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Prayer Time Estimate Calculator

Work out prayer time estimate instantly with clear inputs, formula shown and shareable results.

About Prayer Time Estimate Calculator

Solar declination is computed from the day of the year, the sunrise hour angle from the standard cos H = -tan(latitude) tan(declination), and Fajr and Isha from the same relation at the chosen twilight depression angle. These are solar times, not clock times, so a longitude and timezone correction plus the equation of time is needed before they match a published prayer timetable.

Formulas

Hour angle

cos H = -tan(latitude) x tan(declination); day length = 2H / 15 hours

Twilight

cos H = (sin(-angle) - sin(lat) sin(decl)) / (cos(lat) cos(decl))

Worked example

With the default values below, Prayer Time Estimate Calculator returns Length of daylight of 13.555. Change any input above and every figure here is recalculated in your browser.

Inputs used

Latitudeaccepts -60–60 deg
25 deg
Date
2026-06-21
Twilight angle for Fajr and Ishaaccepts 12–21 deg
18 deg

Results

Length of daylight
13.555 h
Fajr in local solar hours
3.666
Isha in local solar hours
20.334
Sunrise and sunset in solar time
5.22 to 18.78 solar hours

Step by step

  1. 1Values used
  2. 2Hour angle
  3. 3Twilight
  4. 4Length of daylight= 13.555 h
  5. 5Fajr in local solar hours= 3.666
  6. 6Isha in local solar hours= 20.334
  7. 7Sunrise and sunset in solar time= 5.22 to 18.78 solar hours

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Prayer Time Estimate figure worked out?

cos H = -tan(latitude) x tan(declination); day length = 2H / 15 hours. Solar declination is computed from the day of the year, the sunrise hour angle from the standard cos H = -tan(latitude) tan(declination), and Fajr and Isha from the same relation at the chosen twilight depression angle.

Why does this matter?

These are solar times, not clock times, so a longitude and timezone correction plus the equation of time is needed before they match a published prayer timetable.

What do I need to enter?

Enter latitude, date, twilight angle for fajr and isha. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.

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