Titan scores your HRV and resting heart rate against your own history. That history is your baseline, and the number of days it covers is the baseline window. This article explains how a baseline is built, which window each score uses, and how the Vitals and Battery ranges differ from the Recovery baseline.
01How Titan builds a baseline
A baseline is the median of your daily values across the window. Titan keeps one baseline for HRV and one for resting heart rate. The median is the middle value, so one unusual night moves it very little.
Titan calculates a baseline only when the window holds at least 7 days with readings and readings cover at least 60% of its days. A 7-day window therefore needs a reading on all 7 days. Until your data meets that bar, Recovery shows a rough estimate built from your raw HRV and resting heart rate.
02Window options and defaults
Onboarding asks for two windows, on the Recovery Baseline step and the Stress Baseline step. Each offers 7, 30, or 60 days. Recovery starts at 60 days and Stress starts at 30 days, and those values stay in place if you continue without changing them.
| Window | Recovery Baseline description | Stress Baseline description |
|---|---|---|
| 7 days | Most responsive to recent training stress and sleep changes | Fast stress detection after hard sessions |
| 30 days | Balanced trend window for most athletes | Balanced sensitivity for daily alerts |
| 60 days | Most stable baseline with minimal day-to-day noise | Smooth long-term stress trend comparisons |
A short window follows recent change quickly. A hard training block pulls a 7-day baseline down fast, so a tired week can still produce decent Recovery scores. A 60-day window holds your longer normal and shows a rough week as a drop.
03Where the windows are set
You choose both windows during onboarding. The current version has no Settings screen for changing them afterward. Recovery Preferences, at Settings > Recovery & Sleep > Recovery Preferences, controls your HRV source, RMSSD, and saved resting heart rates. It has no baseline control. Settings is reached from the avatar on Today, then You > Settings.
The Recovery help sheet in the app mentions a baseline period in Recovery settings. That control does not exist yet. If you need a different window, reach out through the contact page.
To see the window in use, open You and look at the HRV Baseline and RHR Baseline tiles under Your Fitness. Each tile shows your baseline value with a label such as "60 day baseline".
04Which baseline each score uses
| Score or screen | Baseline |
|---|---|
| Recovery score | Your Recovery window |
| HRV and resting heart rate comparisons on the Recovery screen | Your Recovery window |
| Stress headline and timeline on Today | Your Recovery window |
| Past Stress days, sleep stress, waking stress | Fixed 60-day baseline |
| Battery | Fixed 60-day HRV baseline |
| Vitals screen | The period you pick on that screen |
| Apple Watch app | 60-day default |
Recovery compares today's HRV and resting heart rate with the median and typical spread of your Recovery window. It also compares today with your last 7 days and adds your 30-day HRV variability. The Recovery score article covers the full model.
The Stress headline averages two ratios, your baseline HRV divided by current HRV and current resting heart rate divided by baseline resting heart rate. Titan subtracts 1, multiplies by 100, and clamps the result to 0 through 100. Both baselines come from your Recovery window. If they are unavailable, the Stress timeline falls back to 60-day baselines. Past Stress days and the sleep and waking averages always use 60-day baselines. See Stress score for how each Stress number is built.
Titan saves the Stress window you pick in onboarding. The Stress numbers you see come from the baselines in the table above, so the Stress window has no visible effect on them in normal use.
The Apple Watch app keeps its own settings and does not read the windows from your iPhone. It always scores against the 60-day default.
05How Vitals ranges differ
The Vitals screen shows HRV, resting heart rate, respiratory rate, and blood oxygen. It has its own period picker with 7D, 30D, 60D, and 6M options, and it opens on 30D. For each vital, the dashed baseline is the median for the selected period. The shaded range covers the 20th to 80th percentile of your daily values in that period.
Changing the period changes both the baseline and the range. It never changes Recovery. A vital needs at least 7 days of readings and 60% coverage in the period before Titan draws a baseline and range. The screen lists how many days were available and the coverage percent. Read more in Vitals.
06How the Battery band differs
Battery divides your recent average HRV by your 60-day HRV median. That 60-day baseline stays fixed whatever Recovery window you chose.
The shaded band on the Battery screen describes a different thing. It shows where the middle 60% of your Battery values fell at the same time of day over the previous 30 days, the 20th to 80th percentile. A day counts only with at least 75% coverage. Each time slot needs values from at least 11 of those 30 days. Gaps stay empty. The Battery article covers smoothing and sensitivity.
