When measuring each wall of your space, including all fireplaces, windows, doors and closets, draw out a floor plan on graph paper using one square inch to represent each square foot of space. Remember to include spaces that adjoin the main area, and indicate where they are located.
It is important that you take these measurements along with you when shopping for furniture. Furniture in showrooms more often than not appears smaller than it will in your space. You can create your own changeable furniture template by drawing the furniture pieces on card stock and cutting them out for positioning on the floor plan.
Be sure to measure accurately and double check your measurements—a small mistake could cost you time and money

Walking paths through rooms and around furniture should be 36 to 42 inches wide. High-traffic areas, such as hallways and entryways, should be at least 4 feet across. 

When creating a seating area, plan for more than one way to access the area, keeping in mind that, ideally, people should not have to walk in front of those who are seated. 

Try to avoid routing traffic through small living rooms.

Space planning tip: Using angles in design can be dynamic and inviting. When angling furniture into a corner, keep in mind that something needs to be placed behind the furniture to fill the corner gap, such as a table with art and a lamp, or a tall, full tree (silk or live). 

 Allow 16 to 20 inches between the cocktail or coffee table and the front of the sofa.

 The maximum distance for comfortable viewing of a standard box TV is 10 feet. 

Use 36 by 84 inches as baseline dimensions for a sofa. This size will fit well in most homes and apartments. 

Furniture should be 4 to 6 inches from a wall to allow for plug-ins and baseboards and to prevent scratching. Leave a little more room for couches, especially if you have long window treatments behind them. 

Sofas and chairs in a conversation grouping should be placed about an arm’s length from each other. An arrangement should be contained within 14 feet to function as a conversation area. 

A minimum of 35 inches back height is ideal for a sofa and chairs in rooms with vaulted ceilings.

 Tables should be at the arm height of the sofa or chair they are next to or slightly lower (never higher) for optimal fit and function. This also applies to bedside tables and chests.

 The bottom of a lampshade should be at your eye level when you are seated. 

Allow 30 to 36 inches beyond a dining room table for chairs to be pulled in and out easily.

 Allow at least 24 inches between the back of a dining chair and a buffet or china cabinet. 

Keep heights of upholstered furniture within 6 inches of each other for comfortable visual appeal.

 Allow about 24 inches of table length for each guest. If you have to squeeze in an extra guest or two, reduce the space to about 20 inches per person.

 The diameter of a chandelier should equal the sum of the length and width of the room. For example, if the room is 19 feet by 19 feet, the ideal chandelier is 38 inches around. 

A nightstand should be about 6 inches from the side of the bed. 

To create a great look with a large area rug, choose a rug that allows 12 to 18 inches from each wall. 

When placing a rug under a dining room table, allow 24 inches from the edge of the table to the end of the rug. Most dining rooms require at least an 8-by-10 rug.