How to Open a Window From the Outside: Exploring Various Options

If you’re prone to forgetting or losing your house keys, knowing how to open a window from the outside could save the cost of calling out a locksmith. So, is there a way to do it?

As you can see, there are a variety of ways to open a window from the outside, but knowing the type of window you’re dealing with is crucial. So, below we’ll explain in more detail what you need to know. Let’s get started.

Check the Type of Window You Need to Open

So, let’s start with the type of window you’re trying to open from the outside. Here are the main types.

  • Casement: A casement window, which is the part of the window that opens, is attached to the window frame by hinges. The hinges can be on the side of the casement or the top or bottom. Often, with side-hinged casement windows, you have two casements making up the window. To open, you either have a lever that unlatches the casement from the frame or a crank that you wind.
  • Sash: A sash window consists of a glass panel called a sash that opens by sliding within a frame. Typically, when referring to sash windows, we’re talking about the type that slides vertically. These may be single or double-hung. With a single-hung sash, there’s only one moveable sash, whereas, in a double-hung sash, you have moveable top and bottom sashes.
  • Sliding: A sliding window is a type of sash window that slides horizontally rather than vertically.

So, those are the types of windows you’re likely to encounter. Now let’s go through how you can open each of them from the outside.

Opening Casement Windows

Prize or Push Open an Unlatched Casement Window

If your casement window operates with a lever that you push up to disengage it from the frame to open it, check the position of the lever.

A lever in a horizontal position usually means the window isn’t latched shut, even though it’s closed. If the window is secured shut, the lever is typically vertical.

So, you should be able to prize open an outward-opening casement with your fingers. An inward-opening casement can just be pushed open if it’s not latched.

If the lever is latched or the window opens and closes using a crank, opening it from the outside is a whole lot harder.

That’s because casement windows are pretty secure by design because the locking mechanisms are within the frame. So, here’s the next option.

Lever the Casement Off the Frame

The external side of an outward opening casement sits proud of the window frame. In that case, it’s possible to lever the casement away from the frame. You’ll need a crowbar to get between the casement and the frame to prize it off.

You can see how it is done in this video:

Opening Sash Windows

Push the Sash of a Sash Window Up

Turning now to sash windows, whether yours is single or double-hung, the lower sash is the one that always moves.

If you can see that the sash isn’t latched on the inside, you should be able to push the lower sash upwards using the palms of your hands.

Lever Up the Sash of a Sash Window

What if you can’t get any purchase on the window to push the sash up, for example, if the window’s wet?

You can use a crowbar wedged between the bottom of the sash and the window sill to lever the window up. Levering up the sash can break the latch, so you can do this even if the latch is engaged.

Use a Knife to Unlatch a Sash Window

Don’t have a crowbar? If your sash window is fitted with only a basic latch on top of the lower sash, you may be able to slide a knife between the two sashes to force the latch open.

Or, with some force, you may be able to break the latch if it’s not screwed down well or is only screwed into the beading.

The vulnerability of basic sash window latches is why the homeowner in this video decided to install more security on his sash window.

This way of opening a sash window from outside only works if there’s a sufficient gap between the sashes. And it assumes you have no other security on your sash windows.

Opening Sliding Windows

Jiggle a Sliding Window to Loosen the Lock

Now let’s look at how to open a sliding window from the outside.

This won’t work on all sliding windows, but if you can move the sash around in the frame, you may be able to unlatch it. You can see what we mean in the following video:

It’s worth trying this, as it’s less likely to cause damage than the next option.

Lever a Sliding Window Open

This method requires a crowbar or pry bar. You can often insert a pry bar between the sash and the frame and lever it open. This will pop or break the lock.

Skip to 53s in this video to see how. Run the video forward to 1:13, and you’ll see the same thing being done to a sliding door, which also had a locking pin at the bottom.

If All Else Fails, Cut or Break the Window Glass

Cutting or breaking the glass gives you access to the lever, latch, or crank, enabling you to open the window from the outside.

Bear in mind some crank-operated casement windows have a removable crank handle for security. So, if you peer into the window and see there’s no handle on the crank, there’s no point spending time cutting the glass to access the crank.

You’ll have the same issue on a lever-latch casement window, if it’s a lockable lever, with no key in the lock, unless you carry a key with you.

In that case, you’ll have to break the glass. So, let’s get to how to cut or break the glass in your windows.


To cut the glass, you’ll need access to the right tools, which you may or may not have.

The best tool to use is a circle glass cutter like this B BLOOMOAK Heavy Duty Circular Glass Cutter. As the name suggests, it’ll cut a circular hole in your window.

It’s great for a single-glazed pane. If you have a double-glazed window, you’d need access to the inside to use this cutter to cut the inner pane.

Or, for the inner pane, you could switch to the handheld glass cutter that comes with the circular cutter tool mentioned above.


If cutting the glass isn’t an option, then breaking the whole pane is the next possibility.

Breaking the whole pane of glass will allow you to climb through the window, assuming the casement or sash is locked. Be sure to protect your hands, face, and body from the risk of flying glass. Also, take care not to cut yourself on any remaining glass shards as you climb through.

Some of the things you can use to break the glass include the ends of crowbars, shovels, or even screwdrivers. You could also use a stone or brick and throw it at the window.

With double-glazed windows, aiming for the bottom corner is the most effective way to break the glass. This is demonstrated in the following video:

Alternatively, a useful tool you might have to hand is a center punch, like this Automatic Center Spring Loaded Center Punch. The automatic spring loading makes it easy to operate with virtually no force needed.

A center punch is usually used to make an indent in metal, so when you start drilling, your drill bit doesn’t slide around. But, it’s also effective in breaking glass.


So, if you’ve locked yourself out, whichever type of window you have, it may be possible to open it from the outside. Most involve some level of destruction, especially if you’re dealing with a locked or latched casement window.

So, if you’re trying to open a window from the outside because you’ve locked yourself out, you might find it cheaper to call a locksmith. However, be warned. Only use this information for legitimate purposes.