How to Fix Inconsistent Physics Across Frame Rates

Physics that changes with frame rate is being stepped with a variable delta. A fixed timestep makes it consistent on every machine. Here is how.

How to fix it

1. Use a fixed timestep

Step the physics simulation at a constant rate (for example 60 times a second) regardless of how fast the game renders. Variable-step integration gives different results at different frame rates, breaking determinism and feel.

2. Accumulate and run fixed steps

Accumulate elapsed render time and run as many fixed physics steps as it covers each frame. This decouples simulation from frame rate so behaviour is identical at 30 or 144 FPS.

3. Interpolate the visuals

With a fixed physics step, render positions can lag the visual frame. Interpolate object visuals between the last two physics states so motion looks smooth despite the fixed simulation rate.

Catching the ones you can't reproduce

The hardest version of this to fix is the one you can't reproduce — it only happens on a player's hardware, OS, driver, or save state, under conditions that simply aren't present on your machine. A report that says “it crashed” or “it froze” gives you nothing to act on, so the bug survives release after release while quietly costing you players.

Automatic error capture closes that gap. Each failure arrives with its full stack trace, the device and OS, the build number, and a breadcrumb trail of what the player did right before it broke, so even a failure you have never seen becomes a specific, reproducible issue. Fold identical failures into one signature ranked by how many players each hits, and your worklist sorts itself worst-first instead of arriving as a stream of vague complaints.

This is where a tool like Bugnet earns its place. Its SDK captures every your game error automatically with the full stack trace plus device, OS, memory, build, and game-state context, folds duplicates into one grouped issue with an occurrence count, and ties each to the build it first appeared on — so you fix the problem that hurts the most players first and confirm it is gone when its signature disappears from the next release.