What data the forecast uses
The goal-date forecast uses your logged weights (one entry per calendar day) and your goal weight from your profile.
It does not use calories, workouts, sleep, Garmin, or Strava data to compute the date. Those inputs feed other parts of the app, such as daily calorie balance and coaching.
How the date is calculated
Three steps, same rules every time:
Step 1: pick your recent weigh-ins
Take weigh-ins from the last 30 calendar days. Days without a log are skipped; gaps in logging are fine.
Step 2: fit a straight trend line
Run ordinary least-squares linear regression with calendar date on the x-axis and weight (kg) on the y-axis. In plain language: the line that best fits your recent points. There is no extra smoothing, outlier removal, or recency weighting in this step.
Step 3: extend the line to your goal
Where the trend line crosses your goal weight is your approximate goal date. The app also shows the fitted weekly rate in kg/week.
Worked example (synthetic data)
21 daily weigh-ins drifting down about 0.5 kg/week with small noise, goal 75 kg, reference date October 2, 2026: fitted rate -0.47 kg/week, approximate goal date December 25, 2026.
When you won't see a date
- Fewer than 3 weigh-ins in the last 30 calendar days.
- Your recent trend is flat or moving away from your goal.
- The projected date is more than 3 years away.
- You are already at (or within 0.05 kg of) your goal.
In those cases the app explains that the trend is not toward your goal instead of showing a date. Keep logging under the same conditions to build a clearer trend.
Why your date moves
Every new weigh-in changes the regression line. Water, salt, carbs, and timing shift single readings, so a few days of movement is normal. If the date drifts steadily over weeks, your recent pace has likely changed.
How accurate is it?
We do not yet have a validated accuracy figure, so we do not quote one.
Near-term projections tend to be more dependable than far-off ones, and more consistent weigh-ins steady the line. Real weight-loss paths often include plateaus and regain; a straight-line projection assumes your recent pace continues.
Research on individual weight trajectories (for example work summarized by NIH/NIDDK) shows that simple projections can mis-estimate long-run loss — which is why we treat the date as a planning aid, not a promise.
Known limitations
- A straight line assumes your recent pace continues; loss often slows over time.
- We show a single approximate date, not a statistical range.
- No adjustment for menstrual cycle, medication, or illness.
- Mixing morning and evening weigh-ins adds noise — pick a consistent time.
- Not medical advice.
How to get a steadier forecast
- Weigh at the same time (morning, after the bathroom, is a common choice).
- Log most days so the 30-day window stays filled.
- Keep your goal weight up to date in your profile.
- Give it at least 3 recent weigh-ins before expecting a data-based date.
FAQ
How does Weight Forecast calculate my goal date?▼
It fits a straight trend line (linear regression) through your weigh-ins from the last 30 calendar days and shows the approximate date that line reaches your goal weight. The date updates when you log a new weight.
How accurate is the goal date?▼
It is an estimate, not a guarantee. We have not published a measured accuracy figure yet. Projections a few weeks out are generally more dependable than ones many months away, and more consistent weigh-ins make the trend steadier.
How many weigh-ins do I need?▼
At least 3 weigh-ins within the last 30 calendar days. Two weeks or more of regular weigh-ins usually gives a steadier date.
Why don't I see a date?▼
Usually because there are not enough recent weigh-ins, your recent trend is flat or moving away from your goal, the projection is more than 3 years away, or you are already at your goal.
Why did my date change?▼
Each new weigh-in changes the trend line. Day-to-day water and food changes move single readings, so small shifts are normal. A steady drift over many days usually means your pace has really changed.
Does it use my calories, workouts, or Garmin data?▼
No. The goal-date forecast uses your logged weights and goal weight only. Calories, Garmin, Strava, sleep, and workouts appear elsewhere in the app (for example daily balance and coaching), but they do not change the trend-line date.
Morning or evening weight?▼
The forecast uses one weight per calendar day from your logged weigh-ins. Weigh at the same time each day for the most reliable trend.
Is the goal date calculated with AI?▼
No. The goal date is a statistical trend line (linear regression), not a machine-learning model. Some other features, such as voice or photo meal logging, may use AI separately.
Is this medical advice?▼
No. It is a planning estimate. Talk to a clinician about weight-loss goals, especially if you have a medical condition, are pregnant, or are under 18.
Want to try the projection without signing in? Use the goal weight date calculator to paste weigh-ins or plan from a weekly pace. To track daily and let the date update automatically, sign in free — no credit card.
Method version 1.0 (October 2, 2026). The goal-date forecast uses linear regression on weigh-ins from the last 30 calendar days. Not medical advice.