Calculate Daylight Savings Time Dates

DST Start Date Formula:

\[ \text{Start Date} = \text{March 1} + (14 - \text{Weekday(March 1)} + 7 \text{ If Needed}) \]

Calculates DST start as second Sunday in March.

DST Start Date:

DST End Date:

Definition: DST is the practice of setting clocks forward by one hour during warmer months to extend evening daylight.

Purpose: Designed to make better use of daylight and conserve energy, though effectiveness varies by region.

The calculator uses standard US DST rules:

\[ \text{Start Date} = \text{Second Sunday in March} \] \[ \text{End Date} = \text{First Sunday in November} \]

Calculation Method:

Details: Knowing exact DST dates helps with scheduling, time-sensitive systems, and avoiding confusion in time-sensitive operations.

Tips: Simply enter any year between 2000-2100 to calculate DST transition dates for that year.

Q1: Are these dates valid worldwide?
A: No, this calculator uses US DST rules. Other countries have different DST schedules.

Q2: When do clocks change?
A: In the US, clocks spring forward at 2am (to 3am) on start date, and fall back at 2am (to 1am) on end date.

Q3: Have DST dates always been the same?
A: No, US DST rules changed in 2007. This calculator uses current rules (2007 onward).

Q4: Do all states observe DST?
A: Most do, but Arizona (except Navajo Nation) and Hawaii don't observe DST.

Q5: Will these dates ever change?
A: Possibly. Congress can change DST rules, as happened with the Energy Policy Act of 2005.