How is BLE range calculated?

Range is determined by the link budget: LB = TX_power + TX_antenna_gain + RX_antenna_gain - RX_sensitivity. Free-space path loss: FSPL = 20*log10(d) + 20*log10(f) - 147.55 dB. At 2.44 GHz: FSPL = 40 + 20*log10(d_meters). Set FSPL = LB to find max range. Indoor environments add 3-6 dB per wall penetration.

How does PHY affect range?

1M PHY sensitivity: -97 dBm. 2M PHY: -94 dBm (3 dB worse = 30% less range). Coded S=8: -103 dBm (6 dB better = 2x range vs 1M). Combined with higher TX power (+20 dBm in BLE 5.0), Coded PHY achieves 400+ m LOS.

Real-world vs theoretical?

Theoretical LOS with 0 dBm TX, 1M PHY: ~100 m. Real-world indoor: 30-50 m due to walls (3-6 dB each), furniture, body absorption (3-5 dB), and multipath fading (10-20 dB margin needed). Pocket/bag attenuation adds 5-10 dB. Design for 10-15 dB fade margin.

Wireless Protocols

BLE Range

BLE Range is determined by the link budget: TX power + antenna gains minus receiver sensitivity. With 0 dBm TX and 1M PHY (−97 dBm sensitivity), the link budget is 97 dB, yielding ~100 m LOS or 30-50 m indoors. BLE 5.0 Coded PHY (S=8) improves sensitivity to −103 dBm (+6 dB = 2× range), and the maximum TX power increase to +20 dBm enables links exceeding 400 m LOS.

Category: Wireless Protocols

Indoor: 30-50 m typical

LOS Max: 400+ m (Coded)

Understanding BLE Range

At 2.44 GHz, free-space path loss increases 6 dB per doubling of distance: FSPL = 40 + 20·log₁₀(d) dB, where d is in meters. Indoor environments add wall losses (3-6 dB each), body absorption (3-5 dB), and multipath fading. Engineers design for 10-15 dB fade margin to ensure reliability.

Antenna gain matters: a PCB trace antenna is typically −3 to 0 dBi. A small external antenna can provide +2 to +5 dBi, directly extending range. Orientation and ground plane effects can cause 10+ dB variation in real products.

BLE Link Budget

FSPL at 2.44 GHz:
FSPL = 40 + 20·log₁₀(d_m) dB

Max range (LOS, no margin):
d = 10^(LB−40)/20 meters
0 dBm TX, 1M: d = 10^(97−40)/20 = 70 m
+20 dBm TX, Coded S=8: d = 10^{(123−40)/20} = 1,400 m

Range by Configuration

Config	TX Power	PHY	LOS Range	Indoor
Basic	0 dBm	1M	~70 m	30-50 m
High power	+8 dBm	1M	~180 m	50-80 m
Long range	0 dBm	Coded S=8	~140 m	50-80 m
Max range	+20 dBm	Coded S=8	~1,400 m	100-200 m

Common Questions

Frequently Asked Questions

How is range calculated?

Link budget = TX + gains − sensitivity. FSPL at 2.44 GHz: 40 + 20·log₁₀(d). Set FSPL = LB to find max range. Add 3-6 dB per wall indoors.

PHY impact?

1M: −97 dBm. 2M: −94 dBm (30% less range). Coded S=8: −103 dBm (2× range). +20 dBm TX enables 400+ m.

Real vs theoretical?

Real indoor is 30-50% of LOS due to walls, body absorption, and fading. Design for 10-15 dB margin.

Related Terms

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