How to Convert Biblical Measurements

Learn to calculate the measurements of Noah's Ark

Noah's ark sailing through stormy waters with thunderous sky above

Getty Images / Eric Thomas

One of comedian Bill Cosby's most hilarious routines features a conversation between God and Noah about building an ark. After getting detailed instructions, a puzzled Noah asks God: "What's a cubit?" and God responds that He doesn't know either. Too bad they couldn't get help from archaeologists on how to count their cubits today.

Learn the Modern Terms for Biblical Measurements

"Cubits," "fingers," "palms," "spans," "baths," "homers," "ephahs," and "seahs" are among ancient forms of biblical measurements. Thanks to decades of archaeological digs, scholars have been able to determine the approximate size of most of these measurements according to contemporary standards.

Measure Noah's Ark in Cubits

For example, in Genesis 6:14-15, God tells Noah to build the ark 300 cubits long, 30 cubits high and 50 cubits wide. By comparing various ancient artifacts, a cubit has been found to equal about 18 inches, according to National Geographic's atlas, The Biblical World. So let's do the math:

  • 300 X 18 = 5,400 inches, which amounts to 450 feet or a little more than 137 meters in length
  • 30 X 18 = 540 inches, or 37.5 feet or just under 11.5 meters in height
  • 50 X 18 = 900 inches, or 75 feet or slightly less than 23 meters

So by converting biblical measurements, we end up with an ark that's 540 feet long, 37.5 feet high and 75 feet wide. Whether that's large enough to carry two of each species is a question for theologians, science fiction writers, or physicists who specialize in quantum state mechanics.

Use Body Parts for Biblical Measurements

As ancient civilizations progressed to the need for keeping account of things, people used parts of the body as the quickest and easiest way to measure something. After sizing up artifacts according to both ancient and contemporary measurements, they've discovered that:

  • A "finger" equals about three-quarters of an inch (roughly the width of an adult human finger)
  • A "palm" equals about 3 inches or the size across a human hand
  • A "span" equals about 9 inches, or the width of an extended thumb and four fingers

Calculate More Difficult, Biblical Measurements for Volume

Length, width, and height have been calculated by scholars with some common agreement, but measures of the volume have eluded accuracy for some time.

For example, in an essay titled "Bible Weights, Measures, and Monetary Values," Tom Edwards writes about how many estimates exist for a dry measure known as a "homer:"

"For instance, a Homer's liquid capacity (though normally seen as a dry measure) has been estimated at these various amounts: 120 gallons (calculated from footnote in New Jerusalem Bible); 90 gallons (Halley; I.S.B.E.); 84 gallons (Dummelow, One Volume Bible Commentary); 75 gallons (Unger, old edit.); 58.1 gallons (Zondervan Pictorial Encyclopedia of the Bible); and about 45 gallons (Harper's Bible Dictionary). And we need to also realize that weights, measurements, and monetary values often varied from one place to the next, and from one time period to another."

Ezekiel 45:11 describes an "ephah" as being one-tenth of a homer. But is that one-tenth of 120 gallons, or 90 or 84 or 75 or ...? In some translations of Genesis 18: 1-11, when three angels come to visit, Abraham instructs Sarah to make bread using three "seahs" of flour, which Edwards describes as one-third of an ephah, or 6.66 dry quarts.

Using Ancient Pottery to Measure Volume

Ancient pottery offers the best clues for archaeologists to determine some of these biblical volume capacities, according to Edwards and other sources. Pottery labeled "bath" (that was dug up in Tell Beit Mirsim in Jordan) has been found to hold about 5 gallons, comparable to similar containers of the Greco-Roman era with capacities of 5.68 gallons. Since Ezekiel 45:11 equates the "bath" (liquid measure) with the "ephah" (dry measure), the best estimate for this volume would be about 5.8 gallons (22 liters). Ergo, a homer equals roughly 58 gallons.

So according to these measures, if Sarah mixed up three "seahs" of flour, she used nearly 5 gallons of flour to make bread for Abraham's three angelic visitors. There must have been plenty of leftovers to feed their family — unless angels have bottomless appetites.

Relevant Bible Passages

Genesis 6:14-15
"Make yourself an ark of cypress wood; make rooms in the ark, and cover it inside and out with pitch. This is how you are to make it: the length of the ark three hundred cubits, its width fifty cubits, and its height thirty cubits."
Ezekiel 45:11
"The ephah and the bath shall be of the same measure, the bath containing one-tenth of a homer, and the ephah one-tenth of a homer; the homer shall be the standard measure."


  • The Biblical World: An Illustrated Atlas (National Geographic 2007).
  • "Biblical Weights, Measures, and Monetary Values," by Tom Edwards, Spirit
  • The New Oxford Annotated Bible with Apocrypha, New Revised Standard Version (Oxford University Press). New Revised Standard Version Bible, copyright 1989, Division of Christian Education of the National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved.
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Your Citation
Astle, Cynthia. "How to Convert Biblical Measurements." Learn Religions, Apr. 5, 2023, Astle, Cynthia. (2023, April 5). How to Convert Biblical Measurements. Retrieved from Astle, Cynthia. "How to Convert Biblical Measurements." Learn Religions. (accessed June 9, 2023).