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   Accuracy

Where do you get the zmanim from?
All MyZmanim times are calculated on-site using algorithms that were assembled by our staff exclusively for this purpose. We've done extensive research and conducted independent studies to make our algorithms as accurate as possible. To read our haskamos, click here.

Can I rely on zmanim to the last moment?
Although our times are compiled to the highest accuracy standards, one should not rely on zmanim to the last moment. Many factors influence the zmanim and some cannot practically be measured or forecasted. It goes without saying that zmanim can only be as accurate as your clock, so having an accurate clock is important.

Elevation
Hanetz and shekia (sunrise and sunset times) are affected by elevation.

To keep things compact, MyZmanim indicates elevation profiles in an abridged format: "your elevation/horizon elevation". For example, "Elevated 800/100 meters" means the zmanim were computed for a location that is elevated 800 meters above sea level with a horizon that is elevated 100 meters above sea level. In contrast, "level region elevated 800 meters" means the zmanim are for a location that is at the same elevation as the horizon; both are elevated 800 meters above sea level.

Shaos zmaniyos of the Gra & Baal HaTanya are based on the level region sunrise/sunset rather than the elevated above horizon sunrise/sunset.

Rounding
In the MyZmanim App and the MyZmanim Calendar, where seconds are not included, all times for Sunrise, Earliest Talis, Earliest Mincha and Nightfall (all opinions) were rounded later. Accordingly, a listing of "6:12" means "before 6:12" (between 6:11 and 6:12). All other Zmanim times have been rounded earlier. As such, a listing of "5:36" means "after 5:36".

International Date Line
The displayed Jewish date and weekday have been determined based on the fact that Shabbos is on Saturday. Note, however, that this is not always the case. In some parts of the world, such as New Zealand and Japan, Shabbos may be on Sunday. In Hawaii Shabbos may be on Friday. This is because the Torah draws the International Date Line differently than the secular community.

Nonexistent Zmanim
In some parts of the world, there are days when sunrise, sunset or other zmanim do not occur. In such cases, MyZmanim displays "X:XX" in place of a time.

See also
-- Computation by degrees explained
-- Sources for tzes 3 stars and Earliest talis