Singapore Airlines (SIA) customers flying to Sydney on selected flights will be the first to experience the carrier's new premium economy class from August 9, with bookings starting from Tuesday.

As the name suggests, the new product will offer more legroom, wider seats, more meal choices and better amenities compared with economy class.

Fares will differ depending on the day and time of travel but travellers can expect to pay about 15 - 20 per cent more for premium economy.

Each seat which comes with a calf-rest and foot-bar has a width ranging between 18.5 and 19.5 inches with an eight-inch recline for more ease and comfort, SIA said on Tuesday.