Quick Answer
ExpressLRS (ELRS) is an open-source radio control protocol for FPV drones that uses Semtech LoRa technology to deliver 2-4ms latency and 10km+ range. It runs on 2.4GHz or 868/915MHz bands with receivers starting under £15. Version 4.0 arrived in February 2026, adding smarter dynamic power, automatic antenna modes, and a customizable arming switch. Most FPV pilots choose ELRS over proprietary alternatives like Crossfire because it is cheaper, receives faster firmware updates, and works across all major radio manufacturers.
What Is ExpressLRS?
ExpressLRS, commonly called ELRS, is a high-performance radio control link protocol built on LoRa (Long Range) technology from Semtech. Unlike closed proprietary systems such as Crossfire from Team BlackSheep, ELRS is completely open-source. Anyone can contribute code, build hardware, or modify the firmware.
The protocol uses ESP32 or ESP8285 microcontrollers paired with Semtech SX127x or SX128x radio chips. This combination provides packet rates up to 1000Hz on 2.4GHz with latency as low as 2-4 milliseconds. At the same time, the system maintains excellent range, with pilots regularly achieving flights beyond 10 kilometres on standard hardware.
Because it is open-source, a large community of developers constantly improves the firmware. New features arrive regularly, from dynamic transmission power to WiFi-based firmware updates and built-in flight controller configuration.
Why ELRS Became the FPV Standard
Several factors pushed ELRS to dominate the FPV radio control market:
Cost: ELRS receivers typically cost between £10 and £25, compared to £30-50 or more for proprietary alternatives. This price difference adds up quickly when you fly multiple drones.
Performance: The low latency and high refresh rates suit racing and freestyle pilots who need instant stick response. At 500Hz packet rate on 2.4GHz, the link feels as direct as a wired connection.
Hardware variety: Manufacturers including RadioMaster, BetaFPV, HappyModel, and iFlight produce ELRS equipment. You can mix and match transmitters and receivers from different brands without compatibility issues.
Community support: Documentation, tutorials, and firmware updates come from a global community. Problems get solved fast, and new features appear regularly.
2.4GHz vs 868/915MHz ELRS
ELRS operates on two frequency bands, each with distinct advantages:
| Frequency | Best For | Packet Rate | Range |
|---|---|---|---|
| 2.4GHz | Racing, freestyle, park flying | Up to 1000Hz | 5-15km typical |
| 868/915MHz | Long range, mountain surfing | Up to 1000Hz | 20-40km+ typical |
Most pilots start with 2.4GHz because it offers faster response times and works well for typical flying distances. The 868MHz (EU) and 915MHz (US) versions suit pilots who prioritise maximum range over latency.
Both frequencies use the same receivers, such as the Happymodel EP1 TCXO receiver for 2.4GHz or the BetaFPV ELRS Nano available in both bands.
ELRS vs Crossfire: Which Should You Choose?
TBS Crossfire was the gold standard for long-range FPV for years, but ELRS has closed the gap and overtaken it for most use cases:
| Feature | ELRS | Crossfire |
|---|---|---|
| Latency | 2-4ms (2.4GHz) | ~7ms (150Hz) |
| Max packet rate | 1000Hz | 150Hz |
| Receiver cost | £10-25 | £30-50 |
| Frequency bands | 2.4GHz + 868/915MHz | 868/915MHz (Tracer for 2.4GHz) |
| Open source | Yes | No |
| Firmware updates | Community, frequent | TBS Agent, less frequent |
| Setup | Configurator + WiFi | Plug and play with OLED |
| Range (typical) | 5-15km (2.4GHz), 20-40km (900MHz) | 20-40km+ (900MHz) |
For most pilots, ELRS provides better value and performance. Crossfire still appeals to pilots who want plug-and-play simplicity and extreme range reliability. Many experienced pilots run ELRS 2.4GHz for racing and freestyle and either Crossfire or ELRS 868MHz for dedicated long-range builds.
What Is New in ELRS 4.0 (February 2026)
ExpressLRS 4.0 is a major release with significant improvements. It is not backward compatible with 3.x or 2.x firmware, so all devices must be updated together.
Key changes:
- Customizable arming switch — Channel 5 is freed up as a regular channel. Assign any switch for arming.
- Smarter dynamic power — Adjusts transmit power more intelligently, giving better signal without constantly running at maximum output. Improves radio battery life and link stability.
