The 777-300ER ("ER" for Extended Range) is the B-market version of the -300.
Its higher MTOW and increased fuel capacity permits a maximum range of 7,370 nautical miles (13,650 km) with 396 passengers in a two-class seating arrangement.
The 777-300ER features raked and extended wingtips, a strengthened fuselage and wings and a modified main landing gear.
Its wings have an aspect ratio of 9.0.
It is powered by the GE90-115B turbofan, the world's most powerful jet engine with a maximum thrust of 115,300 lbf (513 kN).

Following flight testing, aerodynamic refinements have reduced fuel burn by an additional 1.4%.

At Mach 0.839 (495 kn; 916 km/h), FL300, -59 °C and at a 513,400 lb (232.9 t) weight, it burns 17,300 lb (7.8 t) of fuel per hour.
Its operating empty weight is 371,600 lb (168.6 t).

The projected operational empty weight is 168,560 kg (371,610 lb) in airline configuration, at a weight of 216,370 kg (477,010 lb) and FL350, total fuel flow is 6,790 kg/h (14,960 lb/h) at M0.84/472 kn (874 km/h), rising to 8,890 kg (19,600 lb)/h at M0.87/506 kn (937 km/h).

Since its launch, the -300ER has been a primary driver of the twinjet's sales past the rival A330/340 series.
Its direct competitors have included the Airbus A340-600 and the A350-1000.
Using two engines produces a typical operating cost advantage of around 8–9% for the -300ER over the A340-600.
Several airlines have acquired the -300ER as a 747-400 replacement amid rising fuel prices given its 20% fuel burn advantage.
The -300ER has an operating cost of US$44 per seat hour, compared to an Airbus A380's roughly US$50 per seat hour (hourly cost is about US$26,000), and US$90 per seat hour for a Boeing 747-400 as of 2015.

The first -300ER was delivered to Air France on April 29, 2004.
The -300ER is the best-selling 777 variant, having surpassed the -200ER in orders in 2010 and deliveries in 2013.
As of July 2018, 784 -300ER aircraft were in service.
As of August 2019, -300ER deliveries to 45 different customers totalled 810, with 34 unfilled orders.
At its peak, a new 777-300ER was valued US$150 million, falling to US$17 million in 2019.
The 777-300ER ("ER" for Extended Range) is the B-market version of the -300. Its higher MTOW and increased fuel capacity permits a maximum range of 7,370 nautical miles (13,650 km) with 396 passengers in a two-class seating arrangement. The 777-300ER features raked and extended wingtips, a strengthened fuselage and wings and a modified main landing gear. Its wings have an aspect ratio of 9.0. It is powered by the GE90-115B turbofan, the world's most powerful jet engine with a maximum thrust of 115,300 lbf (513 kN).
Following flight testing, aerodynamic refinements have reduced fuel burn by an additional 1.4%.
At Mach 0.839 (495 kn; 916 km/h), FL300, -59 °C and at a 513,400 lb (232.9 t) weight, it burns 17,300 lb (7.8 t) of fuel per hour. Its operating empty weight is 371,600 lb (168.6 t).
The projected operational empty weight is 168,560 kg (371,610 lb) in airline configuration, at a weight of 216,370 kg (477,010 lb) and FL350, total fuel flow is 6,790 kg/h (14,960 lb/h) at M0.84/472 kn (874 km/h), rising to 8,890 kg (19,600 lb)/h at M0.87/506 kn (937 km/h).
Since its launch, the -300ER has been a primary driver of the twinjet's sales past the rival A330/340 series. Its direct competitors have included the Airbus A340-600 and the A350-1000. Using two engines produces a typical operating cost advantage of around 8–9% for the -300ER over the A340-600. Several airlines have acquired the -300ER as a 747-400 replacement amid rising fuel prices given its 20% fuel burn advantage. The -300ER has an operating cost of US$44 per seat hour, compared to an Airbus A380's roughly US$50 per seat hour (hourly cost is about US$26,000), and US$90 per seat hour for a Boeing 747-400 as of 2015.
The first -300ER was delivered to Air France on April 29, 2004. The -300ER is the best-selling 777 variant, having surpassed the -200ER in orders in 2010 and deliveries in 2013. As of July 2018, 784 -300ER aircraft were in service. As of August 2019, -300ER deliveries to 45 different customers totalled 810, with 34 unfilled orders. At its peak, a new 777-300ER was valued US$150 million, falling to US$17 million in 2019.
Boeing 777