Weight Tracker
Log your weight as often as you like and see the real trend behind the daily ups and downs. The chart smooths your weigh-ins with a 7-day moving average, calculates how fast you are losing or gaining per week, and projects when you will reach your goal weight.
Last updated:
Add at least two weigh-ins to see the chart.
Your log is saved in this browser only. Download a CSV now and then as a backup. CSV import accepts columns date, weight and optional note (dates as YYYY-MM-DD or MM/DD/YYYY); add "lb" or "kg" in the weight header or values to set the unit.
How to use the Weight Tracker
- Pick your units (kg or lb) and optionally type a goal weight. The page opens with example data so you can see how it works.
- Add a weigh-in: the date defaults to today. Type your weight, add a note if you like and press Add weigh-in. The example data is replaced by your log.
- Read the trend: the green line is your 7-day average and the Trend card shows your rate of change per week.
- Check the goal date: with a goal set, the dotted projection line and the Projected goal date card show when the current trend reaches it.
- Back up or move your data with Download CSV, or bring in weigh-ins from a spreadsheet or another app with Import CSV.
How the trend and projection are calculated
7-day moving average for a day d = the mean of all weigh-ins dated from d − 6 to d. It removes most of the day-to-day water swings.
Trend per week: the tracker fits a least-squares line w = a + b·t through the weigh-ins in the chosen window (days t, weights w), where
b = (n·Σtw − Σt·Σw) ÷ (n·Σt² − (Σt)²), and the weekly rate is 7 × b.
Projected goal date = latest weigh-in date + (goal − trend value today) ÷ b days. If the trend is moving away from your goal, the tracker says "Not on track" instead of inventing a date.
Weekly rate reference
How long a change takes at a steady weekly rate (1 kg = 2.2046 lb):
| Rate per week | Per month (≈4.35 weeks) | Time to change 5 kg (11 lb) | Time to change 10 kg (22 lb) |
|---|---|---|---|
| 0.25 kg (0.55 lb) | 1.1 kg (2.4 lb) | 20 weeks | 40 weeks |
| 0.5 kg (1.1 lb) | 2.2 kg (4.8 lb) | 10 weeks | 20 weeks |
| 0.75 kg (1.65 lb) | 3.3 kg (7.2 lb) | about 6.7 weeks | about 13.3 weeks |
| 1 kg (2.2 lb) | 4.4 kg (9.6 lb) | 5 weeks | 10 weeks |
Tips for a trend you can trust
- Weigh in at least 3 to 4 times a week; daily is best for a smooth average.
- Use the same scale on a hard, level floor.
- Judge progress by the 7-day average over two or more weeks, not by a single day.
- Expect jumps after salty meals, travel, hard workouts or the menstrual cycle. They usually fade within a few days.
- Use the note field to record things like a new routine, so you can spot what changes the trend.
Frequently asked questions
Why does my weight change so much from day to day?
Daily weight can swing by 0.5 to 2 kg (1 to 4 lb) because of water, salt, carbohydrate stores, food still being digested and the time of day. These swings hide the slower change in body fat. That is why the tracker shows a 7-day moving average and a trend line, which move much more steadily than single weigh-ins.
How is the 7-day moving average calculated?
For each weigh-in, the tracker averages every weigh-in from that day and the six days before it. If you skip days, it simply averages the ones you logged in that 7-day window. A rising or falling average over a couple of weeks is a far better sign of real change than any single number.
How is the weekly trend and goal date calculated?
The tracker fits a straight line (least-squares linear regression) through your weigh-ins in the chosen window, 4 weeks by default. The slope of that line times 7 is your trend per week. The projected goal date is when that line reaches your goal weight. It assumes your current rate continues, so treat it as an estimate that updates as you log more.
What is a realistic rate of weight loss?
Many health organizations describe a gradual loss of about 0.5 to 1 kg (1 to 2 lb) per week as a reasonable pace for most adults. Faster loss is common in the first week or two as water weight drops. If you have health conditions or a large amount to lose, a doctor or dietitian can help set a safe target.
When is the best time to weigh myself?
Weigh at the same time and in the same conditions each day, for example right after waking up and using the bathroom, before eating or drinking, in similar clothing. Consistency matters more than the exact time, and frequent weigh-ins make the moving average more reliable.
Can I import data from another app or a spreadsheet?
Yes. Save it as a CSV with a date column and a weight column (and optionally a note). Dates can be YYYY-MM-DD or MM/DD/YYYY. If the weight header or values contain lb or kg the unit is detected; otherwise your current unit is used. Imported rows are merged with your log, and a date that already exists is updated.
Where is my weight data stored?
Only in this browser's local storage on this device. There is no account and nothing is sent to a server. Clearing your browser data deletes it, so use Download CSV now and then to keep a backup.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.