Throw ratio
Projection distance ÷ image width. A range when the lens zooms (e.g. 1.35–2.84:1).
- Unit
- :1
- Standard
- ISO/IEC 21118 item 9, §3.6
- ISO 21118
- ISO 21118 optional
Show the numbers
| Value | Metric | Imperial |
|---|---|---|
| Image width | 2.66 m | 8′ 9″ |
| Image height | 1.49 m | 4′ 11″ |
| Nearest lens position | 3.19 m | 10′ 6″ |
| Furthest lens position | 3.98 m | 13′ 1″ |
| Room depth needed (+35 cm chassis) | 3.54 m | 11′ 7″ |
How to compare it
Throw ratio(:1)
The most important 'will it fit' spec. Compare against your room: distance = ratio × width. The range tells you your placement freedom.
Throw reference point
Where the stated distance is measured from. ISO says the outermost lens element. Anything else must be explained.
Required for UST. We render 'gap to wall from rear of unit' as a separate derived value when the depth is known.
Standard: ISO/IEC 21118 §3.6 ('other reference shall be explained')
Projection distance table(m)
Distances for specific image sizes at wide and tele zoom.
Our throw calculator uses the table when present, because it captures lens non-linearity better than the ratio alone.
Standard: ISO/IEC 21118 item 9
Image size range(in)
The diagonal sizes the manufacturer supports, i.e. what focus can achieve.
A sanity check. It says nothing about whether it's bright enough at that size; use the luminance calculator.
Standard: ISO/IEC 21118 Table 1
Illustrative unit: a 0.25:1 lens measured ISO-style, a 40 cm deep chassis, with the mirror 12 cm in from the rear. Side view, drawn to scale.
Marketing traps
- Throw ratio: ISO measures distance from the screen to the outermost lens element. UST makers often quote from the back of the chassis or from a mirror. Two '0.25:1' UST models can need very different gaps to the wall.
- Throw reference point: Failing to state the reference is the most common UST spec omission.
- Image size range: 'Up to 300″' is a focus limit, not a recommendation. At 300″, a 1,000-lumen projector puts ~13 nits (3.7 fL) on a gain-1.0 screen, about a quarter of the 48-nit cinema reference.
Across the catalogue
Throw ratio
22 of 24 projectors list it- JVC DLA-NZ81.43–2.92:1
- Epson Pro Cinema LS120001.35–2.84:1
- Sony VPL-XW7000ES1.35–2.84:1
- BenQ W58001.52–2.45:1
- Sony VPL-XW5000ES1.38–2.21:1
- XGIMI AURA 20.18:1
- Hisense PX3-PRO0.22:1
- Formovie THEATER0.23:1
- Hisense L9H TriChroma Laser TV0.25:1
- AWOL Vision LTV-3500 Pro0.25:1
Image size range
13 of 24 projectors list it- Epson Home Cinema 235040–500 in
- Optoma UHZ5034.1–302 in
- Optoma UHD35STx36.43–301 in
- Epson Pro Cinema LS1200050–300 in
- JVC DLA-NZ860–200 in
- Samsung The Freestyle 2nd Gen30–100 in
- XGIMI AURA 290–150 in
- Nebula Mars 3 Air30–150 in
- Hisense PX3-PRO80–150 in
- Formovie THEATER80–150 in
Deep cut
Throw ratio. A 16:9 image of diagonal D has width = D × 0.8716. For a 120″ 16:9 image at 1.2:1, the image is 104.6″ wide (2.66 m), so distance = 3.19 m. Throw also shifts slightly with focus distance, and some sheets quote 'at 100″'.
Projection distance table. Tables let us check the ratio. If table ÷ width differs from the stated ratio by more than ~3%, flag it for review.
Terms on this page
Ultra-short-throw (UST) / "laser TV"
Sits a few centimetres from the wall and projects upward through a steep aspect mirror. The throw ratio is roughly 0.15–0.4:1. It is almost always sold as a TV replacement with speakers, a tuner (in some regions) and a smart OS. To work in a lit room it needs an ALR screen built for UST light angles (see CLR screen). Examples: Hisense L9/PX series, Formovie Theater, AWOL Vision LTV, Samsung Premiere, Epson LS800. ⚖ category = ust, optics.throw_ratio_min
Short-throw projector
The throw ratio is roughly 0.4–1.0:1, so you get a big image from 1–2 m away. Popular for gaming and small rooms. ⚖ optics.throw_ratio_min
Throw ratio
Throw distance ÷ image width. A 1.5:1 projector, for example, needs 3 m of distance for a 2 m-wide image. Zoom lenses have a range. ⚖ optics.throw_ratio_min, optics.throw_ratio_max. This drives our throw calculator.
Throw distance
Lens-to-screen distance. ISO/IEC 21118 defines it from the screen to the outermost lens element. ⚠ For UST, manufacturers quote distance from the back of the unit or from the wall, inconsistently. We store optics.throw_distance_reference = lens | rear | front.