CalculationTime

Day Length Calendar

Date+ location+ altitude -0.833 deg= sunrise
KnownDate + placeFindSunriseAltitude-0.833 degAzimuthTrue bearingSkyPre-dawnLimitLevel horizon
CalculationTime

Day Length Calendar

Calculate daylight length for a calendar date by subtracting Astronomy Engine sunrise from sunset for the entered observer location.

Inputs, result, proof and time.

Use the instrument above, then check the calculation record, assumptions and related tools below.

Working Calendar

Day Length Calendar calculator

This calendar route reuses the live calculator from Day Length Calculator, then keeps the formula, assumptions and source boundary visible on the calendar URL.

Sun/Moon/Astronomy

Day Length Calculator

Live answer9h 54m daylightAstronomy Engine SearchRiseSet(Sun) found sunrise 2026-06-20 21:00 UTC / 2026-06-21 07:00 (UTC+10) and sunset 2026-06-21 06:53 UTC / 2026-06-21 16:53 (UTC+10) for -33.9°, 151.2°.
Live result9h 54m daylightAstronomy Engine SearchRiseSet(Sun) found sunrise 2026-06-20 21:00 UTC / 2026-06-21 07:00 (UTC+10) and sunset 2026-06-21 06:53 UTC / 2026-06-21 16:53 (UTC+10) for -33.9°, 151.2°.
Formula used

observer = Astronomy.Observer(latitude, longitude, elevationMetres). t0 = local civil midnight converted to UTC. Sunrise = SearchRiseSet(Sun, observer, +1, t0, 1.05). Sunset = SearchRiseSet(Sun, observer, -1, t0, 1.05). Daylight length = sunset - sunrise.

This is the method behind the answer, so the result can be checked rather than simply trusted.

Live math canvas

Your numbers, formula and explanation together

Day Length Calculator: 9h 54m daylight. Astronomy Engine SearchRiseSet(Sun) found sunrise 2026-06-20 21:00 UTC / 2026-06-21 07:00 (UTC+10) and sunset 2026-06-21 06:53 UTC / 2026-06-21 16:53 (UTC+10) for -33.9°, 151.2°.

Formula applied

The exact method behind this answer

CalculationTime keeps the method visible so the number can be checked instead of blindly trusted.

observer = Astronomy.Observer(latitude, longitude, elevationMetres). t0 = local civil midnight converted to UTC. Sunrise = SearchRiseSet(Sun, observer, +1, t0, 1.05). Sunset = SearchRiseSet(Sun, observer, -1, t0, 1.05). Daylight length = sunset - sunrise.
  1. Apply the formulaobserver = Astronomy.Observer(latitude, longitude, elevationMetres). t0 = local civil midnight converted to UTC. Sunrise = SearchRiseSet(Sun, observer, +1, t0, 1.05). Sunset = SearchRiseSet(Sun, observer, -1, t0, 1.05). Daylight length = sunset - sunrise.9h 54m daylightAstronomy Engine SearchRiseSet(Sun) found sunrise 2026-06-20 21:00 UTC / 2026-06-21 07:00 (UTC+10) and sunset 2026-06-21 06:53 UTC / 2026-06-21 16:53 (UTC+10) for -33.9°, 151.2°.

Your live breakdown

Current inputs in the calculation

These values come from the controls above and update when the calculator changes.

Year
2,026
Month
6
Day
21
Latitude
-33.9 degrees
Use positive for north, negative for south.
Longitude
151.2 degrees
UTC offset
10 hours
Elevation
0 metres

Resulting answer

9h 54m daylight

Astronomy Engine SearchRiseSet(Sun) found sunrise 2026-06-20 21:00 UTC / 2026-06-21 07:00 (UTC+10) and sunset 2026-06-21 06:53 UTC / 2026-06-21 16:53 (UTC+10) for -33.9°, 151.2°.

Answer
9h 54m daylight
Live support
Astronomy Engine SearchRiseSet(Sun) found sunrise 2026-06-20 21:00 UTC / 2026-06-21 07:00 (UTC+10) and sunset 2026-06-21 06:53 UTC / 2026-06-21 16:53 (UTC+10) for -33.9°, 151.2°.

