---
title: baseCurve
framework: healthkit
role: symbol
role_heading: Instance Property
path: healthkit/hkcontactslensspecification/basecurve
---

# baseCurve

Part of the contact’s fit, it measures the curve of the back side of the contact, measured in mm.

## Declaration

```swift
@NSCopying var baseCurve: HKQuantity? { get }
```

## Discussion

Discussion The property’s range is 7.8 to 9.2 mm.

## See Also

### Accessing the specification’s data

- [diameter](healthkit/hkcontactslensspecification/diameter.md)