Tell it how far you sit, how big your room is and what kind of projector you have. It works out the screen size from the SMPTE and THX viewing standards, where the projector goes (the throw distance), how many lumens the picture needs, and shows it all to scale in 3D, with projectors that can do it.
From 10 ft away · Movies & gaming
Get a 100-inch screen
A 100″ fills 40° of your view; THX recommends about 40°. Also just right: 90″, 106″, 110″.
Put the projector’s lens 8 ft 9 in to 14 ft 6 in from the screen, about level with your seat: a ceiling mount above you, or a shelf just behind. It needs about 900 lumens for a dim room.
Your viewing angleThe projector’s light
Try a size
100″: Just rightfills 40° of your view
What you watch most
THX: the screen fills about 40° of your view.
Projector type
Most home theater projectors, with a zoom lens: on a ceiling mount or a shelf behind you. A typical range, 1.2 to 2.0:1.
Room light
Lights low or curtains drawn. 30 fL is our rule-of-thumb target.
Sizes are the 16:9 picture; a framed screen is bigger on the outside. The lens spot is the middle of the range your room allows, and ignores lens shift: check your projector’s manual. Lumens are for a white screen with gain 1.0.
Checked against your room (18 ft long): can the lens sit 8 ft 9 in to 14 ft 6 in from the screen, and is it bright enough for a dim room?
Best Overall
Best for living-room and basement theaters
Also worth a look
Best Smart Value
Valerion StreamMaster Plus2
Best for streaming and gaming in one box
Best Color
Valerion VisionMaster Pro2
Best for cinephiles who want laser color and smart features
Most Flexible Setup
Hisense C2 Ultra
Best for rooms without a fixed screen spot
Best Dedicated Theater
Epson Home Cinema LS11000
Best for dark home theater rooms
Need something small and portable? See our Portable projectors.
From each maker’s spec sheet, or ProjectorCentral and Projector Point where the maker doesn’t publish the number. ANSI and ISO lumens can be compared with each other. Makers quote the brightest mode.
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The exact diagonal that fills each standard’s viewing angle from your seat, and the closest 16:9 screen size sold. Under 60 inches a TV is simpler: see our TV size calculator. Past 150 inches, check your wall and ceiling first.
| Seat to screen | Everyday viewing (SMPTE 30°) | Movies & gaming (THX 40°) |
|---|---|---|
| 6 ft (1.83 m) | 60″ (exact 44″) or a TV | 60″ (exact 60″) |
| 7 ft (2.13 m) | 60″ (exact 52″) | 70″ (exact 70″) |
| 8 ft (2.44 m) | 60″ (exact 59″) | 80″ (exact 80″) |
| 9 ft (2.74 m) | 70″ (exact 66″) | 90″ (exact 90″) |
| 10 ft (3.05 m) | 70″ (exact 74″) | 100″ (exact 100″) |
| 11 ft (3.35 m) | 80″ (exact 81″) | 110″ (exact 110″) |
| 12 ft (3.66 m) | 90″ (exact 89″) | 120″ (exact 120″) |
| 13 ft (3.96 m) | 100″ (exact 96″) | 135″ (exact 130″) |
| 14 ft (4.27 m) | 106″ (exact 103″) | 135″ (exact 140″) |
| 15 ft (4.57 m) | 110″ (exact 111″) | 150″ (exact 150″) |
| 16 ft (4.88 m) | 120″ (exact 118″) | 150″ (exact 160″) or bigger |
How far the lens sits from the screen: throw ratio × picture width. 1.2:1 and 1.5:1 are two common ratios; your projector’s spec sheet gives its own, and a zoom lens covers a range. Lumens are for a plain white screen (gain 1.0): 16 fL for a dark room, 30 fL for a dim room.