- Automatic antenna modes — The system negotiates True Diversity or Gemini mode based on your hardware. No manual configuration needed.
- Faster telemetry — Telemetry bandwidth is doubled in Gemini mode and 1.3x faster in standard modes.
- Redesigned WebUI — Modern interface for configuring your TX module and receivers via WiFi.
- GPS location tag — Connect a GPS unit directly to the receiver for tracking data sent back as telemetry.
- Full power DJI Air Unit without FC — Receivers can send arm signals directly to DJI Air Units for fixed-wing builds without a flight controller.
Important: ELRS 4.0 drops support for STM32-based hardware. You need EdgeTX 2.11.0 or higher. A new Lua script is required for your radio. Back up your settings before updating.
For step-by-step firmware update instructions, see our guide on how to update ExpressLRS firmware.
Getting Started with ELRS
To use ELRS, you need a compatible transmitter and receiver. Popular radio controllers include the RadioMaster Boxer with built-in ELRS and the RadioMaster TX15, both of which offer excellent value and performance out of the box.
Binding: Power cycle the receiver three times to enter bind mode, then trigger binding from your transmitter. Once bound, the connection persists automatically.
Binding phrases: ELRS uses a binding phrase (at least 8 characters) instead of traditional button binding. Set the same phrase on both your TX module and receiver when flashing firmware. This phrase seeds the frequency hopping pattern so your devices find each other.
Firmware matching: Your TX module and all receivers must run the same major version (all 3.x or all 4.x). Mismatched versions will not bind.
Betaflight setup: In the Ports tab, enable Serial RX on the UART connected to your receiver. In the Receiver tab, set mode to Serial (via UART) and provider to CRSF. Enable telemetry. Apply the ExpressLRS Link Preset from the Presets tab for your chosen packet rate.
ELRS Lua Script: Install the latest Lua script on your radio's SD card for configuring packet rate, power, and binding directly from your transmitter screen.
Explore our full range of radio receivers and R/C transmitters to find the right setup for your build.
Dynamic Power Explained
ELRS uses dynamic power to adjust your transmitter's output on the fly. Instead of always transmitting at maximum power, the system monitors link quality (LQ) and increases power only when needed. This saves battery on your radio, reduces interference with other pilots, and maintains a stable link.
In ELRS 4.0, the dynamic power algorithm was significantly improved. It responds faster to signal degradation and backs off more quickly when conditions improve. The result is more stable LQ readings and longer radio battery life.
FAQ
Is ELRS better than Crossfire?
For most pilots, yes. ELRS offers lower cost and faster packet rates on 2.4GHz. Crossfire has a longer heritage and some pilots prefer its 868/915MHz performance for extreme range. Crossfire is more plug-and-play, whilst ELRS needs slightly more setup. For the majority of FPV pilots, ELRS provides better value.
What frequency is best for ELRS?
2.4GHz is the best starting point for most pilots. It offers the fastest response times (up to 1000Hz packet rate) and 5-15km typical range. Switch to 868MHz (EU) or 915MHz (US) only if you specifically need maximum range for long-range or mountain surfing flights.
Do I need a licence to use ELRS?
No. ELRS operates on licence-exempt ISM bands (2.4GHz and 868/915MHz), so no additional radio licence is required. You still need the standard CAA Operator ID and Flyer ID to fly drones legally in the UK.
Can I use any ELRS receiver with any ELRS transmitter?
Yes, all ELRS equipment is cross-compatible regardless of manufacturer, as long as both transmitter and receiver use the same frequency band and the same major firmware version (all 3.x or all 4.x).
How do I update ELRS firmware?
Use the ExpressLRS Configurator desktop app to build and flash firmware. For receivers, the most common method is Betaflight Passthrough via USB. TX modules and receivers can also be updated over WiFi. Always match major firmware versions across all devices. See our full ELRS firmware update guide for step-by-step instructions.
What is a binding phrase in ELRS?
A binding phrase is a text string (minimum 8 characters) you set when flashing firmware to both your TX module and receiver. It acts as an anti-collision mechanism, seeding the frequency hopping pattern so your devices connect. All devices with the same binding phrase on the same frequency band will bind automatically. It is not for security or encryption.
Is ELRS 4.0 compatible with 3.x receivers?
No. ELRS 4.0 is not backward compatible with any previous version (3.x, 2.x, or 1.x). All transmitters and receivers in your fleet must be on 4.x to bind and operate together. Back up your settings before updating, as the upgrade may wipe existing configurations.