Permanent standard time
EARLIER LIGHTThe winter clock, all year long.
Sunrise
Sunset
01/Explore a day
Explore the options
for your day.
Pick a place and a date. Then move through the day to see the same clock time under both choices.
JANDEC
Permanent daylight saving
LATER LIGHTThe summer clock, all year long.
Sunrise
Sunset
The full 24 hours
DarkTwilightDaylight
StandardDaylight
12 AM6 AM12 PM6 PM12 AM
White markers: your morning departure and evening free-time start. Twilight is some light with the sun below the horizon.
Customize to your daily schedule.
These times update the whole explorer.
We count sunlight inside these two windows, assuming the same schedule every day. Sunrise to sunset counts as daylight; twilight is shown but excluded from the totals.
02/See your year
A winter morning is the real test.
Summer evenings make the case for daylight saving. Winter mornings are the real pain point. Compare sunrise and sunset through the year to see how both fit your schedule.
Permanent standardPermanent daylight savingCurrent schedule
Point at the chart to inspect a date. Click or tap to use it above. The date slider also moves the chart marker.
With permanent standard time
With permanent daylight saving
| 2026 snapshot | Standard sunrise | Daylight sunrise | Standard sunset | Daylight sunset |
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03/The tradeoffs
There’s a good reason for each.
Your lifestyle preference and the public-health evidence can point in different directions. Both are useful considerations.
The case for standard time.
Protect the morning. Let evening arrive earlier.
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Earlier light for early starts
Sunrise arrives an hour earlier than under daylight saving. Depending on your location and schedule, that can put sunlight into the school run, commute, or morning walk. This is a direct consequence of the clock shift.
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The stronger case from sleep science
The American Academy of Sleep Medicine recommends permanent standard time because it better aligns with circadian biology. Morning light helps set the body clock; later evening light can shift it later. [1]
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Earlier sunsets, all year
Compared with daylight saving, you lose an hour at the evening end. In winter, the sun may already be down when work ends. Summer sunsets also arrive an hour earlier than the familiar summer clock.
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Some summer light arrives while you sleep
In northern or eastern parts of a time zone, sunrise can be very early. If you sleep through that extra morning hour, it may feel less useful than light after work. Check your own windows above.
The case for daylight saving.
Keep the evening. Accept a later morning.
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Later light after work
Sunset arrives an hour later on the clock. With a fixed workday, that can mean more sunlit time for exercise, play, errands, or dinner outside. The gain depends on when your free time starts and ends.
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Keep the familiar summer evenings
Where seasonal daylight saving is observed, permanent daylight saving preserves summer sunrise and sunset clock times. It also avoids the autumn clock change that makes sunset suddenly appear an hour earlier.
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Winter mornings get darker
The one-hour delay applies in December and January, too. Sunrise can move beyond the start of work or school, especially far north or near the western edge of a time zone. The city selector makes that difference visible.
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Later light has a biological cost
More evening light and less morning light can push sleep timing later, while work and school still start at the same clock time. Sleep organizations favor standard time; individual schedules and actual light exposure vary. [2]
Energy savings are a separate, uncertain argument. A US Department of Energy study found a small electricity saving from extending seasonal daylight saving by four weeks in 2007. That result is not a measurement of permanent daylight saving. [3]
04/Your decision
Which hour of daylight
matters more to you?
Choose the light that matters more in your life. We’ll compare sunlight in your available time across the whole year.
How the comparison works ↓A brief history of time zones and daylight saving
Railroads adopt time zones
U.S. and Canadian railroads coordinate four time zones, replacing a patchwork of local solar times.
The first federal daylight saving law
The Standard Time Act establishes federal time zones and seasonal daylight saving during World War I.
Daylight saving is repealed
Congress overrides President Wilson’s veto. Federal daylight saving ends; some communities keep it locally.
“War Time” brings it back
Year-round daylight saving returns during World War II, ending in September 1945. Local differences then return.
A uniform seasonal schedule
The Uniform Time Act sets nationwide change dates while allowing states to stay on standard time.
A year-round experiment
An energy-crisis trial starts in January 1974. Congress restores standard time that October for four months; seasonal switching resumes in 1975.
An earlier spring change
A 1986 law moves the start of daylight saving to the first Sunday in April.
The season gets longer
A 2005 law takes effect: daylight saving runs from the second Sunday in March to the first Sunday in November.
The Senate backs permanent daylight saving
The Sunshine Protection Act passes the Senate but does not become law.
The debate continues
The House passes another Sunshine Protection Act proposal. Congress also considers proposals for permanent standard time.
Timeline sources: U.S. Department of Transportation and Congressional Research Service (July 2026 report).
The assumptions behind the sunlight
All dates are in 2026. Sunrise, sunset, and civil twilight are calculated in your browser with SunCalc 1.9.0 using each location’s latitude and longitude and a level, unobstructed horizon. Times are approximate and rounded to the nearest minute. Terrain, altitude, clouds, and atmospheric conditions affect the light you experience. The landscape is an illustration: its sky colors blend gradually around dawn and dusk, while the labels follow the exact sunrise, sunset, and civil-twilight cutoffs. The colors do not represent weather.
“Standard” uses the selected location’s fixed standard UTC offset. “Daylight saving” uses that offset plus one hour on every date. Both are hypothetical permanent clocks.
The optional seasonal line models the US March–November rule: daylight saving from the second Sunday in March through the day before the first Sunday in November. It is a comparison schedule, not a prediction about legislation. Arizona and Hawaii cities in this list omit seasonal changes. The 2026 change dates are March 8 and November 1.
“Without sunlight at departure” counts days when the sun is below the horizon at departure, including twilight. “Sunlight left at free-time start” counts days when the sun is up at that time. These are daylight opportunities; they do not measure your actual outdoor exposure.
How your preference is calculated
For every day, we calculate the minutes between sunrise and sunset that overlap your morning window and your evening window. We add those minutes across all 365 days. Your routine stays at the same clock times under both options, including weekends. Twilight is excluded.
The switch picks the window that matters more to you. We compare the annual sunlit hours in that window under each clock, and show what the winning clock does to your other window. The result only describes this sunlight preference; it does not combine sleep outcomes, economics, safety, weather, or personal health. Your selected date affects the day preview, while this comparison always uses the full year.
Your settings are saved in this browser when local storage is available. “Share this view” creates a link containing the location, date, routine, and preferences. The explorer does not request your device location. Google Analytics measures visits and engagement; shared-link query strings and fragments are excluded from the page and referrer URLs reported to Analytics, and your routine settings are not sent as events.
Sources and further reading
GeoNames: city coordinatesCity centers from the GeoNames geographical database, CC BY 4.0.
[1] AASM: permanent standard time positionUpdated position announced in 2023; published in January 2024.
[2] AASM: clock changes and circadian biology2020 position statement; separates transition risks from chronic effects.
[3] US Department of Energy: energy study2008 report about four additional weeks of seasonal daylight saving.
[4] SunCalc: astronomical calculationsOpen-source sunrise, sunset, and civil-twilight calculations; MIT license.
[5] NOAA: why observed sun times varyBackground on horizons, atmospheric refraction, and approximate solar times.