| Screen size | Picture (wide × tall) | Throw at 1.2:1 | Throw at 1.5:1 | Lumens, dark room (16 fL) | Lumens, dim room (30 fL) |
|---|---|---|---|---|---|
| 80″ | 70 × 39 in (177 × 100 cm) | 7 ft (2.13 m) | 8 ft 9 in (2.66 m) | 300 | 550 |
| 90″ | 78 × 44 in (199 × 112 cm) | 7 ft 10 in (2.39 m) | 9 ft 10 in (2.99 m) | 400 | 700 |
| 100″ | 87 × 49 in (221 × 125 cm) | 8 ft 9 in (2.66 m) | 10 ft 11 in (3.32 m) | 450 | 900 |
| 106″ | 92 × 52 in (235 × 132 cm) | 9 ft 3 in (2.82 m) | 11 ft 7 in (3.52 m) | 550 | 1,000 |
| 110″ | 96 × 54 in (244 × 137 cm) | 9 ft 7 in (2.92 m) | 12 ft (3.65 m) | 550 | 1,100 |
| 120″ | 105 × 59 in (266 × 149 cm) | 10 ft 6 in (3.19 m) | 13 ft 1 in (3.98 m) | 700 | 1,300 |
| 135″ | 118 × 66 in (299 × 168 cm) | 11 ft 9 in (3.59 m) | 14 ft 8 in (4.48 m) | 850 | 1,600 |
| 150″ | 131 × 74 in (332 × 187 cm) | 13 ft 1 in (3.98 m) | 16 ft 4 in (4.98 m) | 1,050 | 2,000 |
Viewing angle, not guesswork. A screen looks big or small depending on how much of your view it fills. SMPTE, the body that sets film and TV engineering standards, recommends at least 30° side to side; THX recommends about 40° for a cinema feel. This is the same maths as our TV size calculator: it finds the picture width that fills that angle from your seat, turns it into a 16:9 diagonal, and picks the closest size screens are sold in. Sizes are the picture itself; a fixed-frame screen is bigger on the outside, so check the listing’s full dimensions. Tap m to work in metres and centimetres.
Your wall, ceiling and eye line. The screen can’t be wider than your wall minus 6 in of clear wall on each side, or taller than the space between the floor and ceiling: the bottom edge stays at least 24 in off the floor and the top at least 4 in under the ceiling. The calculator puts the lower third of the picture at your seated eye height (40 in), so you look slightly up at the middle of the picture, the way you do in a cinema. On an 8 ft ceiling that tops out at a 135-inch screen.
Throw distance. A projector’s throw ratio is the distance from its lens to the screen divided by the picture width, so throw distance = throw ratio × picture width. A zoom lens has a range of ratios, and so a range of places it can sit. The four types in the calculator use typical ranges (ultra short throw 0.2 to 0.4:1, short throw 0.4 to 1.0:1, standard 1.2 to 2.0:1, long throw 2.0 to 3.0:1). They are rules of thumb, not standards: every model has its own, on its spec sheet. For “one of our projectors” we use the throw ratios from each maker’s spec sheet (ProjectorCentral or Projector Point where the maker doesn’t publish it), checked on 3 November 2026. The lens has to sit inside your room, at least 12 in from the back wall, and the calculator tells you whether that spot is in front of your seat (a coffee table or shelf), above or behind it (a ceiling mount or a shelf), or at the wall (ultra short throw). It doesn’t model lens shift, so check your projector’s manual for how far up or down the lens can sit.
Brightness. Lumens needed = picture area in square feet × foot-lamberts ÷ screen gain. We use a plain white screen (gain 1.0). 16 foot-lamberts (fL) is the SMPTE cinema reference for a dark room. 30 fL for a dim room and 50 fL for a bright living room are our rule-of-thumb targets, not standards. Each projector’s published figure is compared with that number. ANSI and ISO lumens are measured the same way, so you can compare them; a bare “lumens” on a listing is not a standard measure and can be inflated. Makers quote the brightest mode, and movie modes are dimmer, so leave some headroom.
What it can’t know. Your room’s wall colour and reflections, screen gain beyond 1.0, ambient-light-rejecting screens, keystone correction and lens shift on your exact projector. Measure the distance from your eyes, not the front of the sofa, and check the model’s throw table before you drill any holes.
