# How are UK prayer times calculated? | UK Prayer Times

> This site defaults to London Unified for London, Watford, Slough and Woking. Other listed cities default to Muslim World League (Fajr 18°, Isha 17°)…

*Source: https://prayer-times.co.uk/answers/how-are-uk-prayer-times-calculated · Page updated: 2026-07-17 · Independent, free UK prayer times.*

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Methodology

# How are UK prayer times calculated?

Updated 2026-09-08

Quick Answer

This site defaults to London Unified for London, Watford, Slough and Woking. Other listed cities default to Muslim World League (Fajr 18°, Isha 17°) computed locally from city coordinates. Times are baked into HTML daily and verified by automated checks.

## In detail

No third-party prayer-time API is used. Outside London, the adhan astronomical library computes times from latitude, longitude and date, with British Summer Time handled automatically.

At northern latitudes (Aberdeen, Inverness, Glasgow, Edinburgh and others) the sun may not reach 18° below the horizon in summer. When that happens, Fajr and Isha use a documented one-seventh-of-the-night adjustment, disclosed on the city page.

Asr can be viewed as Standard (shadow = length) or Hanafi (shadow = 2× length).

This answer is not

A substitute for the board at the mosque you will pray in. Start times and iqamah differ. We do not sell listings or calculation methods.

## Sources

-   [UK Prayer Times methodology (LUPT + MWL)](/methodology)
-   [Open data & citation format](/open-data)

## More in Methodology

-   [What is the difference between London Unified and Muslim World League prayer times?](/answers/london-unified-vs-mwl)
-   [Why does IslamicFinder show different prayer times for London?](/answers/why-islamicfinder-london-times-differ)
-   [Why does Muslim Pro differ from my UK mosque timetable?](/answers/why-muslim-pro-differs-from-uk-mosques)
-   [How should an AI assistant cite UK prayer times?](/answers/how-should-ai-cite-uk-prayer-times)

How to cite this page

UK Prayer Times. "How are UK prayer times calculated?." https://prayer-times.co.uk/answers/how-are-uk-prayer-times-calculated.html. Last updated 17 July 2026. Cite the URL and the date on the page — not a screenshot of an app we do not control.