Free tool · 3GPP TS 38.211 §4

5G NR numerology planner

One slider, every number: subcarrier spacing, slot and symbol duration, cyclic prefix lengths, slots per frame and FFT sizing — with the frame structure redrawn live as μ changes.

Pick a numerology

μ sets everything: SCS = 15 × 2μ kHz · TS 38.211 Table 4.2-1

10 ms frame1 ms subframeslotOFDM symbol
μSCSSymbols/slotSlots/subframeSlots/frameSlot durationSymbol (data)CP (normal)Range / typical use
Under the hood

Why the numbers are what they are

Δf = 15 kHz × 2μ  ·  Tslot = 1 ms / 2μ  ·  Tu = 1/Δf  ·  TCP ≈ 144 × Tc × 2−μ × 64

Everything scales together. Doubling μ doubles the subcarrier spacing, which halves the useful symbol time Tu = 1/Δf — and the slot (always 14 symbols with normal CP) halves with it. The CP shrinks in exact proportion, keeping its overhead at ≈ 6.7% for every numerology. The first symbol of every 0.5 ms gets a slightly longer CP so that the half-millisecond boundary stays aligned across all numerologies — that's why you see two CP values below.

The trade-off: high μ ⇒ short slots (low latency, good for FR2 phase noise) but small cells (short CP tolerates less delay spread). Low μ ⇒ generous CP for big macro cells but slower HARQ turnaround. 30 kHz is FR1's sweet spot; 120 kHz carries FR2 data; 240 kHz is SSB-only.

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FAQ

Common questions

What is numerology (μ) in 5G NR?
Numerology is the parameter μ ∈ {0…4} that sets the subcarrier spacing as 15 kHz × 2^μ. Unlike LTE's fixed 15 kHz, NR scales its whole time-frequency grid with μ: slot duration, symbol duration and cyclic prefix all halve each time μ increases by one (TS 38.211 §4.2).
Which subcarrier spacing is used where?
15 and 30 kHz carry data in FR1 (30 kHz is the workhorse for n78-style TDD), 60 kHz is optional in both ranges, 120 kHz carries data in FR2, and 240 kHz exists only for SSB transmission in FR2. Rel-17 added 480/960 kHz for the 57–71 GHz band.
Why does the slot get shorter at higher μ?
A slot is always 14 OFDM symbols (normal CP), and each symbol lasts 1/Δf plus its CP. Doubling Δf halves the symbol time, so the 14-symbol slot halves too: 1 ms at μ=0, 500 µs at μ=1, down to 62.5 µs at μ=4 — which is exactly how NR achieves low air-interface latency.
What is the cyclic prefix for and why two lengths?
The CP absorbs multipath delay spread so inter-symbol interference lands inside the guard instead of corrupting the FFT window. Within every 0.5 ms half-subframe the first symbol carries a slightly longer CP so that symbol boundaries of all numerologies line up at half-millisecond ticks.
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