How much younger or older were Abu Bakr As-Siddeeq, ʻUmar ibn Al-Khattaab and ʻUthmaan ibn ʻAffaan, may Allaah be pleased with them, than Muhammad, sallallaahu 'alayhi wa sallam?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger.

Abu Bakr As-Siddeeq was the eldest among the Rightly-Guided Caliphs, then comes ʻUthmaan ibn ʻAffaan, and then comes ʻUmar ibn Al-Khattaab all. They were born before the Hijri calendar was introduced and adopted. After the Year of the Elephant, in which the Prophet was born, the Arabs used that year as a reference in dating events.

As-Suyooti wrote about Abu Bakr, "He was born two years and a few months after the birth of the Prophet ." [Taareekh Al-Khulafaa']

He wrote about ʻUmar ibn Al-Khattaab, "ʻUmar was born 13 years after the Year of the Elephant."

He wrote about ʻUthmaan ibn ʻAffaan, "He was born on the sixth year after the Year of the Elephant."

There were also other statements cited about the exact dates of their birth.

Allaah knows best.