Methodology

1. The day of the triggering event is excluded.
2. Calendar-day periods count every intervening day; court-day periods skip weekends and court holidays, and each skipped day is named in the audit trail.
3. The counted period is brought to a court day before any service extension is added — the Fed. R. Civ. P. 6(a)(1)(C) then 6(d) sequence.
4. The service extension for the selected method is applied, in calendar days or court days depending on what the rule provides. Cal. Code Civ. Proc. § 1013(a) mail extensions are calendar days; § 1013(c) and § 1010.6(a)(4) extensions are court days.
5. If the resulting date is still a weekend or holiday, it rolls to the next valid court day in the direction the rule specifies.

Federal holidays close every court modeled here. California judicial holidays that are not federal holidays — Lincoln's Birthday and Cesar Chavez Day — close California courts only, and are never applied to a federal calculation.

Dates are treated as timezone-free calendar dates. No UTC conversion is performed, so a deadline never shifts based on the device's location or clock.

58 deadline periods are modeled: the Federal Rules of Civil, Appellate, Criminal, and Bankruptcy Procedure, and the California Code of Civil Procedure and Rules of Court. Holiday data runs from 2020 to 2040, and a calculation that would fall outside that range is refused rather than guessed.

Not modeled: county and courtroom-specific closures, judge-specific standing orders, emergency closures, tolling agreements, and any deadline set by a case-specific scheduling order. Where a rule has interacting clocks — the two Rule 15(a)(1) periods, for instance — the calculator computes one and the rule page tells you to compare.

Each rule page states whether its encoding has been checked against the official text and links to that text. Where no check is recorded, the page says so plainly.

CourtDayCalculator is a reference tool, not legal advice, and using it creates no attorney–client relationship. You remain responsible for confirming every deadline against the governing rule and your court's requirements.