Enter the room, its windows and its way out. You get the International Residential Code's tests for a bedroom one by one: the floor area, the width, the ceiling, the escape opening, the light and the air, and which ones fail.
Your room
Yes: this 12′ × 10′ room meets the IRC’s bedroom rules120 sq ft · 8′ ceiling · a 6 sq ft escape window — your city’s code may ask more
Quick answer: under the International Residential Code a bedroom needs 70 sq ft of floor, 7′ in every direction and a 7′ ceiling; window glass of 8% of the floor, half of that (4%) able to open; and a way out in a fire: a window with a 5.7 sq ft clear opening (5 sq ft near the ground), at least 24″ high and 20″ wide, its bottom no more than 44″ above the floor, or a door to the outside. The IRC names no closet. Your city’s code can ask more.
How to use the bedroom checker
- Measure the room: its length and width, and the ceiling. Under a sloped ceiling, give its highest point and its lowest, at the wall.
- Measure the windows: the glass in all of them, and how much of it opens. For the escape window, open it fully and measure the clear opening it leaves, and the height of its bottom above the floor.
- You get each of the code’s tests with its section number, ✓ or ✗, and the room drawn from above to scale. If the window fails, the window size finder lists the sizes that pass.
The rules, and where they come from
From the 2021 International Residential Code, the model code that US states and cities adopt, often with changes. The text quoted is from Colorado’s adoption, which takes it “without amendments”. The 2024 edition keeps every number below and renumbers the sections: room areas R312, ceiling height R313, escape openings R319, light and air R325.
Size. R304.1: “Habitable rooms shall have a floor area of not less than 70 square feet.” R304.2: “not less than 7 feet … in any horizontal dimension.” R304.3: under a sloping ceiling, floor with less than 5 feet of headroom “shall not be considered as contributing to the minimum required habitable area”.
Ceiling. R305.1: “a ceiling height of not less than 7 feet”. A sloped ceiling passes when the 70 sq ft has at least 5 feet over it and half of it, 35 sq ft, at least 7 feet. In basements, beams and ducts may come down to 6′4″.
Light and air. R303.1: “an aggregate glazing area of not less than 8 percent of the floor area … The openable area to the outdoors shall be not less than 4 percent”. Fixed glass is allowed with mechanical ventilation of 0.35 air changes an hour, and no glass at all if lights also give 6 footcandles.
A way out. R310.1: “every sleeping room shall have not less than one operable emergency escape and rescue opening”. R310.2: a net clear opening of 5.7 sq ft (5 sq ft when its bottom is within 44″ of the ground outside), at least 24″ high and 20″ wide, its bottom “not greater than 44 inches” above the floor. R310.3: a door counts if it is “a side-hinged door or a sliding door”. Below ground, R310.4 adds a well of at least 9 sq ft, 36″ each way, with a ladder if it is deeper than 44″.
Not the garage. R302.5.1: “Openings from a private garage directly into a room used for sleeping purposes shall not be permitted.”
What a city adds. The City of Chico, California counts a room as a bedroom only “if it contains a closet, alcove, indentation or wing wall which creates an area greater than 12 inches in depth”, and its handout asks for a 7′6″ ceiling. Ask your building department before you list or convert a room.
The smallest escape window that passes
| Clear width | Clear height for 5.7 sq ft | Near the ground, 5 sq ft |
|---|---|---|
| 20″ | 41.1″ | 36″ |
| 22″ | 37.4″ | 32.8″ |
| 24″ | 34.2″ | 30″ |
| 28″ | 29.4″ | 25.8″ |
| 30″ | 27.4″ | 24″ |
| 32″ | 25.7″ | 24″ |
| 36″ | 24″ | 24″ |
The clear opening, not the glass or the frame. The 20″ and 24″ minimums together make only 3.33 sq ft, so one of them has to grow.
Glass and opening for each room size
| Room | Floor | Glass, 8% | Opens, 4% |
|---|---|---|---|
| 10′ × 7′ | 70 sq ft | 5.6 sq ft | 2.8 sq ft |
| 9′ × 8′ | 72 sq ft | 5.76 sq ft | 2.88 sq ft |
| 10′ × 10′ | 100 sq ft | 8 sq ft | 4 sq ft |
| 12′ × 10′ | 120 sq ft | 9.6 sq ft | 4.8 sq ft |
| 12′ × 12′ | 144 sq ft | 11.52 sq ft | 5.76 sq ft |
| 14′ × 12′ | 168 sq ft | 13.44 sq ft | 6.72 sq ft |
Worked examples
Yes: this 12′ × 10′ room meets the IRC’s bedroom rules: 120 sq ft, an 8′ ceiling, 12 sq ft of glass and a window opening 24 × 36″ clear (6 sq ft) with its bottom 36″ up.
Yes: this 10′ × 7′ room meets the IRC’s bedroom rules: 70 sq ft and 7′ wide, the smallest the code allows.
Not a bedroom yet: the escape opening fails: 24 × 34″ clear is 5.67 sq ft, just under 5.7. The same window near the ground passes, where 5 sq ft is enough.
An attic room 12′ × 10′, its ceiling rising from 4′ at the wall to 8′: Not a bedroom yet: the ceiling fails. 90 sq ft has 5′ of headroom, so the floor counts, but only 30 sq ft has 7′, and the code wants 35.
Common mistakes
- Measuring the glass for the escape window. What counts is the clear opening the open window leaves. A double-hung window opens about half its height.
- Counting the floor under a low slope. Under 5′ of headroom the floor is not room area.
- A window too high. A bottom more than 44″ above the floor fails, however big the opening.
- Taking a listing’s word for it. The IRC sets the floor; your city, your county and the person writing the listing may each use other rules.
More on bedrooms at Dreamy Home Style
- Attic bedroom ideas
- Small bedroom ideas
- Small guest bedroom ideas
- Guest room ideas
- Cozy ideas for unfinished basements
Laying out the furniture? The bedroom layout planner draws it to scale, and the free 2D floor planner draws the whole floor.
Bedroom questions
What is the smallest a bedroom can be?
70 sq ft of floor and 7′ in every direction (IRC R304.1 and R304.2), so a 10 × 7′ room is the smallest that passes, with a 7′ ceiling.
What is the minimum bedroom size?
70 square feet and no side under 7 feet, under the International Residential Code. Some cities ask more; check your local code.
Does a bedroom need a window?
It needs a way out in a fire: a window with a 5.7 sq ft clear opening (5 near the ground), or a side-hinged or sliding door to the outside (R310). It also needs glass of 8% of the floor, unless lights and mechanical ventilation stand in (R303.1).
Does a bedroom need a closet?
Not under the International Residential Code, which names no closet. Some cities do: Chico, California counts a room as a bedroom only with a closet, alcove or wing wall over 12″ deep.
What is considered a bedroom?
In the IRC, a room used for sleeping that passes the habitable room tests (70 sq ft, 7′ each way, a 7′ ceiling, light and air) and has an emergency escape opening, with no door straight into a garage.
What are the requirements for a basement bedroom?
The same, and the escape opening is in the bedroom itself: “Where basements contain one or more sleeping rooms, an emergency escape and rescue opening shall be required in each sleeping room” (R310.1). Below ground it needs a 9 sq ft well, 36″ each way, with a ladder if deeper than 44″.
How big does an egress window need to be?
A clear opening of 5.7 sq ft (5 sq ft near the ground), at least 24″ high and 20″ wide, its bottom no more than 44″ above the floor (R310.2).