A standard window sizes chart helps contractors, DIYers, and homeowners quickly find window dimensions and rough opening sizes for framing. Select a window type below, toggle between inches and centimeters, and instantly see the rough opening formula applied to every common size.
Double-Hung Window Sizes
| Code | Window Size | Rough Opening |
|---|
Rough Opening Formula
Width
RO Width = Window Width + 1"
(+½" each side for shimming)
Height
RO Height = Window Height + ½"
(+½" top for shimming)
Note: Some manufacturers specify their own rough opening — always check the installation instructions that come with your specific window unit.
Room-by-Room Window Recommendations
Typical window types and sizes by room
| Room | Recommended Type | Typical Size |
|---|
Energy Efficiency Guide
U-Factor (Insulation)
Lower = better insulation. ENERGY STAR requires ≤ 0.30 in most climate zones.
SHGC (Solar Heat Gain)
Lower blocks more solar heat. Higher allows passive solar gain — useful on south-facing windows in cold climates.
Triple-pane glass — U-factor typically 0.15–0.20, best for very cold climates but adds weight and cost.
Low-E coating — microscopically thin metallic layer that reflects infrared heat; reduces both U-factor and SHGC.
Gas fill (argon/krypton) — fills the space between panes to reduce conduction; argon is most common, krypton is better but costlier.
Frame material — vinyl and fiberglass frames insulate better than aluminum; wood has good insulation but requires more maintenance.
How to Use the Standard Window Sizes Chart
This free standard window sizes chart lists common window dimensions for every major window type, along with the rough opening dimensions needed for framing. Whether you're replacing an existing window or framing a new opening, use this chart to plan your project accurately.
Step 1: Select Your Window Type
Click the tab for your window type: Double-Hung (the most common residential window, with two sashes that slide vertically), Casement (hinged at the side, opens outward with a crank), Sliding (panels slide horizontally), Picture (fixed, non-opening window for maximum light), or Bay (three-panel projecting window). Each type has its own standard sizes used by major manufacturers.
Step 2: Read the Window Size Code
Window sizes are typically expressed as a four-digit code where the first two digits are the width and the last two are the height, both in whole inches. A 3046 window is 30 inches wide by 46 inches tall. This notation is used across Andersen, Pella, Marvin, and most other major window manufacturers, though exact unit dimensions may vary slightly between brands.
Step 3: Find the Rough Opening
The rough opening is the framed hole in the wall, not the window itself. The standard rough opening formula adds 1 inch to the width (½ inch per side for shimming) and ½ inch to the height (½ inch at the top). This small gap allows you to level and plumb the window during installation. Some manufacturers specify different tolerances — always check the installation guide for your specific window unit.
Step 4: Toggle Units
Click inches or cm to switch between imperial and metric measurements. All window sizes and rough openings update instantly. US construction primarily uses inches; metric is the standard in most other countries and is increasingly used on commercial projects.
Choosing the Right Window Size
Standard window sizes are designed to fit between wall studs spaced 16 inches on center. A typical stud bay is about 14.5 inches clear between studs — windows wider than one bay require a header beam sized to carry the load. For egress windows (required in bedrooms and finished basements), the minimum opening is typically 5.7 square feet, with a minimum width of 20 inches and height of 24 inches — though local codes vary, so always verify with your building department.
Frequently Asked Questions
Is this window size chart free?
Yes, completely free with no account required. All data is built into the page and works offline — nothing is sent to any server.
Is my data private?
Yes. Everything runs entirely in your browser. No data ever leaves your device.
What is a rough opening for a window?
A rough opening is the framed hole in the wall where the window unit sits. It is slightly larger than the window itself — typically 1 inch wider (1/2 inch per side) and 1/2 inch taller — to allow for leveling, shimming, and a small expansion gap.
How do I read window size codes like 2446 or 3046?
Standard window size codes combine width and height in inches. The first two digits are the width and the last two are the height, both in whole inches. So a 2446 window is 24 inches wide by 46 inches tall, and a 3046 window is 30 inches wide by 46 inches tall.
What is the most common double-hung window size?
The most common double-hung window sizes for residential construction are 2446 (24×46 in) and 3046 (30×46 in). These fit standard stud bays and provide good ventilation and natural light for bedrooms, living rooms, and kitchens.
What is the difference between window size and rough opening?
The window size (or unit size) is the actual dimension of the factory-built window frame. The rough opening is larger — typically the window width plus 1 inch and the window height plus 1/2 inch — to allow for shimming, leveling, and caulking during installation.
What window type is best for ventilation?
Casement windows typically offer the best ventilation because the entire sash opens, directing airflow into the room. Double-hung windows open top or bottom but only expose half the opening at once. Sliding windows open half the frame. For maximum airflow, choose casement or awning windows.
What do U-factor and SHGC mean for windows?
U-factor measures how well a window insulates — lower is better (good windows range from 0.17 to 0.30). SHGC (Solar Heat Gain Coefficient) measures how much solar heat passes through — lower values block more heat (0.25–0.40 is ideal for hot climates; higher for cold climates where passive solar gain is helpful).