By Jamilur Rahman. Prices on this page are from our guides and change on Amazon; we earn from qualifying purchases.
Multiply your seat distance by about 0.6 for everyday viewing (SMPTE, 30°) or about 0.8 for a cinema feel (THX, 40°). From 10 ft (120 in) that is about 74 inches or 100 inches. Then check the wall (the screen plus 6 in each side must fit) and the ceiling (an 8 ft ceiling tops out at 135 inches). For a home theater, most people go for the cinema number.
A 100-inch screen for movies: from 10 ft it fills 40° of your view, the THX cinema target. For everyday TV and sports, SMPTE’s 30° works out to about 74 inches, so a 70-inch (29°) or 80-inch (32°) screen. A 120-inch screen from 10 ft fills 47°, which is a lot.
Measure from your pillow to the wall. Most beds put you 6 to 9 ft away, which for a cinema feel is 60 inches at 6 ft, 70 at 7 ft, 80 at 8 ft and 90 at 9 ft (each fills 40° of your view). For everyday viewing a 60-inch screen from 8 ft fills about 30°. Bedrooms are short, so check the throw: for an 80-inch screen a 1.2 to 2.0:1 projector sits 7 ft to 11 ft 7 in from it.
It depends on the throw ratio. A 100-inch 16:9 screen is 87 inches wide, so a projector with a 1.2:1 lens sits 8 ft 9 in from the screen, a 1.5:1 lens 10 ft 11 in, and a 2.0:1 lens 14 ft 6 in. An ultra short throw projector (about 0.2 to 0.4:1) sits just 17 in to 2 ft 11 in from the screen. Measure from the lens to the screen.
A 120-inch screen is 105 inches wide, so a 1.2:1 projector sits 10 ft 6 in from the screen and a 1.5:1 one 13 ft 1 in. A projector with a zoom lens of 1.2 to 2.0:1 can go anywhere from 10 ft 6 in to 17 ft 5 in. An ultra short throw projector sits about 21 in to 3 ft 6 in from it. Put your numbers in the calculator to see if the spot fits your room.
Throw distance = throw ratio × picture width, and the width of a 16:9 picture is 0.872 × the diagonal. For a 100-inch screen at 1.5:1 that is 1.5 × 87.2 in = 130.7 in, or 10 ft 11 in. Turn it around to find the screen from the projector: width = distance ÷ ratio. A projector with a 1.2 to 1.5:1 zoom lens 10 ft from the screen fills a picture of 92 to 115 inches.
It is how far the projector sits from the screen compared with how wide the picture is. A 1.5:1 ratio means 1.5 ft of distance for every 1 ft of picture width. A lower ratio means a closer projector. A single number (the Valerion StreamMaster Plus2’s 1.2:1) is a fixed lens; a range (the Epson Home Cinema 3800’s 1.32 to 2.15:1, or the Hisense C2 Ultra’s 0.9 to 1.5:1) is a zoom lens that gives you room to place it. Look for it on the spec sheet.
It depends on the screen size and the room’s light. A 100-inch screen (29.7 sq ft) needs about 450 lumens in a dark room (16 fL), 900 in a dim room (30 fL) and 1,500 with the lights on (50 fL). A 120-inch screen needs about 700, 1,300 and 2,150. A 3,000-lumen projector covers a 120-inch screen even in a bright room; a 500-lumen portable one covers a 100-inch screen only in a dark room.
It depends on where you sit. A 100-inch screen fills 40° of your view from 10 ft and 30° from 13 ft 7 in. A 120-inch fills 40° from 12 ft and 30° from 16 ft 3 in. So 100 inches suits seats 10 to 13 ft away and 120 inches suits 12 to 16 ft. The bigger screen needs 44% more light (42.7 sq ft against 29.7), a wall at least 9 ft 9 in wide (against 8 ft 3 in), and puts the projector about 21 in further back at 1.2:1.