How accurate are the times?

Within about one minute at latitudes between 60° N and 60° S. Near the poles the sun can stay up or down for weeks, so the tool reports "polar day" or "polar night" instead of a time.

The period when the sun is between roughly 6° below and 6° above the horizon, producing the warm low-angle light favored by photographers. The tool also reports blue hour (sun 4–8° below the horizon).

Does it account for elevation and atmospheric refraction?

It uses the standard refraction correction (34 arcminutes) at sea level. For high elevations or unusual atmospheric conditions the times can shift by a minute or two.

Is my location sent anywhere?

No. Coordinates and the solar calculation stay in your browser.

NOAA algorithm · golden / blue hour · live

Sunrise, sunset & golden hour for any place

Pick latitude, longitude and a date. We compute sunrise, sunset, solar noon, civil/nautical/astronomical twilight using the NOAA solar algorithm. Accurate to ±1 minute.

Quick Start

How solar times are computed

The NOAA algorithm derives solar declination and equation of time from Julian centuries since J2000, then projects sun events for your latitude and longitude.

01
Enter location
WGS-84 lat/lng. Decimal degrees. Negative south/west.
Parsing accepts ISO 8601, RFC 3339, RFC 2822, and Unix epoch seconds/milliseconds. The Date constructor handles the rest with browser-engine consistency.
locISO 8601RFC 3339epochlive
lat,lng · timestampWGS-84 · ISO
```
40.71, -74.01
```
loaded · ISO 8601zone · ready
02
Pick a date
Any calendar date. The algorithm handles polar days.
All math runs in UTC internally to avoid DST landmines; presentation converts back to the user’s zone via Intl.DateTimeFormat.
dateUTC mathIntlDST-safelive
date · optionsinput · live
```
2026-05-21
```
options applied · UTCDST-safe
03
Solar geometry
Declination + equation-of-time → solar noon and hour angle.
Output respects the chosen timezone offset (Z vs +05:30) and pads digits per ISO conventions so sorts stay chronological.
sunoffsetzone-awaresortablepadded
noon · computed12:55 · ready
```
hour angle = …
```
computed · instantsortable
04
Read events
Sunrise, sunset, golden hour (civil twilight) and astronomical twilight all derived from zenith angles.
Copy writes via the Async Clipboard API; nothing pings a time server — the browser’s clock is the only oracle.
eventsclipboardno oracledeterministicclient-side
✓ · copiedready · done
```
05:39 → 20:18
```
shipped · ready to shipsuccess

Pro tips

Time math without DST landmines

Always store UTC

Convert to local for display only. UTC storage avoids DST jumps and timezone drift in databases.

Watch leap seconds

POSIX time doesn’t count leap seconds; some systems do. Don’t use timestamps for sub-second precision across boundaries.

Prefer Temporal eventually

The Date API has many quirks. Temporal is shipping in modern engines and handles zones correctly.

Cron is timezone-tricky

Cron expressions run in the daemon’s local zone unless told otherwise. Pin a TZ explicitly for predictable runs.

ISO 8601 sorts naturally

YYYY-MM-DDTHH:mm:ss sorts correctly as a string. Don’t use US-style MM/DD/YYYY for anything machine-readable.

Beware Y2K38

Signed 32-bit Unix timestamps overflow in 2038. Use 64-bit storage end-to-end for long-lived systems.

Use Cases

When to query sun times

Photography, agriculture, travel.

Photography

Plan a shoot during golden hour. Math runs in UTC under the hood to dodge DST jumps — local time is only for display. That means scheduling logic and date diffs survive March / November fall-back without the classic off-by-one-hour bug.

DST-safe

Astronomy

Astronomical twilight tells you when the sky goes dark. Browser clock is the only source — no external time server, no privacy leak, no rate limit. Pair with NTP-synced server time for high-accuracy use cases, but for human-scale work the browser clock is plenty.

UTC-correct

Agriculture

Match field work with daylight. ISO 8601 output sorts naturally as strings, perfect for filenames (report-2026-01-15.pdf) and log lines that need chronological ordering without parsing. Drop into S3 keys for free time-bucketing.

ISO-sortable

Smart home

Trigger lights at civil twilight. Pairs cleanly with cron, scheduled tasks, and timestamped log analysis. The tool's output drops directly into APScheduler, Linux cron, or GitHub Actions schedule expressions without re-formatting.

spec-grade

Travel

Plan hikes to finish before dark. Output respects the chosen timezone offset (Z vs +05:30) so REST APIs and database TIMESTAMP WITH TIME ZONE columns round-trip cleanly. No ambiguity between "noon UTC" and "noon local".

zone-aware

Religious obs.

Know prayer / fast windows. Confirms the difference between epoch seconds (10 digits) and milliseconds (13 digits) before you commit code that mis-multiplies by 1000 — a classic bug in cross-language time handling.

epoch-accurate

FAQ

Frequently asked questions

How accurate is it?

Within ±1 minute for most latitudes. Polar regions degrade due to the algorithm's approximations.

Civil vs nautical vs astronomical?

Civil: sun 6° below horizon (lights useful). Nautical: 12° (horizon visible). Astronomical: 18° (stars fully visible).

What timezone are times in?

Your browser timezone — change OS TZ to see another place.

Why does the sun never set?

Polar day — happens in summer above ~66.5° latitude.

Is anything sent to a server?

No. The whole NOAA calc runs in your browser.

Suggest a tool

Something missing?

Tell us what you need. We ship the top requests every two weeks.

47 in queue·8 shipped this month

Request queued. Thanks!