What is the significance of the number 40 in the Bible?

Forty appears repeatedly in Scripture to mark periods of testing, judgment, or preparation: 40 days and nights of rain in the flood, 40 years of Israel's wilderness wandering, 40 days of Moses on Sinai, and Jesus's 40 days of fasting and temptation in the wilderness.

The number 40 recurs throughout the Bible in connection with testing, transition, and preparation before a significant change. Rain fell "forty days and forty nights" during the flood (Genesis 7:12). After the Exodus, Israel wandered the wilderness for 40 years as consequence for their unbelief at Kadesh-barnea (Numbers 14:33-34), a full generation passing before entering the Promised Land. Moses spent 40 days on Mount Sinai receiving the Law (Exodus 24:18), and later fasted 40 days again after the golden calf incident (Deuteronomy 9:18). Elijah traveled 40 days to Horeb after fleeing Jezebel (1 Kings 19:8). Jonah warned Nineveh it had 40 days before judgment (Jonah 3:4). In the New Testament, Jesus fasted 40 days in the wilderness while being tempted by Satan before beginning his public ministry (Matthew 4:1-2), and appeared to his disciples over a 40-day period between his resurrection and ascension (Acts 1:3). While the Bible never explicitly defines the number's symbolism, its consistent association with periods of trial, waiting, or preparation before a new phase of God's plan is one of Scripture's most recognizable patterns.

Key Passages

Forty days and nights of rain

Genesis 7:12

¹² And the rain was upon the earth forty days and forty nights.

Forty years in the wilderness

Numbers 14:33-34

³³ And your children shall wander in the wilderness forty years, and bear your whoredoms, until your carcases be wasted in the wilderness. ³⁴ After the number of the days in which ye searched the land, even forty days, each day for a year, shall ye bear your iniquities, even forty years, and ye shall know my breach of promise.

Jesus fasts forty days

Matthew 4:1-2

¹ Then was Jesus led up of the Spirit into the wilderness to be tempted of the devil. ² And when he had fasted forty days and forty nights, he was afterward an hungred.