Formula One postponed the Australian and Chinese Grands Prix on Tuesday due to the COVID-19 pandemic, with Bahrain now set to open the season on March 28.
Italy's Imola circuit was added to the 23-round calendar as the second race on April 18, with the third slot on May 2 still to be confirmed but expected to be filled by Portugal's Algarve circuit.
Australia was given a new date of Nov. 21 for the race in Melbourne.
China was not listed on the revised calendar but Formula One sources said it would be slotted in if circumstances allowed and another race dropped off. The calendar will not stretch beyond 23 races.
Both the Australian and Chinese races were cancelled entirely last year as the pandemic ripped up the sporting calendar, with the season reduced to 17 grands prix in Europe and the Middle East.
"We are pleased to confirm that the number of races planned for the season remains unchanged," said Formula One's new chief executive Stefano Domenicali in a statement.
"The global pandemic has not yet allowed life to return to normal, but we showed in 2020 that we can race safely as the first international sport to return and we have the experience and plans in place to deliver on our season.
"It is great news that we have already been able to agree a rescheduled date for the Australian Grand Prix in November and are continuing to work with our Chinese colleagues to find a solution to race there in 2021 if something changes."
Revised 2021 Formula One calendar
March 28 - Bahrain, Sakhir
April 18 - Italy, Imola
May 2 - To be confirmed
May 9 - Spain, Barcelona
May 23 - Monaco
June 6 - Azerbaijan, Baku
June 13 - Canada, Montreal
June 27 - France, Le Castellet
July 4 - Austria, Spielberg
July 18 - Britain, Silverstone
Aug 1 - Hungary, Budapest
Aug 29 - Belgium, Spa-Francorchamps
Sept 5 - Netherlands, Zandvoort
Sept 12 - Italy, Monza
Sept 26 - Russia, Sochi
Oct 3 - Singapore
Oct 10 - Japan, Suzuka
Oct 24 - United States, Austin
Oct 31 - Mexico, Mexico City
Nov 7 - Brazil, Sao Paulo
Nov 21 - Australia, Melbourne
Dec 5 - Saudi Arabia, Jeddah
Dec 12 - Abu Dhabi, Yas Marina