THX & SMPTE Standards - 2026

40 Inch TV Viewing Distance

Ideal viewing distance for a 40 inch 4K TV: 1.5-2.1 m (5-7 ft) by THX. Best for: bedroom or small kitchen. Table, dimensions and calculator.

THX & SMPTE4K & Full HDMeters & Feet

Quick reference - 40 inch

4K Minimum

1.5 m

4.9 ft

Recommended (THX)

1.5-2.1 m

5-7 ft

Maximum

2.3 m

7.4 ft

Quick answer

The ideal viewing distance for a 40 inch 4K TV is 1.5 to 2.3 m (4.9-7.4 ft). For Full HD 1080p: sit 1.7 to 2.6 m from the screen. Based on THX and SMPTE professional standards.

Distance guide

Ideal viewing distance for a 40 inch TV

A 40 inch TV fits perfectly in a bedroom at 1.5-2 meters viewing distance. At 2 meters it delivers a relaxed 25 degree viewing angle. For a living room, 40 inches is on the small side - consider 50 or 55 inches.

Resolution	Minimum	Recommended (THX)	Maximum (SMPTE)
4K Ultra HD	1.5 m (4.9 ft)	1.5-2.1 m (5-7 ft)	2.3 m (7.4 ft)
Full HD 1080p	1.7 m (5.6 ft)	2.1 m	2.6 m (8.5 ft)

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4K advantage: 13% shorter minimum distance than Full HD. 40 inch 4K: 110 PPI vs 62 PPI for HD.

Dimensions & Use case

40 inch TV: dimensions and compatibility

Screen width

89 cm

Screen height

50 cm

4K PPI

110

HD PPI

⚙

Comparison: 55 inches has almost twice the picture area and works in any living room.

THX, SMPTE and ITU-R explained

THX (36 degrees): screen width 89 cm / tan(18 degrees = 0.3249) = 2.7 m = recommended distance 1.5-2.1 m. SMPTE (30 degrees) gives maximum 2.3 m. ITU-R BT.2022 (1.5x screen height) gives minimum 0.8 m.

Calculator

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Distance check for 40 inch

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FAQ

Questions about the 40 inch viewing distance

For 4K, THX recommends 1.5-2.1 m (5-7 ft) - the 36 degree angle for maximum immersion. For Full HD, the minimum distance is 1.7 m. Rule of thumb: distance in cm divided by 167 gives the ideal screen size in inches.

4K (110 PPI) allows sitting 13% closer than Full HD (62 PPI). In practice: 4K minimum 1.5 m, Full HD minimum 1.7 m. At short viewing distances 4K is a necessity, not a luxury.

Screen width 89 cm, height 50 cm (picture area only). With bezel: 92-95 cm wide, 54-58 cm tall. Diagonal 40 inches = 102 cm.

Formula: screen width (89 cm) divided by tan(18 degrees = 0.3249) = 2.7 m. That is the distance where the screen occupies 36 degrees of your field of view. SMPTE (30 degrees): 89 / 0.2679 = 3.3 m = maximum 2.3 m.

From the front edge of your sofa or chair to the wall where the TV will go. Not the room length. If the TV sits on a cabinet, measure to the front edge of the cabinet.

You can, but beyond 2.3 m you lose picture density and fine detail. If you want to sit further back, choose a larger TV.

Not sure which size is right?

Our calculator finds the ideal TV size for any distance and resolution.

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Other sizes

Viewing distance for other TV sizes

32 inch 43 inch 50 inch 55 inch 60 inch 65 inch 70 inch 75 inch 77 inch 80 inch 85 inch 98 inch 100 inch