Most plans design the top last. Legs get figured out, joinery gets sorted, apron spacing gets locked in, and then somebody adds two inches of overhang and calls it done.
That's backwards. The top is the largest surface on the piece. It's the first thing anyone looks at. And in most furniture that feels slightly off but you can't say why, the top is the problem.
The shadow line
Here's what most people miss about overhang: it's not about leg clearance. It's about shadow.
When a top extends past the base, the underside casts a line across the apron. That shadow is a horizontal mark that separates the top from the structure below it. Without that line, top and base merge into one visual block. The piece reads heavier than it is.
You need at least 1.5 inches to get a visible shadow in typical room lighting. Below that, the line disappears and the top reads flush. Two inches is the common answer, and it's fine. But the point isn't the number. The point is: are you getting that separation?
On case pieces, the same rule applies, just smaller. A dresser with no top overhang looks like a box with a lid slapped on it. Even half an inch of overhang on the sides changes how the whole thing reads. It says someone designed a top, not just closed off the case.
Thickness
A 3/4-inch top is the default in most plans. It works for spans up to about 30 inches on solid wood and it's standard for sheet goods. For wider spans, 4/4 stock finished to just under an inch is appropriate.
But structural adequacy and visual correctness are different problems. A 1-inch top on a small side table with tapered legs looks like it's wearing a hat. A 3/4-inch top on a big dining table with a heavy base looks like it might bend if you lean on it.
The rule that actually works: err thinner, not thicker. Furniture reads better when the top is visually lighter than the base. The legs carry the visual weight. The top is just the plane your eye lands on.
Some reference points. Side table, 18 to 24 inches across: 3/4 inch is right, and if it reads a little thin, that's correct. Dining table, 36 to 40 inches: 7/8 to 1 inch. Case piece: match the case proportions, which usually means 3/4 inch. Workbench or desk: 1 to 1.5 inches, because those need to read as work surfaces, not furniture.
The Eames tables got this exactly right. Those tops are almost impossibly thin for their spans. That's not an accident. It's a statement: the structure below has already solved the problem. The top doesn't need to prove anything.
Edge treatment
The edge is where design vocabulary shows up most clearly, and where most people make their worst decisions.
A square edge is the most honest option. It shows the full thickness of the material. If the top is 3/4 inch, it looks like 3/4 inch. No tricks.
A round-over softens the visual weight. The eye follows the curve instead of reading the flat face, so the top looks thinner than it measures. On a dining table, it also means fewer bruised forearms. Functional and aesthetic at the same time.
A chamfer does something different. It catches light as a bright line at the transition. On dark species like walnut, a chamfer reads as deliberate. On light species, it can disappear. Chamfers are a slightly more assertive detail. They say the maker thought about the edge, not just the surface.
A bullnose adds visual weight and turns the edge into a feature. On traditional work, that reads as intentional. On contemporary work, it reads as 1997. Route a bullnose on something MCM-inspired and it will look like a Pottery Barn catalog from two decades ago.
If you're not sure, go square. A square edge with a light chamfer is the safest choice in furniture, and it's almost never wrong.
Reading the top in a plan
Three questions before you commit to any top dimension.
What's the overhang? If it's under 1.5 inches, you're losing the shadow line. Ask whether that's a deliberate choice or just a default nobody questioned.
What's the thickness relative to the base? Heavy base, thinner top. Light open base, the top can carry more visual weight. If the proportions feel wrong in the drawing, they will feel wrong in the room.
What does the edge say? The edge treatment should match the rest of the piece. Crisp machined legs with a soft bullnose edge will fight each other. Gentle curves with a hard chamfer will feel confused. The edge is a sentence in the same language as the legs.
One more thing
Changing a top dimension before you cut is a 30-second revision in your notes. Changing it after you've glued up the panel is a day of work and a lot of wasted material.
Design the top first. Or at least design it deliberately. It's the biggest surface on the piece, and it deserves more than two inches of default overhang and whatever thickness was left over.