Projector Guide · 8 min read

Projector Throw Ratios Guide - Distance Calculations

Introduction

Choosing a projector is exciting, but many buyers overlook one critical specification: throw ratio. This single number determines whether your projector will actually fit in your room and produce the screen size you want. This comprehensive guide explains everything you need to know about throw ratios, throw distance calculations, and how to choose the right projector for your space.

What is Throw Ratio?

Throw ratio is the relationship between the projector’s distance from the screen and the width of the projected image.

The Formula

Throw Ratio = Throw Distance ÷ Image Width

Example: If your projector is 12 feet from the screen and creates a 100-inch diagonal image (87” wide for 16:9):

  • Throw Distance: 12 feet
  • Image Width: 7.25 feet (87 inches)
  • Throw Ratio: 12 ÷ 7.25 = 1.65:1

Projector Categories by Throw Ratio

Ultra Short Throw (UST)

Throw Ratio: 0.25 - 0.5 Distance for 100” Screen: 8 - 20 inches Best For:

  • Living rooms with limited space
  • Rooms where projector must be close to wall
  • Avoiding shadows from people walking

Advantages:

  • Minimal shadow interference
  • Fits in small rooms
  • Clean aesthetic (can sit on TV stand)

Disadvantages:

  • Most expensive category
  • Limited zoom/lens shift
  • Requires perfectly flat wall/screen

Popular Models: LG CineBeam, Epson LS500, VAVA 4K Laser

Short Throw

Throw Ratio: 0.5 - 1.2 Distance for 100” Screen: 3 - 8 feet Best For:

  • Small to medium home theaters
  • Bedrooms
  • Apartments

Advantages:

  • Good balance of price and flexibility
  • Less shadow interference than standard
  • Easier setup than UST

Disadvantages:

  • Still more expensive than standard
  • Requires some wall clearance

Popular Models: BenQ HT2050A, Optoma GT1080HDR

Standard Throw

Throw Ratio: 1.2 - 2.0 Distance for 100” Screen: 8 - 16 feet Best For:

  • Dedicated home theaters
  • Medium to large living rooms
  • Ceiling mount installations

Advantages:

  • Most affordable
  • Widest selection of models
  • Best image quality per dollar
  • Often includes zoom and lens shift

Disadvantages:

  • Requires mounting distance
  • Shadows from people walking
  • Cable management needed

Popular Models: Epson Home Cinema 2250, BenQ HT3550, Sony VPL-VW295ES

Long Throw

Throw Ratio: 2.0 - 5.0+ Distance for 100” Screen: 16 - 40+ feet Best For:

  • Large venues
  • Auditoriums
  • Commercial installations
  • Rear projection setups

Advantages:

  • Massive screen sizes possible
  • Professional image quality
  • Advanced features

Disadvantages:

  • Requires large room
  • Professional installation recommended
  • Expensive

How to Calculate Throw Distance

Method 1: Using Throw Ratio

If you know the desired screen size:

  1. Find your screen width (not diagonal)
  2. Multiply by the throw ratio

Example: 120” diagonal 16:9 screen (width = 104.6”)

  • Projector throw ratio: 1.5:1
  • Throw distance = 104.6” × 1.5 = 157 inches (13.1 feet)

Method 2: Using Our Calculator

Want an instant answer? Use our Projector Calculator (switch to Projector mode):

  1. Enter desired screen size
  2. Select throw ratio from dropdown
  3. Get exact throw distance and minimum wall width

Throw Ratio Quick Reference Table

Screen SizeUltra Short (0.4)Short Throw (0.8)Standard (1.5)Long Throw (2.0)
80” (70” wide)28” (2.3 ft)56” (4.7 ft)105” (8.8 ft)140” (11.7 ft)
100” (87” wide)35” (2.9 ft)70” (5.8 ft)131” (10.9 ft)174” (14.5 ft)
120” (105” wide)42” (3.5 ft)84” (7.0 ft)158” (13.1 ft)210” (17.5 ft)
150” (131” wide)52” (4.4 ft)105” (8.7 ft)197” (16.4 ft)262” (21.8 ft)
200” (174” wide)70” (5.8 ft)140” (11.6 ft)261” (21.8 ft)348” (29 ft)

Zoom Range and Flexibility

Many projectors don’t have a single fixed throw ratio - they have a zoom range.

Example: Epson Home Cinema 5050UB

  • Throw Ratio Range: 1.35 - 2.84:1
  • For 100” screen (87” wide):
    • Minimum distance: 87” × 1.35 = 118” (9.8 ft)
    • Maximum distance: 87” × 2.84 = 247” (20.6 ft)

This flexibility lets you adjust screen size without moving the projector.

