Samrat Yantra is another important instrument in the Jaipur observatory, Jantar Mantar. It is called the Samrat Yantra because it is the biggest instrument at Jantar Mantar, Jaipur. It is also famous for its accurate construction. Time can be calculated by observing the solar system. This instrument can calculate local time that is correct upto 2 seconds. The gnomon of this sundial is 90 feet high. There are niches in the wall so that the storm does not affect the instrument.

The gnomon of the Samrat Yantra is located on the right-angled wall and the hypotenuse has steps to climb up. This also has a scale, which is helpful in finding the altitude of the sun. The hypotenuse points out towards a pole. This pole has on its either side a masonary quadrant. The sides of the quadrant are marked in hours, minutes and seconds. On the scale 1 minute has been divided into 30 parts. This division helps in measuring the divisions accurately.

There are steps near the quadrant to enable the observers` climb up to the dial to check the time.