Home / Tools / Window Fit Checker
Measure before you order
Window AC Fit Checker: Will It Fit My Window?
Enter your window's width and how far the lower sash opens. We check both Classic America window units against their published fit range and draw the result to scale.
- Both models checked at once
- Drawn to scale
- Room size check included
Your window
Measure inside the frame, sash fully raised.
Window type
The room
Floor
Grounded 3-prong outlet within reach of the cord?
How to measure
Three measurements, two minutes
- 1
Open the lower sash fully
Raise it as high as it goes. Remove any screen or insert that sits in the opening.
- 2
Measure the width
From the inside of one side jamb to the other, at the sill. Record the narrowest point.
- 3
Measure the opening height
From the sill to the bottom of the raised sash. This is the height the unit slides into.
- 4
Find the outlet
A grounded 3-prong outlet near the window. Window units plug straight into the wall; never into an extension cord.
Reference
Window AC fit and size specifications
| Model | Window width | Min. opening | Unit size (W x D x H) | Weight | Room size | Price |
|---|---|---|---|---|---|---|
| 8,000 BTU window AC TWC-08CRD1/L0U | 23 to 36 in | 14.5 in | 18.58 x 15.59 x 13.31 in | 47.4 lb | 300–350 sq ft | $280 |
| 12,000 BTU window AC TWC-12CRD1/L0U | 26 to 36 in | 16 in | 19.76 x 21.5 x 15.16 in | 70.55 lb | 400–450 sq ft | $380 |
From the manufacturer spec sheet (TWC-08/12). Room size is the ENERGY STAR range for each capacity.
Want your window back?
A mini split heats too, and leaves the window free
A ductless mini split mounts on the wall, runs from 27 dB indoors on the 9,000 BTU model and heats as well as cools. The 115V models suit most bedrooms and offices.
- Up to 23 SEER2 on 115V
- Indoor and outdoor unit in one box
- Free shipping, 30-day money back
Questions
Window AC fit FAQ
Will a window AC fit a sliding or casement window?
Classic America window units are designed for double-hung windows, where the lower sash slides up and holds the unit in place. Sliding and casement windows need a different kind of air conditioner, so consider a ductless mini split for those rooms. The Size Finder will match one to the room.
What if my window is narrower than the minimum?
The unit will not sit securely and the side panels cannot seal the gap. The 8,000 BTU model fits the narrowest windows, from 23 inches.
What if my window is wider than 36 inches?
The included side panels will not close the whole gap. Some owners fill the extra width with a rigid insulated panel, but the unit must still be supported securely and sealed against weather.
Can I install it on a second floor?
Yes, with extra care. The 12,000 BTU unit weighs 70.55 lb. Use two people, make sure the sill is sound and use a support bracket or professional installation on upper floors.
What if it does not fit after all?
Every order has a 30-day money back guarantee for units that are uninstalled and in original condition. Measure with the checker above before you open the box, and see shipping and returns for the details.
Can I use an extension cord?
No. Plug the unit directly into a grounded 3-prong outlet. If the nearest outlet is out of reach, have an electrician add one.
From the blog
Window AC reading before you measure
Fit is the first question. These cover the rest: whether a window unit is the right call, how to cool several rooms with them, and what the smart features save.
Start here13 min readAug 1st 2025
Mini Split vs. Smart Window AC: Which Is Right for Your Space?
Install, noise, heating and running costs compared, so you know a window unit is the right type before you measure for one.
Read the article
210 min readJun 30th 2025
Creating Smart Cooling Zones with Multiple Window A/C UnitsPlanning a window unit in more than one room? How to pick the zones, size each one and run them together from the app.
310 min readJun 27th 2025
How Smart Window A/C Units Cut Energy Bills by 25%Scheduling, geofencing and setpoints that trim what a window unit costs to run once it is in.- 4
12 min readAug 8th 2025
How Smart Window Air Conditioners Are Changing Home Cooling in 2025Why renters and homes without central air are choosing smart window units, and what has changed in them.
Keep going
Not a window person?
Guides and support