<!--
{
  "availability" : [
    "iOS: 16.0.0 -",
    "iPadOS: 16.0.0 -",
    "macCatalyst: 16.0.0 -",
    "macOS: 13.0.0 -",
    "visionOS: 1.0.0 -",
    "watchOS: 9.0.0 -"
  ],
  "documentType" : "symbol",
  "framework" : "HealthKit",
  "identifier" : "/documentation/HealthKit/HKWorkoutActivity/duration",
  "metadataVersion" : "0.1.0",
  "role" : "Instance Property",
  "symbol" : {
    "kind" : "Instance Property",
    "modules" : [
      "HealthKit"
    ],
    "preciseIdentifier" : "c:objc(cs)HKWorkoutActivity(py)duration"
  },
  "title" : "duration"
}
-->

# duration

The activity’s duration, measured in seconds.

```
var duration: TimeInterval { get }
```

## Discussion

HealthKit calculates the [`duration`](/documentation/HealthKit/HKWorkoutActivity/duration) as the elapsed time between the activity’s [`startDate`](/documentation/HealthKit/HKWorkoutActivity/startDate) and [`endDate`](/documentation/HealthKit/HKWorkoutActivity/endDate), ignoring any pause periods. If an activity is currently in progress, it has a `nil`-valued [`endDate`](/documentation/HealthKit/HKWorkoutActivity/endDate). In this case, HealthKit calculates the duration as the time between the [`startDate`](/documentation/HealthKit/HKWorkoutActivity/startDate) and the current time, ignoring any pause periods.

---

Copyright &copy; 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)