Flight route
London to Delhi
4,183 miles - roughly 9.25 hours in the air. You'll fly into DEL.
So - is the upgrade worth it on this one?
Honestly? This is exactly the length of route where it stops being a small treat. At 9.25 hours each way, the seat stops being a chair and starts being where you sleep - and the gap between a flat bed and an upright night is the gap between arriving ready and arriving ruined. Premium economy often hits the sweet spot on price; business is the one you'll remember. The right answer still depends on the fare difference on your exact dates, which changes daily.
Ask Aster with your dates and it compares live fares in economy, premium economy, business and first side by side - including what the seat itself is actually like - and gives you a straight answer instead of a hunch.
What the seat is actually like
Most flight sites sell you a cabin name. Aster keeps a seat-intelligence library of real aircraft layouts across 25 carriers - so on this route it can tell you whether "business" means a private suite with a door or an older recliner, before you spend the difference. That distinction matters more on Delhi than almost any other factor.