TV Size & Optimal Viewing Distance Calculator

Calculate the perfect TV diagonal screen size (inches/cm) for your living room viewing distance based on THX & SMPTE cinema guidelines.

Which TV size for your living room, from your sofa distance

The tool divides the sofa-to-screen distance by 0.0315 m for a cinema experience and by 0.042 m for everyday viewing, which gives the diagonal in inches. At 2.8 m it suggests 89 inches in cinema mode and 67 inches in standard mode, within a 60 to 98-inch range.

Two ways to calculate

  • I know my distance: cinema diagonal = distance ÷ 0.0315; standard diagonal = distance ÷ 0.042 (in inches, rounded). The range shown runs from 90% of the standard diagonal to 110% of the cinema diagonal.
  • I know my TV (24 to 120 inches): cinema distance = diagonal × 0.0315 m; standard distance = diagonal × 0.042 m.
  • 16:9 dimensions: width = diagonal in cm × 0.8715, height = diagonal in cm × 0.4903. The width is used as the minimum width of the TV stand.

Example

Your sofa is 2.8 m from the screen. 2.8 ÷ 0.0315 = 88.9, so 89 inches in cinema mode; 2.8 ÷ 0.042 = 66.7, so 67 inches in standard mode. The range is 60 to 98 inches. An 89-inch TV (226 cm diagonal) measures 197 × 111 cm and needs a stand wider than 197 cm. The other way round, a 65-inch TV is watched from 2.0 m in cinema mode and 2.7 m in standard mode.

Where the coefficients come from

They are guidelines. THX suggests multiplying the distance in inches by 0.835 to get the diagonal, which gives 92 inches at 2.8 m: the tool's coefficient (0.0315) is slightly more conservative. Standard mode uses a field of view of about 30°, taken from an SMPTE guide for cinema theatres withdrawn in 2003. The resolution you select (1080p, 4K, 8K) does not change the displayed results. The mounting-height tip is indicative. For pixel density, ultrawide screens or monitors, the screen size, PPI and viewing distance calculator goes further.

Sources and dates: THX, "What size TV should I buy for my living room?" (distance × 0.835, article dated 28/05/2020); SMPTE EG 18-1994, Design of Effective Cine Theaters (about 30° of the horizontal field; withdrawn 26/03/2003) (checked 14/10/2026)

Frequently Asked Questions

What TV size for a 3-metre viewing distance?

At 3 m the tool suggests 95 inches in cinema mode (3 ÷ 0.0315) and 71 inches in standard mode (3 ÷ 0.042). THX's rule, distance in inches × 0.835, gives 99 inches.

How far should I sit from a 55-inch TV?

The tool gives 1.7 m in cinema mode (55 × 0.0315) and 2.3 m in standard mode (55 × 0.042). The THX rule (diagonal ÷ 0.835) puts the sofa at 1.67 m.

How wide a TV stand do I need for a 75-inch TV?

A 75-inch 16:9 TV is about 166 cm wide (190.5 cm diagonal × 0.8715) and 93 cm high. Plan for a stand of at least 166 cm, or wider if the feet sit at the edges.

Should a 4K TV be bigger than a Full HD one?

4K pixels are half the width of 1080p pixels on a TV of the same size, so you can sit closer without seeing them. In this tool, the resolution setting does not change the suggested size, which is based only on viewing angle.

Is this tool really free?

Yes, all tools on Kristools are 100% free and accessible without registration.

Is my data protected?

Yes. All processing is performed directly and securely inside your browser. No personal data is sent to our servers.