ARFCN ⇄ Frequency
Bidirectional · snaps to the global raster · TS 38.104 §5.4.2
MHz
NREF
GSCN ⇄ SSB frequency
Synchronization raster · TS 38.104 §5.4.3
MHz
GSCN
The synchronization raster is where a UE searches for SSB during cell search. Below 3 GHz: SSREF = N·1200 kHz + M·50 kHz (GSCN = 3N + (M−3)/2). 3–24.25 GHz: SSREF = 3000 MHz + N·1.44 MHz (GSCN = 7499 + N). FR2: SSREF = 24250.08 MHz + N·17.28 MHz (GSCN = 22256 + N).
0 — 3000 MHz
ΔF = 5 kHz
3000 — 24250 MHz
ΔF = 15 kHz
24250 — 100000 MHz
ΔF = 60 kHz
Spectrum explorer
Tap a band — the converter follows you
Every operating band from TS 38.104 Table 5.2-1, grouped by range. Clicking a band loads its downlink (or TDD) centre frequency into the converter above.
Band reference
NR operating band table
Search by band number, frequency or duplex mode. UL/DL ranges in MHz per 3GPP TS 38.104 Table 5.2-1.
| Band | Common name | Duplex | Uplink (MHz) | Downlink (MHz) | Range |
|---|
Under the hood
The exact 3GPP math this tool runs
FREF = FREF-Offs + ΔFGlobal × ( NREF − NREF-Offs )
Pick the raster segment. The global raster has three granularities: 5 kHz below 3 GHz, 15 kHz from 3 GHz to 24.25 GHz, and 60 kHz above 24.25 GHz (FR2).
Worked example — ARFCN 632628. It is ≥ 600000, so the 15 kHz segment applies: F = 3000 MHz + 0.015 × (632628 − 600000) = 3000 + 489.42 = 3489.42 MHz — mid n78.
Reverse direction snaps. 3500.000 MHz is not on the 15 kHz raster: N = 600000 + (3500 − 3000)/0.015 = 633333.33. The nearest integer 633333 corresponds to 3499.995 MHz — that 5 kHz difference is why real deployments quote ARFCN, not MHz.
Bands are just ranges. Once you have the frequency, the band is whichever Table 5.2-1 window contains it — and several often do (3500 MHz ∈ n77 and n78), which is exactly what the chips above show.
FAQ
Common questions
What is an NR-ARFCN?
NR-ARFCN (NR Absolute Radio Frequency Channel Number) is an integer 0…3279165 that addresses an RF reference frequency on the 5G NR global frequency raster (TS 38.104 §5.4.2). RRC signalling, drive-test logs and OSS configs all exchange frequencies as ARFCNs because integers are unambiguous — no rounding, no unit confusion.
Why does my frequency get snapped?
Only frequencies that sit exactly on the raster have an ARFCN. The calculator finds the nearest raster point and shows the exact snapped value — e.g. 3500.000 MHz → ARFCN 633333 → 3499.995 MHz. If you see a snap of more than half the raster step, the input wasn't a valid carrier reference frequency.
ARFCN vs GSCN — what's the difference?
ARFCN addresses any carrier frequency on the fine global raster. GSCN addresses the much sparser synchronization raster where SSBs may sit, so a UE searching for cells only has to test a few thousand candidate positions instead of millions. A cell has both: its carrier ARFCN and its SSB GSCN.
Why do several bands match one frequency?
3GPP band ranges overlap heavily — 3500 MHz is inside both n77 (3300–4200) and n78 (3300–3800); 2110–2170 MHz is DL of n1, n65 and n66. Which band applies is a regulatory/regional choice, not a property of the frequency itself, so the tool lists every match with its UL/DL role.
Does this work for FR2 / mmWave?
Yes — the 60 kHz raster segment above 24.25 GHz and the FR2 synchronization raster (GSCN 22256…26639, 17.28 MHz steps) are both implemented, covering n257…n263 up to 71 GHz.
Where do the formulas come from?
Everything implements 3GPP TS 38.104 — §5.4.2 for the NR-ARFCN global raster, §5.4.3 for the GSCN synchronization raster, and Table 5.2-1 for operating bands. No approximations: the same math your gNB config uses.