I answered you in your other thread ... http://forums.gardenweb.com/forums/load/sqfoot/msg061626501159.html?12

There are 144 square inches in a square foot (12 x 12 = 144)

There is a great FAQ section right here on GardenWeb that visually shows the placement per square foot: GardenWeb: What are recommended plant spacings?

I hope this helps.

Rachel
Graphic Muse's Garden Spot

One more thing...your beds do not have to be 4x4. Some of mine are larger and some smaller.

Here is a link that might be useful: The Corner Yard

Build the box to the demension that suits you (4x4 or 2x8 or 3x4 or 2x4, etc.) then make your grids. And then and only then figure out spacing using the handy dandy FAQ.

You are over thinking this really. Many times I do not have a plant in every square anyway, for several reasons.

When I was asking about how many inches were in one 1' x 1' square foot I wasn't asking about how many square inches are in 1' x 1' square. I was just asking how many NORMAL inches are in a square foot square. The reason I ask for this info is because the seed packets I have specify how far apart to thin the seedlings to, but NOT in square inches in regular inches.

As said before, I'm not very familiar with the square foot
system of measurement, so when you say "there are 144 square inches in a square foot" unfortunately that's clear-as-mud to me.

I appreciate the planting charts given, however they don't make sense to me because all of the recommendations given
with planting guidelines are in square feet, which again is clear-as-mud to me.

Got you, took a while, if the packet says thin to 3 inches a row, space rows 12 inches appart, you take the spaceing as your base, so the plants are 3 inches apart all round.
4 inch spacing, 4 all round
so a big plant, say cabbage says thin to 18 inches, then therotically, you should give 18 inches all round, I don't! I give them 9" and stagger the rows, as a lot of that space is loose leaves and cuts down on the weeds.
I also don't plant a whole Sq foot of say carrot at a time except at the beginning of the season, as with the best will in the world I can't eat 16 of them every 2 weeks, so I plant 8, then 8 and if any arn't showing I replace them.
if you can afford it, I would buy the book, as when you go through it, it all starts to come clear? (amazon was the best price I got and at the mo, I think they have a 2 day free shipping, don't know on what, but maybe worth looking at) take a lot of stuff in the book with a pinch of salt (such as mel's mix...sacrilege...burn the witch!), but a really easy read, and some good money saving ideas.
hope I got what you meant?

Maybe this can help. Click on the image to see it big enough to read. It shows regular inches (which are lines) compared to square inches (which are boxes).

Hopefully it will help this all make a little more sense.

Here is a link that might be useful: inches vs square inches

Each square foot is 12 inches x 12 inches.

If your seed packet says to plant seeds 12 inches apart, then you plant one plant per square. If 6 inch spacing = 4 per square. If 4 inch spacing = 9 per square. If 3 inch spacing = 16 per square.

Here is a link that might be useful: GrafixMuse's Garden Spot