EARFCN to Frequency: Complete LTE & 5G NR-ARFCN Guide

You are in the field. Signal is dropping on what should be Band 3 (1800 MHz). The scanner shows EARFCN 1300. Is that Band 3? Band 1? Without knowing the formula, you cannot tell. Knowing how to convert EARFCN to frequency — and back — is a fundamental skill that separates a junior technician from a senior RF engineer. This guide covers everything: the formulas, the band tables, the 5G NR extension, and how ARFCN values appear in live Layer 3 messages.

What is EARFCN?

EARFCN stands for E-UTRA Absolute Radio Frequency Channel Number. It is the LTE channel numbering scheme defined in 3GPP TS 36.101 Table 5.7.3-1. Rather than referencing a raw frequency in megahertz, every LTE cell broadcasts its EARFCN, and the receiver applies a formula to derive the actual center frequency.

The downlink conversion formula

The downlink center frequency for a given EARFCN is calculated as:

F_DL = F_DL_low + 0.1 × (N_DL - N_Offs-DL)

Where:

• F_DL_low is the lower edge of the downlink frequency band (MHz)
• N_DL is the EARFCN (downlink channel number)
• N_Offs-DL is the band-specific EARFCN offset defined in TS 36.101

Worked example — EARFCN 1300:

Band 3 has F_DL_low = 1805 MHz and N_Offs-DL = 1200. Therefore:

F_DL = 1805 + 0.1 × (1300 - 1200) = 1805 + 10 = 1815.0 MHz

EARFCN 1300 is Band 3, downlink at 1815.0 MHz. Not Band 1.

EARFCN range: 0 to 65535

LTE EARFCNs span from 0 to 65535. Each band occupies a specific contiguous sub-range of this space. For FDD bands, the uplink EARFCN is obtained by adding 18000 to the downlink EARFCN (band-specific offset applies — always verify in TS 36.101 Table 5.7.3-1). TDD bands have no separate UL EARFCN: the same channel number serves both directions.

Key EARFCN ranges — European and global bands

Band	DL Frequency	EARFCN Range	Region
B1	2100 MHz	0 - 599	Global
B3	1800 MHz	1200 - 1949	Europe/Asia
B7	2600 MHz	2750 - 3449	Europe
B20	800 MHz	6150 - 6449	Europe (rural)
B28	700 MHz	9210 - 9659	APAC/Africa

The key insight: Band 7 and Band 8 share an overlapping EARFCN region around 2750. Context matters — always verify the band indicator alongside the EARFCN when reading raw scanner output or Layer 3 messages.

NR-ARFCN for 5G NR

With 5G New Radio, the 3GPP working groups introduced NR-ARFCN (New Radio Absolute Radio Frequency Channel Number), defined in 3GPP TS 38.101-1 Table 5.4.2.1-1. The system is more complex than EARFCN because 5G NR spans an enormous frequency range — from 600 MHz sub-1 GHz bands all the way to 71 GHz mmWave.

Global frequency raster

Instead of band-specific low-edge anchors, NR-ARFCN uses a global frequency raster parameterized by three variables:

F_REF = F_REF-Offs + Δf_Global × (N_REF - N_REF-Offs)

For the sub-6 GHz range (FR1), the parameters are:

• Δf_Global = 15 kHz (raster step)
• F_REF-Offs = 0 MHz
• N_REF-Offs = 0

This gives a simple linear mapping: F_REF (kHz) = 15 × N_REF

For FR2 mmWave (24-52 GHz), Δf_Global = 60 kHz with a non-zero offset, and for FR2-2 (52-71 GHz), Δf_Global = 60 kHz with a higher offset. Always check TS 38.101-1 Table 5.4.2.1-1 for the exact parameters per frequency range.

Key NR-ARFCN examples

NR Band	Center Freq	NR-ARFCN Example	Use Case
n1	2100 MHz	423000	Indoor 5G
n3	1800 MHz	361000	Dense urban
n28	700 MHz	152000	Rural 5G
n41	2500 MHz	499200	TDD mid-band
n77	3700 MHz	648000	C-band 5G
n78	3500 MHz	632628	Europe 5G (3.5 GHz)

The single most important NR-ARFCN for European engineers: 632628 = 3500 MHz (Band n78). According to BEREC 2025 data, n78 at 3.5 GHz is the primary 5G band deployed by operators across virtually every EU member state. When you see NR-ARFCN 632628 in an RRC Reconfiguration message, you are looking at mainstream European 5G C-band.

Why NR-ARFCN values look so different from EARFCNs

An LTE EARFCN tops out at 65535. An NR-ARFCN for n78 sits around 620000-680000. This is not a coincidence — the NR-ARFCN raster is global (15 kHz steps from 0 Hz upward), while EARFCN is a patchwork of band-specific sub-ranges. Do not attempt to cross-map EARFCN values to NR-ARFCN: they are entirely separate numbering spaces.

Why EARFCN Matters in Field Diagnostics

Understanding EARFCN is not just an academic exercise. In live networks, every Layer 3 RRC message identifies cells by their ARFCN, not by their frequency. An engineer reading protocol traces without ARFCN knowledge is effectively reading in a foreign language.

