# Daylight duration calculator

> Daylight hours vary dramatically with latitude and season. Enter your latitude to get monthly daylight averages for a full year, or a day-by-day breakdown for any date range, plus.

Calculate daylight hours for any latitude across a full year or a custom date range. See monthly averages, the longest and shortest days, and solstice and equinox dates.

**Interactive version:** https://onlinecalculator.me/date-time/daylight-duration/
**Category:** Date & Time

## How daylight varies by latitude

| Latitude | Summer solstice | Winter solstice | Equinox |
|----------|----------------|----------------|---------|
| 0° (equator) | ~12h | ~12h | ~12h |
| 23.5° (tropics) | ~13.5h | ~10.5h | ~12h |
| 40° (mid-latitudes) | ~15h | ~9.5h | ~12h |
| 66.5° (Arctic Circle) | ~24h (polar day) | ~0h (polar night) | ~12h |
| 90° (North Pole) | ~24h (6 months) | ~0h (6 months) | ~12h |

## Solstices and equinoxes

The calculator finds these automatically by scanning each day of the year:

- **Summer solstice** (N. hemisphere) — the day with the most daylight, around June 21
- **Winter solstice** (N. hemisphere) — the day with the least daylight, around December 21
- **Spring and fall equinoxes** — the days when daylight is closest to 12 hours, around March 20 and September 22

For the southern hemisphere, summer and winter are swapped.

## Worked example

**Latitude 40° N, 2026 — June (summer)**

Average June daylight: approximately 14.8h. Longest day (June 21): approximately 15.0h. Shortest day in June (June 1 or 30): approximately 14.6h.

## Notes

- Monthly averages are rounded to one decimal place.
- Date range mode is capped at 366 rows for browser performance.
- All times are UTC-meridian (longitude 0) calculations; local clock time depends on your time zone.

## Frequently asked questions

### How is daylight duration calculated?

The calculator uses the NOAA solar algorithm to find sunrise and sunset times at the given latitude (with longitude fixed at 0 for UTC). The difference between sunset and sunrise minutes gives the daylight duration for each day.

### Why is longitude fixed at 0?

Longitude shifts the clock time of sunrise and sunset but does not change the total duration of daylight for a given latitude and date. Fixing longitude at 0 gives accurate daylight durations regardless of where you are in a time zone.

### What are polar day and night?

Above the Arctic Circle (about 66.5° N) or below the Antarctic Circle (66.5° S), the sun may remain above the horizon for an entire 24-hour period (polar day) or below the horizon all day (polar night) near the solstices. The calculator reports 24h or 0h for these conditions.

### How accurate are the solstice and equinox dates?

The dates are approximate, found by scanning each day of the year for the maximum, minimum, and ~12-hour daylight points. They are accurate to within 1–2 days for practical purposes.

### Does daylight saving time affect the results?

No. The calculator reports raw solar daylight duration, which is independent of clock time and daylight saving time adjustments.

### How do I use the date range mode?

Switch to "Date range," enter a start and end date, and the calculator shows a day-by-day table of daylight hours, sunrise, and sunset times for the chosen latitude.

## Sources

- [Sunrise equation](https://en.wikipedia.org/wiki/Sunrise_equation) — Wikipedia
- [NOAA Solar Calculator](https://gml.noaa.gov/grad/solcalc/) — NOAA Global Monitoring Laboratory
- [Daytime (length of day)](https://en.wikipedia.org/wiki/Daytime) — Wikipedia

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