Madrid is 4-5 hours ahead of Buenos Aires. Madrid uses Central European Time (CET/CEST) while Buenos Aires uses Argentina Time (ART, UTC-3). When it's 3:00 PM in Madrid, it's 10:00 AM or 11:00 AM in Buenos Aires.
Argentina does not observe daylight saving time, but Spain does. The difference is 5 hours during Central European Summer Time and 4 hours during CET.
Best calling time: 1:00 PM - 5:00 PM Madrid time. This corresponds to 8:00 AM - 12:00 PM in Buenos Aires, covering Argentine morning business hours.
Madrid and Buenos Aires have deep historical and cultural ties. Spain is a major investor in Argentina, and many Argentines have Spanish ancestry. Direct flights connect the cities in about 12 hours.