb rule when the tool judges against 1 % of starting weight: a heavier person can lose more pounds per week and still be rated within range, while 200 lb dropping 10 lb in 4 weeks (1.25 %) is flagged as fast.
• Entering weeks as days (for example 56 instead of 8), which shrinks the rate seven-fold.
• Entering the starting weight and current weight in different units, or leaving the unit on lb when the numbers are kg; the rate and its label are then wrong.
• Using two weigh-ins taken at different times of day or after a high-sodium meal; water shifts can distort a short period dramatically.