UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): May 21, 2013

Nanometrics Incorporated

(Exact name of registrant as specified in its charter)

1550 Buckeye Drive, Milpitas, California 95035

(Address of principal executive offices and zip code)

Registrant’s telephone number, including area code: (408) 545-6000

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Item 5.02. Departure of Directors or Principal Officers; Election of Directors; Appointment of Principal Officers; Compensatory Arrangements of Certain Officers

Appointment of New Board Member to a Committee of the Board

On May 21, 2013, the Board of Directors (the “Board”) of Nanometrics Incorporated appointed Edward J. Brown, Jr., to serve on the Compensation Committee of the Board. Mr. Brown was initially elected to the Board on February 19, 2013, as reported in a Form 8-K filed by Nanometrics on February 22, 2013, and at that time had not yet been appointed to any committees of the Board.

Approval of 2005 Equity Incentive Plan

On May 24, 2013, the stockholders of Nanometrics approved Nanometrics’ 2005 Equity Incentive Plan, as amended and restated, referred to as the “Incentive Plan,” which amendment and restatement included the following material changes to the Incentive Plan:

Approval of the amended 2005 Equity Incentive Plan by the Nanometrics stockholders also constituted approval of the terms and conditions set forth therein that permits Nanometrics to grant stock options and performance awards under the Incentive Plan that may qualify as “performance-based compensation” within the meaning of Section 162(m) of the Internal Revenue Code.

The Incentive Plan permits the grant of stock options, stock appreciation rights, restricted stock, restricted stock units and performance shares to (1) employees of Nanometrics and any parent or subsidiary, (2) consultants who provide services to Nanometrics and any parent or subsidiary, and (3) directors of Nanometrics.

The above description of the Incentive Plan is a summary only and is qualified in its entirety by reference to the complete text of the Incentive Plan, which is appended to Nanometrics’ Proxy Statement filed with the Securities and Exchange Commission on April 10, 2013, and available on the SEC’s website (the “Proxy Statement”).

Item 5.07. Submission of Matters to a Vote of Security Holders

Nanometrics Incorporated held its Annual Meeting of Stockholders on May 24, 2013. The following is a brief description of each matter voted upon at the Annual Meeting, as well as the final tally of the number of votes cast for or withheld for each director, and for or against each other matter, and the number of abstentions and broker non-votes with respect to each matter. A more complete description of each matter is set forth in the Proxy Statement.

1. Nanometrics’ stockholders elected each of the directors proposed by Nanometrics for election, to serve until Nanometrics’ 2014 Annual Meeting of Stockholders or until his respective successor has been elected and qualified. The tabulation of votes on this matter was as follows:

There were 2,689,284 broker non-votes for this proposal.

2. Nanometrics’ stockholders approved, on an advisory basis, a resolution approving the compensation of Nanometrics’ named executive officers, as disclosed in the Proxy Statement. The tabulation of votes on this matter was as follows:

3. Nanometrics’ stockholders approved Nanometrics’ 2005 Equity Incentive Plan, as amended and restated, as described in the Proxy Statement. The tabulation of votes on this matter was as follows:

4. Nanometrics’ stockholders ratified the selection of PricewaterhouseCoopers LLP as the independent registered public accounting firm of Nanometrics for its fiscal year ending December 28, 2013. The tabulation of votes on this matter was as follows:

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.