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Proposal - Missing dedicated "Rubber Band" physics in BouncingScrollPhysics causes low iOS fidelity #181752
Description
Currently, BouncingScrollPhysics in Flutter uses a single SpringDescription for both momentum scrolling (flings) and the overscroll recovery (snap-back/rubber band effect).
This design forces a compromise:
- If we tune the spring for a natural scroll feel, the snap-back becomes too loose and "floaty" compared to native iOS.
- If we tune it for a snappy return, the scrolling becomes too stiff.
As a result, Flutter's iOS scroll feel lacks the characteristic "heavy and snappy" rubber band effect found in UIScrollView, creating an "uncanny valley" effect for users.
Video
online-video-cutter.com.mp4
Describe the solution
Native iOS behaves as if it uses a different physical property when snapping back from an overscroll. Flutter should implement a dedicated spring simulation for this specific phase.
I have analyzed the motion curves of native iOS and found that separating the spring logic significantly improves fidelity.
Proposed Logic:
- Keep the existing spring for standard scrolling to maintain smoothness.
- Apply a specific "Rubber Band Spring" when the scroll position is out of bounds and the gesture ends.
- Empirically tuned values for this spring:
mass: 1.0,stiffness: 1e5 * lambda^2,damping: 100001 * lambda.
Note
The constants were specially tuned to achieve exponential damping for the spring.
Additional context
I have measured and compared the scroll position over time between:
- Native iOS (UIScrollView)
- Current Flutter
- New Flutter implementation
As shown in the graph, the current Flutter implementation (Cyan) exhibits a significantly slower recovery compared to native iOS. It lacks the initial 'snap' (stiffness) and takes considerably longer to settle (~0.81s) compared to the native duration (~0.63s), leading to the perceived "floaty" behavior.
In contrast, the new implementation (Brown) closely aligns with the native curve (Blue) in trajectory.
I have a PR ready with this fix.
Activity
MTtankkeo commentedon Feb 8, 2026
Note
It looks like native platforms just use an exponential decay approach for the rubber band animation.
1.mov
[-]Missing dedicated "Rubber Band" physics in BouncingScrollPhysics causes low iOS fidelity[/-][+]Proposal - Missing dedicated "Rubber Band" physics in BouncingScrollPhysics causes low iOS fidelity[/+]flutter-triage-bot commentedon Jun 23, 2026
This issue is assigned to @MTtankkeo but has had no recent status updates. Please consider unassigning this issue if it is not going to be addressed in the near future. This allows people to have a clearer picture of what work is actually planned. Thanks!
victorsanni commentedon Jul 28, 2026
Is this one of the issues called out in #103762?
MTtankkeo commentedon Jul 28, 2026
Yes. This issue specifically focuses on the overscroll bounce behavior mentioned in #103762. While #103762 covers several differences between Flutter and native iOS scrolling physics, this proposal isolates the snap-back phase and suggests using a dedicated simulation for it.
Add dedicated rubber band spring for overscroll recovery in BouncingS…
github-actions commentedon Sep 29, 2026
This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of
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