This site works best in landscape, so turn your device sideways if you're on a mobile phone or tablet, then click the stamp to go full screen once the page loads!

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Interval Calculator

Click or tap on the letter for the lower or upper note of the
interval or an accidental to modify it, or choose an option below. Click on the stamp to go full screen.

Interval is an octave or greater Describe as compound interval Advanced mode. Allow extended range intervals!