Projector Throw Calculator

Calculate projector throw distance, screen size, and throw ratio for perfect home cinema and presentation setup

Calculate Your Projector Setup

What would you like to calculate?

Screen Size (diagonal)

Throw Distance

Throw Ratio

Screen Aspect Ratio

How Projector Throw Works

The throw distance is the measurement from your projector lens to the screen surface. This distance directly affects the size of the projected image.

Throw Ratio = Throw Distance ÷ Image Width

Key Concepts

Throw Ratio: A numerical value that tells you how far the projector needs to be from the screen relative to the image width. For example, a 1.5:1 throw ratio means the projector should be 1.5 metres away for every metre of screen width.

Image Width: The horizontal measurement of the projected image, calculated from the diagonal screen size and aspect ratio.

Example: With a 100-inch screen (16:9 aspect ratio) and a 1.2:1 throw ratio, the projector should be positioned approximately 2.6 metres from the screen.

Types of Projector Throw

Standard Throw (1.5:1 to 3.0:1)

Most common type for home cinemas and meeting rooms. Requires moderate distance and offers flexibility in room layout.

Short Throw (0.4:1 to 1.5:1)

Ideal for smaller rooms or wall-mounted installations. Reduces shadows and glare whilst producing large images from close distances.

Ultra-Short Throw (Less than 0.4:1)

Perfect for tight spaces. Can project a 100-inch image from just 20-50cm away. Often used in classrooms and small living rooms.

Top Tip: Consider your room size, furniture placement, and ceiling height when choosing a throw ratio. Short throw projectors reduce the risk of casting shadows on the screen.

Setup Planning Guide

Room Measurement

Measure the distance from where you plan to mount the projector to the wall where the screen will be placed. Consider obstacles like furniture, ceiling fans, or light fixtures.

Screen Placement

Position your screen at an appropriate height for comfortable viewing. The centre of the screen should be at eye level when seated.

Projector Mounting

Account for lens shift capabilities and keystone correction when determining the exact mounting position. Most projectors offer some adjustment range.

Important: Always check your specific projector model’s specifications, as throw ratios can vary even within the same brand and series.

Common Calculations

Finding Throw Distance

Distance = Throw Ratio × Screen Width

Finding Screen Size

Screen Width = Distance ÷ Throw Ratio

Finding Throw Ratio

Throw Ratio = Distance ÷ Screen Width

Practical Example: You have 4 metres of space and want to know what screen size you can achieve with a 1.8:1 throw ratio projector. Calculation: 4m ÷ 1.8 = 2.22m screen width, which equals approximately a 120-inch diagonal screen (16:9 aspect ratio).

Frequently Asked Questions

What is the ideal throw ratio for home cinema?

For most home cinema setups, a throw ratio between 1.2:1 and 2.0:1 works well. This range allows for flexible room layouts whilst maintaining good image quality. Consider your room size and seating arrangement when choosing.

How accurate are throw distance calculations?

Calculations provide a good starting point with typical accuracy of ±5%. However, individual projector models may have slight variations in their optics. Always consult your projector’s manual for exact specifications and test the setup before final installation.

Can I mount a projector off-centre from the screen?

Yes, many projectors offer lens shift and keystone correction features that allow off-centre mounting. However, for the best image quality, centre mounting is recommended. Check your projector’s lens shift range before planning an offset installation.

What’s the difference between throw distance and projection distance?

These terms are often used interchangeably and both refer to the distance from the projector lens to the screen surface. Some manufacturers may specify additional clearance requirements around the projector for proper ventilation.

How do zoom lenses affect throw calculations?

Projectors with zoom lenses have a range of throw ratios (e.g., 1.5-2.0:1). This means you can adjust the image size without moving the projector. The zoom range gives you flexibility in positioning whilst maintaining your desired screen size.

What factors affect the final image size?

The main factors are throw distance, throw ratio, and zoom setting (if available). Environmental factors like room temperature can cause minor variations. Lens shift adjustments change image position but not size.