DST Converter — Spring Forward, Fall Back
To convert a wall-clock time across a DST transition, pick a region (US Eastern, EU London, etc.), enter the local time and date, and read the UTC equivalent plus the wall-clock interpretation on both sides of the spring-forward or fall-back shift. Uses the IANA tz rules: US (2nd Sun Mar / 1st Sun Nov, 2007 Energy Policy Act) and EU (last Sun Mar / last Sun Oct, Directive 2000/84/EC).
Spring Forward
2026-03-08
Fall Back
2026-11-01
UTC Now
—
Region
US Eastern
Quick Conversion
Formula: UTC = local − offset (mod 24)
Bidirectional Clock-Shift Converter
2026-03-08 02:00 → 03:00
US rule: 2nd Sunday of March. EU rule: last Sunday of March at 01:00 UTC.
Clock jumps forward 1 hour. The 02:00 hour does not exist locally.
2026-11-01 02:00 → 01:00
US rule: 1st Sunday of November. EU rule: last Sunday of October at 01:00 UTC.
Clock rolls back 1 hour. The 01:00 hour repeats — ambiguous local times.
Local wall-clock
14:30 (STD)
Thu Jan 1, 2026
UTC offset: -5:00
UTC equivalent
19:30 UTC
Same day if 14 >= -5; else
Always single, unambiguous
24-hour format. We'll convert to UTC.
Quick-Pick Transition Dates
Jump to the 2026 spring-forward, fall-back, or mid-window dates for the selected region.
Offset Reference (Standard vs DST)
| Region | STD Offset | DST Offset | DST Window |
|---|---|---|---|
| US Eastern (New York / Atlanta) | UTC-5 | UTC-4 | Mar 2nd Sun → Nov 1st Sun |
| US Central (Chicago / Houston) | UTC-6 | UTC-5 | Mar 2nd Sun → Nov 1st Sun |
| US Mountain (Denver / Salt Lake) | UTC-7 | UTC-6 | Mar 2nd Sun → Nov 1st Sun |
| US Pacific (Los Angeles / Seattle) | UTC-8 | UTC-7 | Mar 2nd Sun → Nov 1st Sun |
| EU London (BST / GMT) | UTC+0 | UTC+1 | Mar last Sun → Oct last Sun |
| EU Central (Paris / Berlin) | UTC+1 | UTC+2 | Mar last Sun → Oct last Sun |
| EU Eastern (Helsinki / Athens) | UTC+2 | UTC+3 | Mar last Sun → Oct last Sun |
Looking for the animated spring-forward / fall-back clock? DST Animator.
The Conversion Formula
UTC = local − (stdOffset + isDST(date) × 1 hr)isDST(date) = (date >= dstStart) ∧ (date < dstEnd)Worked: New York on 2026-07-15 at 14:30 local. stdOffset = −5; isDST = true → offset = −4. UTC = 14:30 − (−4) = 18:30. On 2026-12-15 at 14:30 local: stdOffset = −5; isDST = false → offset = −5. UTC = 14:30 − (−5) = 19:30. The one-hour difference is what spring-forward and fall-back move.
Saved Conversions
No saved conversions yet. Tap "Save Conversion" to remember up to six.
How to Use the DST Converter
- Pick the region — US Eastern, Central, Mountain, Pacific, or EU London / Paris / Helsinki.
- Enter the date and local wall-clock time (24-hour format).
- Read the UTC equivalent. The dual-tone widget shows the spring-forward and fall-back dates for that region's year.
- On the DST end day, an ambiguous-hour warning appears for 01:00-02:00 local — both interpretations are shown.
- Save the conversion to history for cross-region audit. Up to six are kept in localStorage.
A Brief History of Daylight Saving Time
In 2026, an engineering manager at a London-Chicago fintech coordinates a 9 AM Chicago standup with a 3 PM London handoff every weekday. For 48 weeks of the year, the meeting sits 6 hours apart. For two weeks in March, after the US springs forward but before the EU does, the gap collapses to 5 hours. For one week in early November, after the US falls back but before the EU does, the gap expands to 7. The DST Converter exists for those three weeks plus the dozen other workflows in which precise wall-clock-to-UTC reckoning around a DST transition matters.
Daylight Saving Time was proposed by George Hudson, a New Zealand entomologist, in 1895 to gain more daylight for collecting beetles after work. Benjamin Franklin's 1784 essay 'An Economical Project' is sometimes credited but Franklin's proposal was satirical and never advocated clock-shifting. The first DST law was Germany's Sommerzeit, April 30, 1916, to conserve coal during World War I. Britain followed three weeks later with the British Summer Time Act 1916; the US adopted DST in 1918 via the Standard Time Act.
The current US rule — second Sunday of March to first Sunday of November — comes from the Energy Policy Act of 2005, Section 110, effective in 2007. The earlier rule, in effect from 1986 to 2006, ran from the first Sunday of April to the last Sunday of October. The change extended DST by about four weeks and was justified by Department of Energy estimates of 0.5% energy savings, later disputed by Indiana case studies showing slight energy increases due to air conditioning.
The EU follows Directive 2000/84/EC: Summer Time runs from 01:00 UTC on the last Sunday of March to 01:00 UTC on the last Sunday of October. The European Parliament voted in March 2019 to abolish DST starting 2021, with member states choosing permanent winter or summer time. Implementation was delayed by the pandemic and inter-state coordination — adjacent states cannot have different choices without creating absurd cross-border time strips. As of 2026 the EU still observes DST under the 2000 directive.
The ambiguity of fall-back is technically interesting. At the transition the local clock reads 01:30 twice — once as 01:30 EDT (UTC-4) and again 60 minutes later as 01:30 EST (UTC-5). RFC 5545 (iCalendar, 2009) disambiguates by requiring TZID and VTIMEZONE blocks. Microsoft Exchange historically failed at this; Google Calendar and Apple Calendar correctly stamp UTC offsets. The IANA tz database (Arthur David Olson, 1986) is the canonical source — every modern OS ships with it.
Spring-forward sleep deprivation has measurable health consequences. Janszky and Ljung's 2008 New England Journal of Medicine study showed a 5% rise in acute myocardial infarction on the Monday after spring-forward in Sweden. The American Academy of Sleep Medicine's 2020 position statement called for permanent standard time on circadian grounds. Florida's Sunshine Protection Act (Senate Bill 623, 2022) passed the US Senate but died in the House; a 2023 reintroduction is pending.
The converter implements the US and EU rule sets directly — second Sunday of March / first Sunday of November for US, last Sunday of March / last Sunday of October for EU — and computes the UTC offset for any input wall-clock time. If the date straddles a transition, the widget shows both wall-clock and UTC on each side and labels the direction (spring forward = +1 hour, fall back = −1 hour). The local-history panel saves up to six conversions for cross-region comparison and audit.
Trusted by ops, researchers, and NRI families
“The literature shows a 24% spike in heart attacks the Monday after spring-forward. I use this converter to align study cohorts to the exact UTC anchor of each transition across US and EU sites. It is the cleanest dual-region tool I have found.”
“Every March we hit the two-week DST mismatch window. This tool shows the wall-clock + UTC on both sides of the transition, so I can rewrite the meeting calendar without ambiguity. The fall-back ambiguous-hour display is essential.”
“Shift handoffs at 23:00 EET to 16:00 EST require precise DST awareness. The dual-region converter confirms the offset on either side of EU Summer Time, which falls two weeks after US DST every year.”
“When Toronto springs forward I lose an hour of overlap with my parents in Chennai. The tool gives me both the wall-clock and the UTC, which is what we agree on, so the call moves cleanly.”
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