The 777 Freighter (777F) is an all-cargo variant of the 777. Boeing has had some need for a large freighter to replace older 747F and MD-11F freighters. The increased payload capability of the 777-200LR has allowed the company to begin marketing a cargo derivation. The model was officially offered starting on November 15, 2004. The 777F promises excellent operating economics compared to existing freighters. The aircraft has a large interior volume and a high thrust-to-weight ratio. The large wings allow for a low wing loading. The 777F will have a payload of 101 tons. This compares favorably to that of the much larger 747-400F, which has a payload of 124 tons. With the extra belly fuel tanks sacrificed in the interest of payload, the 777F will not range as far as the passenger variant it is based upon. However, the 777F will be the longest-ranged freighter in the world with a range of 5,200 miles (8,400 km).