# -(_:_:) Subtract two measurements of the same Unit. ``` static func - (lhs: Measurement, rhs: Measurement) -> Measurement ``` ## Return Value A measurement of value `lhs.value - rhs.value` and unit `lhs.unit`. ## Discussion> precondition: The `unit` of `lhs` and `rhs` must be `isEqual`. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)