You’re only getting 30Hz through USB-C to HDMI because either your adapter, your monitor, or your laptop’s USB-C port is limited to HDMI 1.4 — which caps 4K output at 30Hz and cannot push 60Hz at higher resolutions. Fixing it means identifying which link in the chain is the bottleneck.
In this guide
30Hz through USB-C to HDMI is almost always caused by an HDMI 1.4 adapter, an HDMI 1.4 monitor input, or a USB-C port that simply does not output high-bandwidth video. All three must support HDMI 2.0 (or you need to switch to DisplayPort) to reach 60Hz at 4K.
- Your USB-C adapter is rated for HDMI 2.0 or higher
- Your monitor’s HDMI input is version 2.0 or higher
- Your laptop’s USB-C port supports full DisplayPort Alt Mode bandwidth
- No other peripherals are sharing the USB-C port’s bandwidth
- Your adapter only supports HDMI 1.4 (very common with cheap adapters)
- Your monitor’s HDMI port is version 1.4
- Your laptop’s USB-C port has limited video output (e.g., original MacBook 12-inch)
- The USB-C port is sharing bandwidth with a built-in USB hub, Ethernet, or webcam
The Real Reason: HDMI 1.4 vs HDMI 2.0
HDMI 1.4 has a maximum bandwidth of 10.2 Gbps. At 4K resolution, that only leaves enough room for 30Hz. HDMI 2.0 raises bandwidth to 18 Gbps, which is enough for 4K at 60Hz. If any part of your chain — adapter, cable, or monitor port — is HDMI 1.4, you hit the ceiling at 30Hz.
Many USB-C to HDMI adapters sold today still use HDMI 1.4 internally, even if the packaging claims 4K support. Always check whether it says 4K@60Hz specifically. If it just says “4K,” assume 30Hz.
Check Each Part of the Chain
| Component | What to Check | Fix |
|---|---|---|
| USB-C adapter | Does it say HDMI 2.0 and 4K@60Hz? | Replace with a verified HDMI 2.0 adapter |
| HDMI cable | Is it High Speed or Premium High Speed? | Use a Premium High Speed HDMI cable |
| Monitor HDMI port | Check monitor spec sheet for HDMI version | Use a different input (DisplayPort if available) |
| Laptop USB-C port | Does it support DisplayPort Alt Mode fully? | Check manufacturer specs; try a different port |
Bandwidth Sharing Makes It Worse
Some monitors connect via USB-C and also act as a USB hub, passing through Ethernet, webcam data, or other USB devices over the same cable. All of that competes for bandwidth on the same USB-C connection. The result is less headroom for video data, which can push the refresh rate down to 30Hz even if your adapter is technically capable of more.
If your monitor has a built-in hub, try disconnecting peripherals plugged into it and see if the refresh rate option unlocks in your display settings.
Switch to DisplayPort If You Can
DisplayPort Alt Mode over USB-C has more available bandwidth than HDMI in most implementations. If your monitor has a DisplayPort input, use a USB-C to DisplayPort cable instead of a USB-C to HDMI adapter. This often resolves 30Hz issues entirely without needing to upgrade anything else.
Quick Fixes to Try Right Now
- Open display settings and manually set the refresh rate to 60Hz — sometimes it defaults to 30Hz even when 60Hz is available
- Swap the adapter for one explicitly rated for HDMI 2.0 and 4K@60Hz
- Try a USB-C to DisplayPort cable instead
- Disconnect any USB devices plugged into your monitor’s hub ports
- Try a different USB-C port on your laptop — not all ports have equal video capability
- Check your monitor’s manual to confirm which HDMI port version each input is
Frequently Asked Questions
Can a USB-C to HDMI cable do 4K 60Hz?
Only if the adapter uses HDMI 2.0, your laptop’s USB-C port supports full DisplayPort Alt Mode bandwidth, and your monitor’s HDMI input is also 2.0 or higher.
Why does my display settings not show 60Hz as an option?
Windows and macOS only show refresh rates your current hardware chain can support. If 60Hz is missing, something in the chain is limiting you to 30Hz.
Does the HDMI cable matter?
Yes. Use a Premium High Speed HDMI cable (labeled 18Gbps) for 4K@60Hz. Standard High Speed cables are only rated for 10.2Gbps and may cause 30Hz caps or signal dropouts.
The fix is almost always a cheap or outdated HDMI 1.4 adapter, a monitor port that is only HDMI 1.4, or a USB-C port that was never designed for full video bandwidth. Work through the chain one step at a time and you will find the culprit quickly.
For official technical specifications, see the official documentation.
Related: Can USB-C Connect to HDMI? | Why Is USB-C to HDMI Not Working?