In a constantly changing world--some things will never change--including these design rules featured by House Beautiful.
1. Dining Room Table
A 36-inch-wide rectangular table is perfect for conversation. A round table with a diameter of 48 inches seats six; a 60-inch round will handle eight standard dining chairs or 10 ballroom chairs.
2. Light Fixtures
How big should an overhead light fixture be? Just add the length and width of the room in feet, and whatever number you come up with is, in inches, your guide for the fixture's diameter. So a 15-by-20-foot room would need a 35-inch-wide chandelier.
3. Paint Coverage
One gallon of paint will cover about 400 square feet of wall.
4. Curtain Height
Mount curtains as high as possible to give the room more height, and let them break 1½ inches on the floor.
5. Kitchen Island
A kitchen island should be about 38 inches high—a little taller than the countertops—to be comfortable for prep.
6. Window Treatment Width
Curtains should be 2½ to 3 times the width of the window. So if you're doing two panels, each should be 1¼ to 1½ times the window width. Buy a rod that's 20 inches wider than your window so it extends 10 inches on either side. Your window will seem much wider than it really is.
7. Dining-Room Chandelier
The bottom of a dining-room chandelier should hang 36 inches above the table.
8. Light Switches
Install light switches 36 inches above the floor and 1½ to 2 inches to the side of the door trim.
9. Fabric for a Sofa
For a standard 84-inch sofa with exposed legs and a tight back, you'll need 14 yards of plain 54-inch-wide fabric. Add two yards for a skirt.
10. The Golden Ratio
From classical times to today, the golden ratio has always been the perfect proportion: 1 to 1.62.