Genesis 6:15 gives the exact dimensions God required for the ark Noah was to build: 300 cubits long, 50 cubits wide, and 30 cubits high. The verse is a set of construction instructions, given before the flood, that shows God planning carefully for the rescue of Noah’s family and the animals. God speaks these words directly to Noah, who is described as a righteous man in a corrupt generation.
This is how you shall make it. The length of the ship shall be three hundred cubits, its width fifty cubits, and its height thirty cubits.
Genesis 6:15 (WEB)
What Genesis 6:15 Means
The verse opens with “This is how you shall make it,” which tells you the instructions are specific and meant to be followed. God is not leaving the design to Noah’s imagination. The phrase “the length of the ship” refers to the longest dimension, and the three numbers give a shape that is long, fairly narrow in proportion, and tall enough to hold multiple decks. Most scholars take a cubit to be roughly 18 inches, which would make the ark something like 450 feet long, but the exact modern equivalent is debated, so the figures are better read as large and carefully proportioned than as precise engineering specs.
What the verse does not do is explain how Noah was to handle the seas, the weather, or the feeding of the animals. Those details come in other verses. Genesis 6:15 focuses on size and shape. It is a reminder that God’s plans for protection often come with clear, concrete steps, and that obedience usually means doing the ordinary work of building as well as trusting the outcome.
The Context of Genesis 6:15
Genesis belongs to the Torah, the first five books of the Hebrew Scriptures, and is traditionally attributed to Moses, though many scholars think it was shaped from older sources over time. The first readers were ancient Israelites who needed to understand where the world came from and why God dealt with humanity as he did. The flood story speaks to God’s judgment on violence and corruption, and also to his decision to preserve a remnant through a righteous man.
Just before verse 15, God declares that he will bring an end to all flesh because the earth is filled with violence. In the verses that follow, he commits to establishing a covenant with Noah and tells him to bring his family and the animals into the ship. Read in that sequence, the measurements are not an isolated building note. They are part of God’s act of judgment and mercy, showing that the same God who will destroy the wicked is also making a way of escape for those who trust him.
Key Phrases in Genesis 6:15
Hebrews 11:7
By faith, Noah, being warned about things not yet seen, moved with godly fear, prepared a ship for the saving of his house, through which he condemned the world, and became heir of the righteousness which is according to faith.
(WEB)
This verse describes Noah as moved by godly fear to prepare an ark, showing that his building was an act of faith in God’s warning. It helps explain why Genesis 6:15 reads as an act of trust rather than simple engineering.
Exodus 25:9
According to all that I show you, the pattern of the tabernacle, and the pattern of all of its furniture, even so you shall make it.
(WEB)
Here God gives Moses the pattern for the tabernacle and insists that it be made exactly as shown. The parallel reveals a consistent theme that God’s sacred works are built according to his specific design.
A Short Prayer From Genesis 6:15
Lord, you are the one who gives clear direction even when the path ahead looks uncertain. Help me to receive your instructions with humility and to act on them faithfully, one step at a time. When I feel overwhelmed by what I must build or carry, remind me that you have already measured the way and will sustain me as I follow. Give me patience with the work and trust in your purposes, especially when I cannot yet see the outcome. Amen.
