How Many Pennies Can Fit In One Square Foot (1SF)

The answer to how many pennies can fit in one square foot (1 SF) depends on what reason is behind that question:

  • simple curiosity?

  • planning a project with pennies?

  • any minimum space required between pennies?

  • what pattern?

  • are there sides to the square foot and no penny can overlap any edge?

  • other.

Let's start with a piece of cardboard that measures 12 by 12 inches, which is exactly 1 SF. As you can see in the pictures, the tape measure shows we have 12 in. on both sides (even though it may be hard to see the small numbers).

12x12 in. cardboard showing tape measure at 12 inches.
One square foot cardboard.

We start placing pennies on the edge of this 12 in. cardboard and it results in a perfect fit: 16 pennies next to each other measure exactly 12 inches (one foot) because the diameter of a penny is .75 in. (or 3/4 of an inch).

By the way, as you can see, we used all brand new pennies for this demonstration.

16 pennies fit on the side of a 12 inch cardboard.1 SF cardboard and 16 pennies on its edge.

We added 15 more pennies to 'fill' the other side of the square cardboard as you can see here:

2 sides of a square foot cardboard having pennies on them.

Simple math can tell us how many pennies fit in one square foot in this straight pattern (16x16=256) without actually filling the square cardboard with pennies.

We decided to do it anyway in order to show other details and for you to see how beautiful it looks. 
Here we go, adding row after row of 16 pennies each. 

Worth mentioning here is that the pennies do touch each other. If a gap/space is required all around each penny (say for grout), changes must be made.   

Filling up a square foot area with brand new shiny uncirculated pennies.Slowly adding up pennies...

So, how many pennies can fit in one square foot?
256 pennies per square foot in straight rows.

No penny overlaps any edge and there's no space left whatsoever - at least that's what math tells us. If you see slight imperfections in the picture below is because we placed all 256 pennies by hand and they are just sitting there (not glued).

If a penny was square shaped (instead of round) with a .75 in. side, the cardboard below would be completely covered by 256 square pennies. But because the penny is round, you can see the cardboard in between pennies.

Notice the empty area between any 4 pennies is quite big and has 4 rounded sides
 (more on this later).

After carefully placing every penny by hand, here it is: 16 rows of 16 pennies each.

Square foot cardboard filled with 256 pennies in straight rows.16 pennies per straight row x 16 rows = 256 pennies

Here's a close-up on a corner of the square cardboard. Even though the pennies are in contact with each other, there's still quite some room in between them and that's due to the straight rows pattern/layout. 

Close-up on straight rows of pennies showing empty room in between them.Close-up on straight rows of pennies.