Logging a weigh-in
Tap the Weight tab, then hit the + button in the top right corner. Enter your weight — and optionally your body fat percentage — then tap Save.
You can also edit or delete any past entry by tapping it in the history list below the chart. DayByDay keeps your full history, so nothing is ever lost.
Consistency beats precision
Weigh yourself at the same time each day — ideally first thing in the morning, after the bathroom and before eating. The absolute number matters less than logging at a consistent time.
Understanding the trend chart
The chart shows three layers of information at once. Each dot is an individual weigh-in — your raw data, exactly as you logged it. The amber line is your smoothed trend (a 7-day rolling average). The dashed purple line is your goal weight target.
The smoothed trend is the number that actually tells your story. Day-to-day weight can swing 2–5 lbs based on water retention, salt intake, and digestion — none of which represent real fat change. The trend line cuts through that noise.
Daily fluctuations are normal
Weight naturally fluctuates day to day — the trend matters more than any single reading. A single high number after a salty meal is not meaningful. Your trend over weeks is.
Changing the time range
Use the time range selector below the chart to zoom in or out. Options are 90 days, 6 months, 1 year, and All time.
Shorter ranges show more detail on recent fluctuations. Longer ranges show the bigger picture — which is often more motivating when progress feels slow week to week.
Body fat percentage
When you log a weigh-in, you can optionally add your body fat percentage. DayByDay tracks this as its own trend line and also calculates your lean mass and fat mass in pounds or kilograms.
This is especially useful if you're exercising regularly. You might see your scale weight plateau while your body fat percentage drops — which means you're losing fat and gaining muscle at the same time. That's a win the scale alone won't show you.
Goal date prediction
DayByDay calculates your estimated goal date based on your actual rate of loss from the past few weeks — not a generic formula. If you're losing 1.5 lbs/week on average, that's what the prediction is based on.
The prediction updates automatically as your trend changes. You'll also see a confidence range — a best-case and worst-case estimate — so you know it's a projection, not a promise.
New users
Goal date predictions need at least 2 weeks of data to be meaningful. Early on, they may swing quite a bit. Give it a few weeks and the estimate will stabilize.
Upcoming milestones
Below the chart, DayByDay shows your next upcoming milestones — things like 5% of your starting weight lost, 10% lost, halfway to your goal, and your goal weight itself. Each milestone shows an estimated date based on your current trend.
When you hit a milestone, the app celebrates. Confetti, a congratulations card, and a note in your history mark the moment. You earned it.
Weekly stats
- ✦High — your heaviest weigh-in this week
- ✦Low — your lightest weigh-in this week
- ✦Average — the mean of all your readings this week
- ✦Net change — how much your trend moved compared to last week
Importing your weight history
If you've been tracking your weight elsewhere, you can import your full history via CSV. Head to web.mydaybyday.app on any browser and use the Import tool.
The CSV format is simple: one column for the date (YYYY-MM-DD) and one for your weight in your preferred unit. See the Importing CSV files help article for the exact format and a template you can download.
Can I log more than one weigh-in per day?✦
Yes, but DayByDay uses the most recent entry for a given day in its trend calculations. If you log twice in one day, the second reading takes precedence.
What is BMR and why does it show here?✦
BMR stands for Basal Metabolic Rate — it's an estimate of how many calories your body burns at rest. DayByDay calculates it from your current weight, height, age, and sex. As you lose weight, your BMR changes, and seeing that helps you understand your metabolism over time.
How do I delete a weigh-in I logged by mistake?✦
Tap the weigh-in entry in the history list below the chart. An edit screen will open where you can correct or delete the entry.