Trend Weight Calculator
Paste your weigh-ins or load an export from Apple Health, Withings, Google Fit, Happy Scale, Libra or openScale. The calculator smooths out the daily ups and downs exactly like the Trendcurve app and shows you where your weight is really heading.
Your data never leaves your browser
The calculation runs entirely on your device. No upload, no account and nothing stored on our server.
Order and separators don't matter, comma or dot as decimal mark. Several weigh-ins on the same day are averaged.
Drop a file here or
Apple Health (export.zip or export.xml), Withings (weight.csv or ZIP), Google Fit (Takeout CSV), Happy Scale, Libra, openScale, Trendcurve and any CSV with a date and a weight column.
Your result Example data
This is made-up example data covering twelve weeks, so you can see what a result looks like. Paste your own weigh-ins above.
Goal date (projection)
Share as an image
Create an image of your curve for Instagram, WhatsApp and the like. It is made in your browser.
Automatic in the app, every day
Trendcurve recalculates your trend after every weigh-in, can read your weight from Apple Health and imports your history from Happy Scale, Libra, openScale or Excel. Trend, weekly rate and the choice of method are free; the forecast with a goal date is part of Pro.
What is trend weight?
Your weight goes up and down by one to two kilos (two to four pounds) from day to day without any change in body fat. Water, salt, carbs, digestion and your cycle all move the number on the scale. Trend weight smooths out this noise and shows where your weight is actually heading.
By default the calculator uses exponential smoothing: every new weigh-in pulls the trend 10 percent of the way towards it, and older values fade out gradually. You can also choose a 7-day or 14-day moving average or double exponential smoothing (Holt).
How to read the chart
- The grey dots are your daily weigh-ins. Their ups and downs are noise, neither progress nor a setback.
- The blue line is your trend. Only its direction over several weeks matters.
- The weekly rate is the slope of the trend over the last 14 days. For weight loss, many experts consider 0.5 to 1 percent of body weight per week sustainable.
- The typical daily fluctuation tells you how far a single weigh-in can stray from the trend without anything having happened.
How to export your data
- Apple Health
- Open the Health app, tap your profile picture in the top right and then "Export All Health Data". You can load the resulting export.zip right here, even if it is several hundred megabytes.
- Withings
- In the Withings web dashboard you can download your data from the settings. Load the ZIP or the weight.csv inside it.
- Google Fit
- Export your Fit data with Google Takeout. The daily activity metrics file contains a weight column; load it or the whole ZIP.
- Health Connect
- Health Connect has no CSV export of its own. If an export app saves your values as CSV, the calculator detects the date and weight columns automatically.
- Happy Scale, Libra, openScale
- Export your data as CSV in the app and load the file here.
- Excel and other spreadsheets
- Save the sheet as CSV. One column with the date and one with the weight is enough; comma or semicolon as separator both work.
How the calculator works
The calculator uses the same chain of calculations as the Trendcurve app: several weigh-ins on one day are averaged. Exponential smoothing uses a factor of 0.1 and starts as a running mean so the first value doesn't dominate the trend for weeks. Across gaps the factor is scaled up to the number of days that have passed. Holt weights the level at 0.15 and the direction at 0.1 and damps the direction by 0.95 per day.
The weekly rate is the slope of a regression line through the trend values of the last 14 days. It appears from 7 days with a weigh-in, at least 4 of them within that period. The typical daily fluctuation is the standard deviation of daily weigh-ins from the trend over the last 90 days. All values refer to your last day with a weigh-in.