How do I convert a 5G NR Timing Advance to distance?

TA corrects for the round-trip propagation delay, so distance is one-way: d = (TA × 16 × 2^(−μ) × T_c × c) / 2, where T_c ≈ 0.509 ns is the NR basic time unit (TS 38.211) and μ is the numerology. Pick your subcarrier spacing and the tool returns the UE-to-gNB distance and the one-way delay.

How far is one TA step at each numerology?

One TA unit corresponds to about 1.22 m at 15 kHz SCS (μ=0), 0.61 m at 30 kHz, 0.305 m at 60 kHz and 0.152 m at 120 kHz. The higher the subcarrier spacing, the finer the timing step, so the distance resolution improves as you move up in numerology.

How accurate is TA-based distance?

It is a coarse estimate, not a positioning fix. TA is quantised to discrete steps and the value reflects the signal path length, which includes reflections and multipath rather than the straight-line distance. Treat it as a rough range (within tens to hundreds of metres depending on SCS), useful for cell-edge checks, not precise location.

Why divide by two when going from TA to distance?

The Timing Advance compensates for the signal travelling from the UE to the gNB and back, so it represents the round-trip time. Dividing the resulting distance by two gives the one-way UE-to-gNB distance, which is what you actually want.

TA to Distance Calculator

Convert 5G NR Timing Advance values to UE-gNB distance. Supports all numerologies.

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Timing Advance (TA) is how 5G NR and LTE keep UEs from different cell ranges arriving at the gNB synchronised on the air interface. The gNB measures the propagation round-trip delay and commands the UE to transmit earlier by N_TA basic time units so its uplink slots line up with everyone else's. Because TA is expressed in the basic time unit Tc (≈ 0.509 ns at μ = 0), and because the TA step scales with numerology (μ), a single TA value corresponds to different UE-to-gNB distances depending on the subcarrier spacing: ~78 m per unit at 15 kHz, ~39 m at 30 kHz, ~19.5 m at 60 kHz, and ~9.75 m at 120 kHz. This tool does the conversion in both directions — give it a TA and numerology and you get distance, or give it a distance and you get the TA value the gNB would send.

TA → Distance

Enter a Timing Advance value and numerology to get UE-to-gNB distance.

Timing Advance (TA_n)

Valid range 0–3846 for NR TA commands.

Subcarrier Spacing

UE Distance

61.0m

≈ 0.061 km · one-way from gNB

One-way Delay

203.45ns

Distance per TA unit

0.61m

A TA of 100 at 30 kHz SCS corresponds to a UE distance of 61 m (0.06 km) from the gNB.

Distance → TA

Reverse direction: enter a UE distance to see the required TA value.

Distance (metres)

Subcarrier Spacing

Required TA

1,640

exact: 1639.53

Round-trip Delay

6.671µs

How It Works

The formulas implemented here:

Tc = 1 / (Δf_max × N_f) = 1 / (480 kHz × 4096) ≈ 0.509 ns
t_round_trip = TA × 16 × 2^(-μ) × Tc   seconds
distance     = t_round_trip × c / 2    metres

μ = 0 (15 kHz SCS) → 1 TA unit ≈ 520.8 ns round-trip → 78 m one-way
μ = 1 (30 kHz SCS) → ≈ 39 m per TA unit
μ = 2 (60 kHz SCS) → ≈ 19.5 m per TA unit
μ = 3 (120 kHz SCS) → ≈ 9.75 m per TA unit

The MAC CE that carries the TA command is 6 bits wide in the RAR (values 0–63, coarse initial TA), and 6 bits in the TA MAC CE (−31..+32 adjustments) during connected mode. The ambiguity range of a single TA command therefore scales inversely with μ: high-band 120 kHz SCS sessions re-TA much more frequently than low-band 15 kHz sessions.

3GPP References

• TS 38.213 §4.2 — Timing advance
• TS 38.211 §4.1 — Basic time unit Tc = 1/(Δf_max × N_f)
• TS 38.321 §5.2 — MAC Timing Advance Command MAC CE
• TS 38.133 — Requirements for support of radio resource management

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How to convert Timing Advance to distance

Enter the TA value. Type the Timing Advance command value (valid range 0–3846 for NR).
Select the subcarrier spacing. Choose the numerology: 15, 30, 60 or 120 kHz.
Read the distance. See the estimated UE-to-gNB distance and the one-way propagation delay.
Or reverse it. Enter a distance instead to get the TA value the gNB would need to command.

Frequently asked questions

How do I convert a 5G NR Timing Advance to distance?: TA corrects for the round-trip propagation delay, so distance is one-way: d = (TA × 16 × 2^(−μ) × T_c × c) / 2, where T_c ≈ 0.509 ns is the NR basic time unit (TS 38.211) and μ is the numerology. Pick your subcarrier spacing and the tool returns the UE-to-gNB distance and the one-way delay.
How far is one TA step at each numerology?: One TA unit corresponds to about 1.22 m at 15 kHz SCS (μ=0), 0.61 m at 30 kHz, 0.305 m at 60 kHz and 0.152 m at 120 kHz. The higher the subcarrier spacing, the finer the timing step, so the distance resolution improves as you move up in numerology.
How accurate is TA-based distance?: It is a coarse estimate, not a positioning fix. TA is quantised to discrete steps and the value reflects the signal path length, which includes reflections and multipath rather than the straight-line distance. Treat it as a rough range (within tens to hundreds of metres depending on SCS), useful for cell-edge checks, not precise location.
Why divide by two when going from TA to distance?: The Timing Advance compensates for the signal travelling from the UE to the gNB and back, so it represents the round-trip time. Dividing the resulting distance by two gives the one-way UE-to-gNB distance, which is what you actually want.

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