Getting started
- Connect Apple Health. Splitcast asks to read workouts, heart rate, VO2max, HRV, running power and sleep. Allow all of them for the best results.
- Wait for the first read. Splitcast reads up to 5 years of history once. With a lot of workouts this can take a minute; after that it opens straight away.
- Pick your races. Splitcast lists your fastest runs at each distance. Tick the ones that were races or hard efforts. Pick a few at different distances if you can.
- Compare and set a goal. Compare shows then vs now for any race. Goal tracks your predicted time towards a target.
Predictions
Why does it say "Nothing to predict from yet"?
Predictions start from one real result: a race, parkrun or hard solo effort. Add one in Results, or tick one of your fast runs. Until then, Goal shows a rough estimate from your fastest mile in the last 8 weeks.
My prediction seems too fast or too slow
Check "How good is this?" on the Goal tab to see how accurate it has been for you. Common causes: a race on a downhill or short course (swipe it in Results to stop it being used), a hilly race used as the benchmark (predictions assume a flat course), or a marker with odd data (turn it off in Results › Prediction markers).
Why is my marathon prediction slower than other calculators?
Most calculators assume everyone slows down by the same amount over longer races. When you have races at two distances within a year, Splitcast uses how you actually slow down, which for most people is more than the textbook figure.
A marker says "Not enough data"
Each marker needs a minimum amount of data in the window: a VO2max reading from the Watch in the 3 months before, or 3+ steady outdoor runs with heart rate (and running power, for the power markers). Missing markers are left out, not counted as zero, and the prediction uses the rest.
Why are there no power markers for my older races?
Apple Watch running power needs a Series 6 or later with watchOS 9 or newer. Races from before you had one simply use VO2max and distance per heartbeat.
What counts as a "steady run"?
An outdoor run of 5 km (3.1 miles) or more at an easy to moderate effort: an average heart rate between about 67% and 86% of your maximum. Treadmill runs, short jogs and hard sessions are left out, so runs compare fairly with each other. At least 3 are needed in each window.
Health data
My runs are saved by Strava, Runna or another app. Does that work?
Yes. If your Watch was recording heart rate and power during the run, Splitcast uses those samples whichever app saved the workout. Runs saved by more than one app are counted once.
The app was slow to respond right after I allowed Health access
Health can take a few seconds to answer the first requests after you grant access, especially with years of data. It only happens on the first read.
How do I refresh or re-read my data?
Splitcast keeps a copy of your Health data so it opens quickly. In Results, tap Refresh for a quick update, or "Re-read all history" after fixing old workouts in Health. The app reminds you if the copy is more than 30 days old.
How do I change what Splitcast can read?
In the Settings app: Health › Data Access & Devices › Splitcast. Splitcast never writes to Health.
Widgets and alerts
How do I add a widget?
Touch and hold the Home Screen or Lock Screen, tap Edit › Add Widget and choose Splitcast. Touch and hold the widget and choose Edit Widget to pick a distance, or let it follow your goal.
My widget says the data is old
Widgets update when Splitcast is woken after a workout is saved, if "Update in the background" is on in Results › Settings. iOS can't read Health while your phone is locked, so it catches up next time. Opening the app always refreshes them.
What are goal alerts?
Optional notifications when your prediction moves within 10%, 5% or 2% of your goal, or beats it. At most one a day, never for getting less fit. Turn them on in Results › Settings.
Contact
Found a bug or have an idea? Email [contact email]. Screenshots help a lot.