Lens Shift vs Digital Keystone

Lens Shift (Optical)

Vertical: ±60% or more Horizontal: ±24% or more

Advantages:

  • No image quality loss
  • Maintains full resolution
  • Professional result

How it works: Physical lens movement

Digital Keystone

Range: Varies (usually ±30°)

Disadvantages:

  • Reduces effective resolution
  • Can introduce artifacts
  • Should be avoided if possible

When to use: Only as last resort

Room Planning Guide

Step 1: Measure Your Room

Measure:

  • Wall width for screen
  • Distance from projector location to screen
  • Ceiling height
  • Seating distance from screen

Step 2: Determine Screen Size

Based on seating distance:

  • Optimal viewing: Screen width = Viewing distance ÷ 2
  • Example: 12 feet seating distance = 72” screen width ≈ 84” diagonal (16:9)

Step 3: Calculate Required Throw Distance

Use formula: Screen Width × Throw Ratio

Step 4: Check if Projector Fits

Ceiling mount:

  • Distance fits between ceiling mount location and screen
  • Enough ceiling height for lens shift
  • Cable routing possible

Table mount:

  • Table can be placed at calculated distance
  • Height allows proper projection angle
  • Ventilation space available

Common Mistakes to Avoid

1. Ignoring Throw Ratio

Problem: Buying projector before checking if it fits room Solution: Always calculate throw distance first

2. Relying Only on Digital Keystone

Problem: Poor image quality from digital correction Solution: Use optical lens shift or proper mounting

3. Forgetting About Zoom Limits

Problem: Assuming infinite adjustability Solution: Check manufacturer’s throw distance calculator

4. Not Accounting for Screen Border

Problem: Image extends past screen edges Solution: Add 2-3 inches margin when measuring

5. Ceiling Height Issues

Problem: Can’t mount high enough for proper angle Solution: Choose short throw or check lens shift specs

Throw Ratio by Use Case

Small Apartment (10x12 ft room)

Recommended: Ultra Short Throw (0.25-0.5)

  • 100” screen from just 8-20 inches
  • Sits on TV stand
  • No mounting needed

Medium Living Room (15x18 ft)

Recommended: Short Throw (0.8-1.2)

  • 100” screen from 5-8 feet
  • Flexible placement
  • Good value

Dedicated Home Theater (20x25 ft)

Recommended: Standard Throw (1.5-1.8)

  • Best image quality
  • Professional installation
  • Most features for price

Large Basement Theater (25+ ft)

Recommended: Standard to Long Throw (1.5-2.5)

  • Massive screen sizes (150-200”+)
  • Ceiling mount at rear
  • Cinema experience

Advanced Considerations

Aspect Ratio Impact

Throw ratio measures width, so aspect ratio matters:

100” diagonal screen:

  • 16:9: 87.2” wide
  • 2.35:1 (Cinema): 93.2” wide
  • 4:3: 80” wide

Same projector, different distances needed for same diagonal size!

Anamorphic Lenses

For 2.35:1 screens:

  • Use with 16:9 projector
  • Squeeze image horizontally
  • Effectively changes throw ratio
  • Professional feature

Vertical Offset

Most projectors project above the lens center:

  • Typical offset: 5-15% of image height
  • Check specs for exact percentage
  • Affects mounting height calculation

Throw Distance Calculator Tools

Manufacturer Calculators

Most brands provide online calculators:

  • Epson Projector Calculator
  • BenQ Projector Selector
  • Sony Projection Distance Tool

Our Universal Calculator

Use our Projector Calculator for any projector:

  1. Switch to Projector mode
  2. Enter screen size
  3. Select throw ratio (or enter custom)
  4. Get instant throw distance + wall width

Real-World Examples

Example 1: Small Living Room

  • Room: 12 ft ceiling to screen wall
  • Goal: 100” screen
  • Solution: Short throw projector (0.8 ratio)
    • Distance needed: 5.8 feet
    • Mount: Coffee table or low shelf
    • Perfect fit ✓

Example 2: Dedicated Theater

  • Room: 22 ft deep
  • Goal: 135” screen
  • Solution: Standard throw (1.5 ratio)
    • Distance needed: 14 feet
    • Mount: Ceiling mount at 15 ft from screen
    • Includes 1 ft adjustment room ✓

Example 3: Won’t Work

  • Room: 8 ft ceiling to screen
  • Goal: 120” screen
  • Projector: Standard throw (1.5 ratio)
    • Distance needed: 13.1 feet
    • Problem: Room only 8 feet deep ✗
    • Solution: Switch to short throw (0.8) = 7 ft ✓

Buying Checklist

Before purchasing a projector:

  • ✅ Measured wall-to-mounting-location distance
  • ✅ Decided on screen size
  • ✅ Calculated required throw ratio
  • ✅ Confirmed projector specs match room
  • ✅ Checked zoom range for flexibility
  • ✅ Verified lens shift capabilities
  • ✅ Planned cable routing
  • ✅ Confirmed ceiling/mount compatibility
  • ✅ Considered ambient light (brightness needs)
  • ✅ Checked resolution matches content (4K vs 1080p)

Conclusion

Understanding throw ratio is essential for projector success. The formula is simple: Throw Distance = Screen Width × Throw Ratio.

Quick Rules:

  • Small rooms (< 12 ft): Ultra short throw (0.25-0.5)
  • Medium rooms (12-18 ft): Short throw (0.8-1.2)
  • Large rooms (18+ ft): Standard throw (1.5-2.0)

Pro Tip: When between two options, choose the projector with a zoom range that puts your desired distance in the middle of its range, not at the extreme ends.

Ready to calculate your exact throw distance? Use our free Projector Throw Calculator with instant distance calculations and wall width requirements.