Quick answer: 1 inch is exactly 2.54 cm. A 55 inch TV is 139.7 cm, a 32 inch waist is 81 cm, a 28 inch bike wheel is 71 cm. The 2.54 is not a rounding: it is the international definition of the inch (NIST).
Inches follow you through every purchase: screens, jeans, bikes, phones. And the most expensive mistake is not the conversion itself, it is what the number measures.
The chart you actually need
| Inches | Centimetres | Where you meet it |
|---|---|---|
| 6.7” | 17 cm | Phone screen diagonal |
| 24” | 61 cm | Desk monitor |
| 27” | 68.6 cm | Desk monitor |
| 28” | 71 cm | Bike wheel (city bikes) |
| 30” | 76 cm | Jeans waist W30 |
| 32” | 81 cm | Jeans W32, small TV |
| 43” | 109 cm | Living-room TV |
| 55” | 140 cm | The most sold TV size |
| 65” | 165 cm | Large TV |
| 75” | 190.5 cm | Home cinema |
The TV-stand mistake
TV inches measure the diagonal of the panel, corner to corner. A 55 inch TV is 140 cm diagonally, but its width is about 122 cm (16:9 panel, before the bezel). If your TV stand is 120 cm wide, the diagonal number says it fits and reality says it does not. Always convert the diagonal, then check the width spec in cm.
Same logic for jeans: W32 means a 32 inch waistband, about 81 cm, and brands round differently. For bikes, 26, 28 and 29 inches describe the wheel, not the frame.
The maths, once and for all
Multiply inches by 2.54 to get centimetres. Divide centimetres by 2.54 to get inches. That is the whole trick: 55 × 2.54 = 139.7 cm.
A 55 inch TV: how wide is it, roughly?
TV sizes are diagonals. A 55 inch (140 cm) 16:9 panel is about 122 cm wide, plus the bezel.
In the shop aisle, one tap
Standing in front of the TV wall, type 55 into Conversion Calculator and read centimetres instantly, along with every other length unit. It handles compound sizes like 2ft6 too, the kind furniture listings love. And if that purchase flies home with you, check the 23 kg luggage trap before packing it.
Get the app free and measure before you pay.