The Hebrew Calendar Compared to the Gregorian (Modern) Calendar

The Hebrew calendar was composed of 12 lunar months, each of which began when the thin crescent moon was first visible at sunset. They were composed of approximately 29/30 days and were built around the agricultural seasons. Apparently some of the names of the months were accommodated from Babylon following the time that the Israelites were exiled there.

Month	Hebrew Month	Gregorian (Modern) Month	Festivals	Biblical References
First Month	Abib (Preexile) Nisan (Postexile)	March–April	14th: Passover (Ex. 12:18; Lev. 23:5) 15th–21st: Unleavened Bread (Ex. 12:14–20; Lev. 23:6) 16th: First Fruits (Lev. 23:9–11)	Ex. 13:4; 23:15; 34:18; Deut. 16:1; Neh. 2:1; Est. 3:7 (cf. Gen. 8:13; Ex. 12:2, 18; 40:2, 17; Lev. 23:5; Num. 9:1; 20:1; 28:16; 33:3; Josh. 4:19; 1 Chron. 12:15; 27:2, 3; 2 Chron. 29:3, 17; 35:1; Ezra 6:19; 7:9; 8:31; 10:17; Est. 3:7, 12; Ezek. 29:17; 30:20; 45:18, 21; Dan. 10:4)
Second Month	Ziv (Preexile) Iyyar (Postexile)	April–May	14th: Later Passover (Num. 9:10–11)	1 Kings 6:1, 37 (cf. Gen. 7:11; 8:14; Ex. 16:1; Num. 1:1, 18; 9:11; 10:11; 1 Chron. 27:4; 2 Chron. 3:2; 30:2, 13, 15; Ezra 3:8)
Third Month	Sivan	May–June	4th: Pentecost [Feast of Weeks] (Lev. 23:15–16)	Est. 8:9 (cf. Ex. 19:1; 1 Chron. 27:5; 2 Chron. 15:10; 31:7; Ezek. 31:1)
Fourth Month	Tammuz	June–July		Ezek. 8:14 (cf. 2 Kings 25:3; 1 Chron. 27:7; Jer. 39:2; 52:6; Ezek. 1:1; Zech. 8:19)
Fifth Month	Ab	July–August		Not mentioned by name in the Bible (cf. Num. 33:38; 2 Kings 25:8; 1 Chron. 27:8; Ezra 7:8, 9; Jer. 1:3; 28:1; 52:12; Ezek. 20:1; Zech. 7:3, 5; 8:19)
Sixth Month	Elul	August–September		Neh. 6:15 (cf. 1 Chron. 27:9; Ezek. 8:1; Hag. 1:1, 15)
Seventh Month	Ethanim (Preexile) Tishri (Postexile)	September–October	1st: Trumpets (Lev. 23:24; Num. 29:1) 10th: Day of Atonement (Lev. 16:29–34; 23:27–32) 15th–21st: Booths (Lev. 23:34–40) 22nd: Solemn assembly (Lev. 23:36)	1 Kings 8:2 (cf. Gen. 8:4; Lev. 16:29; 23:24, 27, 34, 39, 41; 25:9; Num. 29:1, 7, 12; 2 Kings 25:25; 1 Chron. 27:10; 2 Chron. 5:3; 7:10; 31:7; Ezra 3:1, 6; Neh. 7:73; 8:2, 14; Jer. 28:17; 41:1; Ezek. 45:25; Hag. 2:1; Zech. 7:5; 8:19)
Eighth Month	Bul (Preexile) Marchesvan (Postexile)	October–November		1 Kings 6:38 (cf. 1 Kings 12:32, 33; 1 Chron. 27:11; Zech. 1:1)
Ninth Month	Chislev (Kislev)	November–December	25th: Dedication (John 10:22)	Neh. 1:1; Zech. 7:1 (cf. 1 Chron. 27:12; Ezra 10:9; Jer. 36:9, 22; Hag. 2:10, 18)
Tenth Month	Tebeth	December–January		Est. 2:16 (cf. Gen. 8:5; 2 Kings 25:1; 1 Chron. 27:13; Ezra 10:16; Jer. 39:1; 52:4; Ezek. 24:1; 29:1; 33:21; Zech. 8:19)
Eleventh Month	Shebat	January–February		Zech. 1:7 (cf. Deut. 1:3; 1 Chron. 27:14)
Twelfth Month	Adar*	February–March		Ezra 6:15; Est. 3:7, 13; 8:12; 9:1, 15, 17, 19, 21 (cf. 2 Kings 25:27; 1 Chron. 27:15; Jer. 52:31; Ezek. 32:1; 32:17)

*Periodically, a 13th month was added so that the lunar calendar would account for the entire solar year.