Assumptions used

What this answer assumes

Astronomy Engine sunrise/sunset difference with manual UTC-offset display. Official local sunrise/sunset services may differ because horizon and legal definitions vary.

  • Astronomy Engine computes sunrise and sunset for the entered observer location.
  • Timezone offset is entered manually and does not apply daylight-saving rules automatically.
  • Flat horizon and entered elevation are used; local terrain and buildings can change visible daylight.
  • Polar day/night edge cases are reported when no same-day sunrise/sunset pair is found.

Master’s Tip

How to use the result well

Master’s Tip: daylight length is only as local as the observer data. Check latitude, longitude, elevation and UTC offset before comparing places.

Printable record

What belongs in the saved calculation

Save the inputs, result, formula, assumptions, page URL and date together so the calculation can be reviewed later.

Year
2,026
Month
6
Day
21
Latitude
-33.9 degrees
Use positive for north, negative for south.

Visual grid

This number is one point on a larger pattern

Day Length is not just a final answer. It is a step on a line: before and after, input and output, assumption and result.

Micro-timehours, minutes, shiftsHuman scaledays, weeks, projectsMacro-timemonths, years, calendars
InputFormulaResult
9h 54m daylight

CalculationTime keeps the path visible: the input, the method and the final number belong together.

CalculationTime

Day Length Calculation Report

Report date:

9h 54m daylightAstronomy Engine SearchRiseSet(Sun) found sunrise 2026-06-20 21:00 UTC / 2026-06-21 07:00 (UTC+10) and sunset 2026-06-21 06:53 UTC / 2026-06-21 16:53 (UTC+10) for -33.9°, 151.2°.

Inputs

Year
2,026
Month
6
Day
21
Latitude
-33.9 degrees
Longitude
151.2 degrees
UTC offset
10 hours
Elevation
0 metres

Method

observer = Astronomy.Observer(latitude, longitude, elevationMetres). t0 = local civil midnight converted to UTC. Sunrise = SearchRiseSet(Sun, observer, +1, t0, 1.05). Sunset = SearchRiseSet(Sun, observer, -1, t0, 1.05). Daylight length = sunset - sunrise.

  1. At latitude -33.9°, longitude 151.2° and UTC+10 on 21 June 2026, the calculator searches for that local day's sunrise and sunset, then subtracts the two instants.

Assumptions

  • Astronomy Engine computes sunrise and sunset for the entered observer location.
  • Timezone offset is entered manually and does not apply daylight-saving rules automatically.
  • Flat horizon and entered elevation are used; local terrain and buildings can change visible daylight.
  • Polar day/night edge cases are reported when no same-day sunrise/sunset pair is found.

Notes

Use this space on the printed report for client, supplier, classroom, job-location, measurement, quote or approval notes.

Source: https://www.calculationtime.com/calculators/day-length-calculator

This report shows the calculation inputs, formula, assumptions and result for review. It is not legal, payroll, tax, engineering, financial or academic advice unless a qualified professional confirms the applicable rules.

Method

The calendar turns sunrise and sunset into a daylight span

The route finds the Sun rise and set instants for the selected location/date using Astronomy Engine SearchRiseSet, then subtracts sunrise from sunset to produce the daylight duration.

Formula

observer = Astronomy.Observer(latitude, longitude, elevationMetres). t0 = local civil midnight converted to UTC. Sunrise = SearchRiseSet(Sun, observer, +1, t0, 1.05). Sunset = SearchRiseSet(Sun, observer, -1, t0, 1.05). Daylight length = sunset - sunrise.

Assumptions

Astronomy Engine computes sunrise and sunset for the entered observer location. Timezone offset is entered manually and does not apply daylight-saving rules automatically. Flat horizon and entered elevation are used; local terrain and buildings can change visible daylight. Polar day/night edge cases are reported when no same-day sunrise/sunset pair is found.

Trust boundary

Day length depends on location, elevation, horizon and civil-time assumptions. Polar edge cases and official schedules need specialist local almanac data.

Source Notes

Day Length Calendar keeps the source limits visible

CalculationTime calculates day length by subtracting Astronomy Engine sunrise and sunset instants for the entered observer location.

ReferencesAstronomy Engine - rise and set searchNOAA Solar Calculation DetailsTime and Date - Sunrise and Sunset explanation