(Recasts with comparison to analyst forecast, cost outlook, other metrics)

Oct 28 (Reuters) - Newmont Mining Corp, the biggest U.S.-based gold miner, reported lower earnings on Wednesday but the results were better than the market expected on the back higher gold production and lower cost.

Denver-based Newmont also improved its cost outlook for the year and announced it would expand its Tanami gold mine in Australia.

Newmont said its net income from continuing operations was $202 million, or 38 cents a share, in the quarter ended September 30, from $210 million, or a 42 cents a share, in the same period a year ago.

Adjusted net income was $126 million, or 23 cents a share, ahead of analysts expectations of 17 cents, on average, according to Thomson Reuters I/B/E/S.

Newmont lowered its forecast for all-in sustaining costs this year to between $880 and $940 an ounce. Its previous forecast was for costs of between $920 and $980 in 2015.

It left its 2015 production forecast of 4.7 million ounces to 5.1 million ounces unchanged.

In the third quarter, attributable gold production from Newmont mines in the Americas, Australia, Asia and Africa rose to 1.34 million ounces of gold and 48,000 tonnes of copper in the quarter. That compares with 1.15 million ounces of gold and 13,000 tonnes of copper in the third quarter of 2014.

All-in sustaining costs to produce one ounce of gold improved to $835 an ounce in the third quarter from $995 in the same quarter a year ago.

Newmont's stock is down 0.7 percent this year, one of the best-performing among large gold miners this year and slightly ahead of the S&P/TSX Global Gold Index, which is down 1.3 percent since January.

(Reporting by Nicole Mordant and Susan Taylor; Editing by Diane Craft and Alan Crosby)