Weight Tracker: Free Weight Logging Calculator

What is a weight tracker?

A weight tracker is a tool for recording body weight over time and viewing the pattern as a graph. This weight logging calculator saves each entry — a date, a weight, and an optional note — directly in the web browser. It then works out statistics such as the average, the lowest and highest recorded weight, and the net change over a chosen date range.

The tool does not require an account or an internet connection to use after the page has loaded. Every entry stays on the device that created it.

How to log a weight entry

1. Pick a date. It defaults to today but can be changed to log a past weigh-in.
2. Enter the weight in kilograms. The field accepts values greater than 0 and up to 500 kg, in steps of 0.1 kg.
3. Add an optional note, such as "after workout" or "travel day."
4. Select "Add Entry."

The entry then appears in the weight history table and in the trend graph. An entry is rejected, with an error message, if the weight field is left blank, is zero or negative, or exceeds 500 kg.

Weight statistics and how they are calculated

The statistics panel covers only the entries that fall inside the selected start and end date. By default, that range is the most recent 30 days, but it can be widened or narrowed with the "Start Date" and "End Date" fields.

Average weight

Average weight is the sum of the weight values in the selected range divided by the number of entries in that range. It is rounded to one decimal place.

Minimum and maximum weight

These are simply the lowest and highest single weight values recorded inside the selected range.

Weight change

Weight change compares the earliest and latest entries in the selected range by date, not by the order the entries were typed in. If a missed day is logged later, it is still placed by its date, not by when it was added.

A positive number means weight went up over the period. A negative number means it went down.

Example

Suppose four entries fall inside the selected date range:

• Average: (82.4 + 81.9 + 81.2 + 80.6) ÷ 4 = 326.1 ÷ 4 = 81.525, rounded to 81.5 kg
• Minimum: 80.6 kg
• Maximum: 82.4 kg
• Weight change: 80.6 − 82.4 = −1.8 kg (a loss of 1.8 kg over the three weeks)

Reading the weight trend graph

The graph plots every entry in the selected date range as a point on a line, ordered from the earliest date to the latest. A line sloping down shows weight loss over that stretch. A line sloping up shows weight gain. A flat line shows a stable weight. The graph redraws automatically each time an entry is added, edited, or removed, or when the date range changes.

Weight history and date filtering

Every logged entry, regardless of date range, appears in a history table below the graph. The table can be sorted with the newest entry first or the oldest entry first, and it shows the date, weight, and any note attached to each entry. An entry can be removed with the delete button, which asks for confirmation before the entry is permanently erased. Deleting an entry recalculates every statistic and redraws the graph.

The date-range filter above the statistics panel affects only the statistics and the graph, not the history table, so old entries stay visible even after they fall outside the selected range.

Normal day-to-day weight fluctuation

Body weight commonly moves by 1 to 2 kg from one day to the next without reflecting any real change in body fat. Causes include the amount of food and fluid still in the digestive system, water retained from meals high in salt or carbohydrate, and normal hormonal cycles. Because of this, a single day's reading can be misleading. Looking at the average over a week or more, using the statistics panel, gives a steadier picture than comparing two individual days.

Frequently asked questions

How often should weight be logged? Daily logging gives the most data for trend analysis, but weekly logging at the same time of day also works, since the tool measures change based on date, not on how often entries are added.

What is the best time of day to weigh in? Most people get the most consistent readings first thing in the morning, after using the bathroom and before eating or drinking.

Why does my weight change so much day to day? Short-term shifts of 1 to 2 kg are usually water, food, and waste, not fat gain or loss. The average and trend graph filter out most of this noise.

Can this tool track weight gain instead of loss? Yes. The statistics and graph work the same way regardless of the direction of change; a positive weight-change value simply means the later date weighed more than the earlier one.

Is the logged weight data private? Yes. Entries are stored only in the browser's local storage on the device used to enter them. Nothing is sent to a server. Clearing the browser's site data or switching devices removes access to the log, so entries do not sync between devices.

Does the tool support pounds instead of kilograms? Weight is entered and displayed in kilograms only. To log a value measured in pounds, convert it first: 1 kg is about 2.2 lb.

How is an incorrect entry fixed? Delete the wrong entry from the history table and add a new one with the correct date and weight. All statistics update immediately.