TOKYO, March 9 (Reuters) - Nikkei futures and options contracts expiring in March were forecast to settle at 21,575.45, market participants said on Friday, citing estimates by brokerages.

The closely watched settlement price, known in Japan as the special quotation, or "SQ", is calculated from the opening prices of the 225 shares in the Nikkei average on the second Friday of the month.

It is calculated monthly for options and every three months for futures. The official settlement price will be announced after the market closes on Friday. (Reporting by Ayai Tomisawa Editing by Chang-Ran Kim)