Home › Methodology

How we build this

Every date on this site is either something we read from a district's own calendar, or an estimate we've clearly labeled as one. Here's exactly how that works.

Where the dates come from

We collect board-adopted calendars, district PDFs, and school-portal pages — the districts' own sources. We extract the dates (first day, last day, holidays, breaks, half days), then reconcile each district against its federal NCES identifier so the record joins cleanly to Census and enrollment data. For confirmed districts we keep the URL we read it from.

Observed vs estimated — and how you can tell

The single most important thing on any page is whether a date is confirmed or a guess. We never hide that in metadata.

✓ Observed

Read directly from the district's published calendar. Shown solid, "printed."

◩ Estimated

Not yet confirmed — estimated from nearby districts or past years. Shown hatched and labeled with the word "estimated."

The treatment is designed to survive greyscale and a screenshot in a group chat — texture and an explicit word, never color alone. Weekends and fixed holidays stay solid even in an estimated district, because a Saturday isn't a guess.

How we estimate the rest

When we haven't found a district's calendar for a given year, we don't leave the page blank — but we don't pretend, either. We estimate its dates from the patterns of nearby districts in the same state and from that district's own history in prior years, and we mark every estimated date. Estimates carry honest, low confidence; a state-pattern guess sits far below a confirmed date.

Confidence, per date

Every date carries a confidence score derived from how directly we observed it and whether it was corroborated — never a number we simply asserted. Businesses reading the API get that score on every row and can filter to a threshold. Families don't see a number; they see the plain label instead, because "0.12" means nothing to a person.

Honest coverage, by school year

The current year is the weak one — collection is live right now and improving daily. Older years are strong. We publish the real figures:

School yearDistrictsConfirmed
2026–27 (current)12,02339.9%
2025–2613,63684%
2024–2511,62176%

Confirmed = read from the district's own calendar. Everything else is estimated and labeled.

How often it updates

Calendars change — a snow day here, a board revision there. We re-check sources daily and version the changes, so what you read is current and the archive keeps its history.

The one thing we always ask

For anything that matters — a flight, childcare, a day off work — confirm with your district's official calendar. We're an independent record, not the school. If you spot something wrong, the "this doesn't look right" button on any district page goes straight to us.