EARFCN in RRC messages

Key Layer 3 messages that carry EARFCN or NR-ARFCN values:

• SystemInformationBlock Type 1 (SIB1): broadcasts the serving cell EARFCN
• MeasurementReport: UE reports neighbor cell EARFCN values with their measured RSRP/RSRQ
• RRCReconfiguration (Handover Command): specifies target cell EARFCN and PCI
• SIB24 (used in LTE for 5G NR reselection): carries NR-ARFCN of the target 5G cell

When you capture a MeasurementReport via your 3GPP protocol decoder and see a neighbor listed as EARFCN 6300 with RSRP -85 dBm, you need to instantly recognize: that is Band 20 (800 MHz), a low-band rural cell — not Band 3. The diagnosis path changes completely based on that identification.

Inter-RAT measurement events and ARFCN

B1 event (inter-RAT neighbor becomes better than threshold) and B2 event (serving cell falls below threshold while neighbor exceeds another) both reference the target RAT cell by EARFCN or NR-ARFCN. An engineer tuning B1/B2 thresholds for an LTE-to-5G NR reselection campaign must be able to map the configured NR-ARFCN back to the actual 5G band being targeted — otherwise threshold tuning is guesswork.

Intra-frequency vs. inter-frequency handover

Identifying whether a handover is intra-frequency or inter-frequency requires comparing the serving EARFCN with the target EARFCN in the Handover Command. If they match, the handover is intra-frequency (same carrier, different cell). If they differ, it is inter-frequency. The distinction matters for troubleshooting: inter-frequency failures often indicate a measurement gap configuration problem or a missing frequency layer in the neighbor list, while intra-frequency failures point to coverage overlap or PCI collision issues.

Using an EARFCN Calculator in the Field

Manual calculation is error-prone under field conditions. Applying the formula correctly requires knowing which band corresponds to a given EARFCN (the table lookup step), then applying the offset arithmetic. A single transcription error yields a wrong frequency — and a wrong diagnosis.

The practical solution is an online calculator. The EARFCN calculator on HiCellTek supports all standardized LTE bands across the full DL and UL EARFCN range. Enter the channel number, get the band, the downlink frequency, and the uplink frequency instantly.

Batch conversion for drive test log processing

When post-processing a drive test log containing thousands of EARFCN samples, manual conversion is not feasible. Common approaches:

• Scripted lookup table: a Python or Bash script that maps each EARFCN to its band and frequency using the TS 36.101 offset table loaded as a reference array
• API integration: some network testing platforms expose EARFCN-to-frequency endpoints that can be called during log post-processing pipelines
• Spreadsheet formula: for smaller datasets, a VLOOKUP or INDEX/MATCH against a band offset table works for one-off analyses

Common mistakes to avoid

Confusing DL and UL EARFCN: For FDD Band 3, the downlink EARFCN range is 1200-1949, but the uplink EARFCN range starts at 19200. An EARFCN of 19500 is NOT Band 3 downlink — it is Band 3 uplink. Always check the FDD UL/DL offset (typically 18000) and confirm against TS 36.101.

Applying EARFCN logic to NR-ARFCN: The two systems are structurally different. There is no fixed 18000 offset in NR-ARFCN. Uplink NR-ARFCN for FDD NR bands uses a different formula and different offset tables in TS 38.101-1.

Ignoring TDD bands: TDD LTE bands (B38, B39, B40, B41) have no separate UL EARFCN. The same EARFCN applies to both uplink and downlink. Attempting to add 18000 for a TDD band produces a nonsense result.

EARFCN in Automated Reports and MDM Systems

Beyond individual field sessions, EARFCN data appears routinely in automated network management contexts.

MDM fleet analysis

Mobile Device Management (MDM) platforms export device telemetry that typically includes the serving EARFCN alongside IMEI, RSRP, and throughput. To derive actionable insights from this telemetry, the EARFCN must be mapped to a band and frequency. A fleet of 10,000 devices showing 35% camped on Band 20 (EARFCN 6200-6400 range) when Band 3 coverage is available may indicate a misconfigured cell reselection priority — but only an engineer who can read EARFCN distributions will spot it.

IMEI and EARFCN correlation for compatibility audits

Combining EARFCN data with TAC/IMEI lookup enables device-network compatibility auditing. The EARFCN tells you which band the network cell is transmitting on. The IMEI TAC lookup (via the GSMA TAC database) tells you which bands that device model supports. Cross-referencing the two identifies devices that are physically present in a coverage area but incapable of camping on the available band — a common issue with budget devices that lack support for Band 28 or Band 20 in rural deployments.

Coverage heatmap generation

Drive test logs converted from raw EARFCN to band and frequency allow engineers to generate frequency-layer heatmaps: geographic representations showing which band is serving at each GPS coordinate. This is the foundation of any multi-band coverage audit and is essential for identifying areas where low-band (B20/B28) coverage is absent and only high-band (B3/B7) signal is available — leading to poor indoor penetration despite acceptable outdoor RSRP.

Conclusion

EARFCN and NR-ARFCN are the frequency language of 3GPP networks. Every cell in every Layer 3 message is identified by its channel number, not its frequency in megahertz. Mastering the conversion — knowing that EARFCN 1300 is Band 3 at 1815 MHz, that NR-ARFCN 632628 is Band n78 at 3500 MHz, that the UL offset in FDD differs from TDD — is what makes an RF engineer productive and precise in the field. Having a reliable conversion tool removes the arithmetic burden so attention stays on the diagnosis rather than the calculation.

Question for the comments: What EARFCN mismatch have you encountered in the field that caused an unexpected troubleshooting detour?