As Air New Zealand prepares to receive the first 787-9 next week, Boeing has increased the weight and clarified the range for the two largest variants in the Dreamliner family.

Maximum take-off weight for the 787-9 and 787-10 rises to 253,000kg (557,000lb), or 1,810kg higher than previously listed.

Boeing attributes the weight growth to added range, saying the 787-9 can now fly up to 8,300nm (15,400km).

However, the company previously listed the range for the 787-9 as between 8,000-8,500nm with a lower maximum take-off weight of 251,000kg.

Boeing officials also have said that the 787-9 weight stayed below projections by “several hundred pounds” through the development process.

The 787-10 is designed to match the maximum take-off weight of the 787-9, so its specification also rose to 253,000kg, Boeing says.

Boeing also clarified the range target for the largest of the three 787 variants. The original target was listed at 7,000nm, but is now slightly higher at 7,020nm, according to a new Boeing fact sheet.

The new specifications also clarify Boeing’s listed seat counts for the three models, although actual seat counts vary significantly depending on the layout selected by each airline.

Where the 787-9 was previously described as 250-290 seats, the latest fact sheet says it is 280 seats, or 16% higher than the 242 seats on the 787-8.

Boeing also clarifies the 787-10 seat count as 323 seats instead of a range between 300 and 330.

The latest fact sheets also define the listed range of the 787-8 as 7,850nm instead of a range between 7,650 and 8,200nm.