Share-based compensation	6 Months Ended
Share-based compensation	Jun. 30, 2025
Share-Based Payment Arrangement [Abstract]
Share-based compensation	Share-based compensation Prior to the Spin-off, key employees of the Company participated in Parent’s share-based compensation plans. All awards granted under these plans were based on Parent’s ordinary shares. Prior to the Spin-off, share- based compensation expense was allocated to the Company based upon the portion of the Parent’s share-based compensation plans in which the Company employees participated. At the time of the Spin-off, each outstanding Parent performance stock option, performance share unit, and restricted share unit held by a Company employee were converted into Company awards using a formula designed to preserve the intrinsic value of the awards immediately prior to and subsequent to the Spin-off. The converted awards will continue to vest over the original vesting period, which is generally three years from the grant date for performance share units and restricted share units, and five years from the grant date for performance stock options. The incremental compensation expense related to the conversion of the share-based awards was immaterial to the financial statements. Effective June 23, 2025, the Company established the Amrize Ltd 2025 Omnibus Incentive Plan (the “2025 Plan”). A total of 25,500,000 shares are authorized for issuance under the 2025 Plan. The 2025 Plan provides for the grant of share options (including incentive stock options (“ISOs”) and nonqualified stock options), share appreciation rights (“SARs”), restricted shares, restricted share units (“RSUs”), performance share units (“PSUs”), other share-based awards, share bonuses, cash awards and substitute awards. Also, in connection with the Spin-off, the Company established the Amrize Ltd Employee Stock Purchase Plan (“the ESPP”). The initial maximum number of shares which will be authorized for sale under the ESPP is equal to 11,300,000 shares. The ESPP is designed to allow eligible employees of the Company to purchase shares with their accumulated payroll deductions. The purpose of the ESPP is to assist eligible employees in acquiring an ownership interest in the Company, to align such employees’ interests with those of the Company’s shareholders and to encourage such employees to remain in the employment of the Company. Share-based compensation expense The Company recognizes an expense for share-based compensation plans based on the estimated fair value of the related awards. The Company measures share-based compensation awards using fair value-based measurement methods determined at the grant date. The compensation expense is recognized using the straight-line method over the requisite service period for time-based awards. For awards vesting based on market conditions, compensation expense is recognized whether or not the market condition is met, as long as the service condition is met. For awards vesting based on performance conditions, compensation expense is recognized over the requisite service period only if it is probable that the performance condition will be achieved. The Company reassesses the probability of vesting at each reporting period and adjusts the compensation expense based on its probability assessment. Total share-based compensation expense for the three and six months ended June 30, 2025 and 2024 and the respective income tax benefit recognized was immaterial to these unaudited condensed consolidated financial statements.