Bengala
How to project on a window for Halloween
Published October 8, 2026
Short answer. Put the projector inside the house, 1 to 3 meters (3 to 10 feet) behind the window. Hang something white and translucent on the glass: frosted film, a sheer curtain or a shower liner. Flip the picture with mirror output, turn off the room lights, and aim a dark effect at the pane. A projector rated at 300 ANSI lumens or more works. Plain glass does not.
A window is the best first surface for Halloween. It has four corners, anyone on the street can see it, and it is dark behind the glass. The only trick is that glass lets light pass through, so you need something for the light to land on.
Why plain glass fails
Shine a projector at a clean window and most of the light goes straight through into the yard. People outside see a faint smear. You also see your own reflection. The picture needs a surface that catches the light and glows from the other side. That is rear projection: the projector is behind the surface, and the audience is in front of it.
What you need
- A projector with an HDMI input, or one that supports AirPlay. See the cheap projector guide if you are still shopping.
- An iPhone or iPad, and a USB-C or Lightning to HDMI adapter with an HDMI cable.
- Something translucent for the glass (options below).
- Tape, a tension rod or suction hooks to hold it flat.
- A table, shelf or tripod for the projector, and an extension cord.
- A dark room. Close the door, turn off the lamps, shut the blinds on the other windows.
Pick the layer on the glass
| Layer | What you get | The catch |
|---|---|---|
| Frosted window film | The sharpest, brightest picture | Static-cling film comes off, adhesive film may not |
| Sheer white curtain | Quick and cheap, soft picture | Folds show, and the picture is a little blurry |
| White shower liner | Even glow, easy to hang | Wrinkles catch the light, and it can sag |
| Bedsheet | Always on hand | Dimmer, because it soaks up light |
| Rear projection film | The best picture | The most expensive, and made for a permanent setup |
For one night, a shower liner or a sheer curtain is enough. If you plan to do this every year, frosted film is worth it.
Set it up in six steps
- Hang the layer flat. Tape it at the top and sides so it hangs without folds, as close to the glass as you can. Gaps and wrinkles show up as bright lines.
- Place the projector. Put it 1 to 3 meters (3 to 10 feet) behind the window, level with the middle of the pane and roughly centered. Closer gives a smaller, brighter picture. Further gives a bigger, dimmer one.
- Connect the phone. Plug the adapter into the phone and the HDMI cable into the projector. Pick the right HDMI input on the projector. Bengala shows the connected projector at the top of the home screen.
- Turn on mirror output. From behind the surface, the picture comes out flipped. In the editor menu, switch on Mirror output so it reads correctly for people outside. Text is the easy way to check.
- Draw the shape. Add a shape and drag its four corners to the four corners of the pane. The picture bends to fit, so you do not have to place the projector perfectly. Turn off keystone correction on the projector itself, because it softens the picture.
- Pick an effect and kill the lights. Choose something from the Halloween theme and walk outside to look at it.
What looks good on a window
Black is not light. Whatever is black in an effect adds nothing to the glass, so the window stays dark where the effect is dark. That is why eyes in the dark, a face behind the curtain or a figure walking past work so well. A bright, full-frame color wash turns the window into a lamp and loses the spooky part.
Keep the motion slow. A creature that takes ten seconds to cross the window is scarier than one that flashes by.
Fix the common problems
- The picture is dim. Move the projector closer, make the shape smaller, switch off every other light, or swap a thick layer like a bedsheet for a thinner one. A 300 lumen projector is the floor for a window at night. A streetlight right outside can wash it out.
- There is one bright spot in the middle. Thin layers show the bulb. Move the projector back a little, or use a thicker layer.
- The picture is backwards. Mirror output is off. Turn it on.
- A faint gray rectangle shows around the shape. No projector makes true black, so the whole beam glows a little. Move the projector back until the beam is only a bit bigger than the pane, lower its brightness, and hang black card or cloth around the edges of the pane to catch the glow.
- It lags when you drag a corner. You are on AirPlay. Plug in with HDMI. See AirPlay vs HDMI.
Stay safe
Projectors get hot and need air. Keep the vents clear and keep curtains, sheets and paper decorations away from the exhaust side. Do not leave it running unattended overnight. Tape down cables where people walk.
Some effects flash or change brightness quickly. If anyone nearby has photosensitive epilepsy, stick to slow effects. Do not aim the projector into neighbors’ windows or at passing cars.
More ideas
Once the window works, try the front door, a hedge or a pumpkin on the porch. The Halloween house projection ideas guide has setups for each. New to the whole thing? Start with the beginner’s guide.