Adaptive sync technologies like FreeSync and G-Sync only work within a range of refresh rates. So what happens when your frame rate drops below that range, say to 35 FPS on a panel whose sync window starts at 48 Hz? That is where Low Framerate Compensation, or LFC, quietly saves the experience. This explainer covers what LFC does, when it kicks in, and why the VRR range on the box matters.
The Problem LFC Solves
Every variable refresh monitor has a supported window, for example 48-144 Hz. Inside it, the panel refreshes exactly when the GPU delivers a frame, eliminating tearing and stutter. But if your frame rate falls under the lower bound, the panel can no longer match it directly, and you would get tearing or judder at exactly the moment smoothness matters most.
How the VRR Window Behaves
| Frame rate | Panel window 48-144 Hz | Result |
|---|---|---|
| 120 FPS | Inside window | Direct sync, smooth |
| 60 FPS | Inside window | Direct sync, smooth |
| 40 FPS | Below window | LFC engages |
| 30 FPS | Below window | LFC doubles to 60 Hz |
How LFC Works
When your frame rate drops below the panel’s minimum, LFC repeats each frame to keep the refresh rate inside the supported window. At 30 FPS the monitor displays each frame twice for an effective 60 Hz, or three times for 90 Hz. The image you see still updates at 30 unique frames, but the panel keeps refreshing within its sync range so tearing and flicker are avoided.
Why the Range Ratio Matters
LFC only works reliably when the maximum refresh is at least about 2.0 to 2.5 times the minimum. A 48-144 Hz panel has a ratio of 3, so LFC works well. A panel with a narrow window like 48-75 Hz has a ratio below 2, which makes clean frame multiplication difficult, so it may lack LFC entirely. When shopping, a wide VRR range is a sign of better low-FPS behavior.
Do You Need to Turn It On?
LFC is automatic. As long as adaptive sync is enabled and your panel supports a wide enough range, LFC engages on its own the moment your frame rate dips below the window. There is no separate switch to flip.
LFC, G-Sync, and FreeSync Naming
Different brands wrap the same underlying idea in their own labels. NVIDIA’s G-Sync modules handle low frame rates natively across the full range, while FreeSync relies on LFC to cover frames below the panel’s minimum, provided the range ratio supports it. When you see a monitor certified for both FreeSync and G-Sync Compatible, the low-FPS behavior still depends on that VRR window width, so the certification alone does not guarantee flawless low-frame-rate handling.
This is why two monitors with the same maximum refresh can feel different when your frame rate sags. A panel with a 48-144 Hz window multiplies frames cleanly, while one advertised only from 60 Hz upward has no room for LFC and will tear or judder below 60 FPS. Reading the full VRR range in the spec sheet, not just the headline refresh rate, tells you whether a monitor will stay smooth when a demanding game pushes your frame rate down.
FAQ
Does LFC add input lag?
LFC’s frame repetition is designed to be nearly invisible and adds negligible latency compared to the alternative of tearing or judder. You are still seeing your true low frame rate, just presented within the panel’s sync window, so responsiveness tracks your actual FPS.
How do I know if my monitor supports LFC?
Check the VRR range in the specifications. If the maximum refresh is roughly twice the minimum or more, such as 48-144 Hz, LFC is almost certainly supported. Very narrow ranges may not support it, which is worth knowing if you often dip into low frame rates.
Bottom Line
LFC is the safety net that keeps adaptive sync working when your frame rate falls below the panel’s minimum, by repeating frames to stay inside the VRR window. It runs automatically and depends on a wide enough refresh range, so favor monitors with a broad window like 48-144 Hz or better if smooth low-FPS gameplay matters to you.
