UPDATE 2-Box's revenue forecast misses estimates, shares down 12 pct

(Adds forecast; updates share price)

Feb 28 (Reuters) - Cloud storage company Box Inc's revenue forecast for the current quarter missed Wall Street estimates amid slowing growth in paid customers in the fourth quarter.

The company's shares fell nearly 12 percent to $21.20 in extended trading on Wednesday.

The rate of growth in paid customers slowed to 2,000 in the quarter, compared with 4,000 additions in the third quarter.

Box, which competes with Dropbox Inc, Microsoft Corp's OneDrive and Google's Drive, had 82,000 paid customers in the fourth quarter, up from 80,000 in the third quarter.

The company forecast revenue for the first quarter in the range of $139 million to $140 million as per new accounting standards, below analysts' estimates of $144.3 million.

Box said it expects an adjusted loss per share for the first quarter to be in the range of 8 cents to 9 cents. Analysts on average were expecting a loss of 8 cents.

The company's net loss narrowed to $32.7 million, or 24 cents per share, in the quarter ended Jan. 31 from $36.9 million, or 28 cents per share, a year earlier.

On an adjusted basis, the loss was 6 cents per share. Analysts on average had expected a loss of 8 cents per share, according to Thomson Reuters I/B/E/S.

Redwood City, California-based Box said its revenue rose 24.3 percent to $136.7 million, in line with Wall Street estimates. (Reporting by Arjun Panchadar and Shariq Khan in Bengaluru; Editing by Maju Samuel)