The choice is regulatory first and technical second: 868 MHz for Europe, 915 MHz for North America and Australia, 470 MHz for China, 433 MHz where ITU Region 1 permits it. Propagation differences inside 433-928 MHz are small compared with duty cycle and EIRP limits.
The physics gap between 433 and 915 MHz is real but modest. Free-space path loss at 1 km:
| Frequency | FSPL @ 100 m | FSPL @ 1 km | FSPL @ 5 km |
|---|---|---|---|
| 433 MHz | 65.2 dB | 85.2 dB | 99.2 dB |
| 868 MHz | 71.2 dB | 91.2 dB | 105.2 dB |
| 915 MHz | 71.7 dB | 91.7 dB | 105.7 dB |
433 MHz has about 6 dB less path loss than 868/915 MHz — real, and worth roughly a doubling of range in free space. But three other effects usually dominate:
1. Obstruction and diffraction. Lower frequencies diffract around edges and penetrate walls and foliage better. In dense indoor or industrial deployments this advantage can exceed the pure FSPL difference. 2. Antenna size. A quarter-wave element is about 17 cm at 433 MHz and 8 cm at 868 MHz. In a compact device, the higher frequency antenna is often easier to fit efficiently — which can cancel the propagation advantage. 3. Noise and congestion. 433 MHz is a narrow, crowded allocation with many legacy garage-door, TPMS and remote-control users. 868 MHz is wider and structured into sub-bands with defined duty cycles. A quiet band beats a quieter frequency.
Bottom line: do not choose 433 MHz for the range. Choose it only if your market allows it and your bandwidth needs fit within 1.74 MHz of spectrum.
| Band | Spectrum available | Power | Duty cycle | What it means for you |
|---|---|---|---|---|
| 433 MHz | 1.74 MHz (433.05–434.79) | 10 mW ERP (≈12 dBm EIRP) in Europe | ≤10 %, or LBT+AFA | Low power, narrow band. Fine for sparse telemetry, weak for dense networks |
| 868 MHz (EU) | 7 MHz (863–870), structured sub-bands | 14 dBm ERP (25 mW) typical; 500 mW in 869.4–869.65 MHz | 0.1 %–10 % by sub-band | Downlink capacity is the constraint; gateways are duty-cycle limited too |
| 915 MHz (US) | 26 MHz (902–928) | 1 W conducted + up to 6 dBi antenna | None; ≤0.4 s dwell per channel for hoppers | The most permissive regime; longest practical range |
| 470 MHz (CN) | 40 MHz (470–510) | 50 mW ERP | LBT mandatory, ≤1 s per transmission, one channel at a time | Designed for metering; LBT is not optional or disableable |
Two consequences buyers underestimate:
Sometimes — but read the fine print.
| Antenna claim | Realistic coverage | Caveat |
|---|---|---|
| "433 MHz antenna" | 433 MHz only | Will not cover 470 MHz well, and definitely not 868/915 |
| "868/915 MHz antenna" | 863–928 MHz | The honest and most common wide sub-GHz part |
| "433/868/915 MHz" | Usually 863–928 MHz well, 433 MHz poorly | More than an octave of span; verify with a VSWR plot per band |
| "315–915 MHz" | Widest claim; verify each band | Efficiency at the extremes is typically much lower than mid-band |
Ask for VSWR and efficiency plots for each band separately, not one sweep across the whole range. A part that reads 1.8:1 at 868 MHz and 3.5:1 at 433 MHz is not a 433 MHz antenna, whatever the label says. If you genuinely need 433 and 868/915 in one product, two antenna options or a deliberate wideband design is the honest answer.
| Your situation | Choose |
|---|---|
| EU-only sensor, moderate data rate | 868 MHz, 2–3 dBi omni, keep the feeder short |
| US-only sensor, long range | 915 MHz, up to 5–8 dBi on a fixed node (watch EIRP) |
| China metering | 470 MHz explicitly — a 433 MHz antenna will not do |
| Global SKU, one hardware build | 863–928 MHz antenna + regional firmware; accept a compromise, or fit two variants |
| Very compact device | Higher frequency is easier: 868/915 MHz fits a shorter element more efficiently |
| Dense urban deployment | 868/915 MHz with good gateway density beats 433 MHz with a noisy band |
1. Buying "433 MHz" for China. China's LoRa metering band is 470–510 MHz. Different antenna. 2. Assuming 433 MHz works in North America. It is an ITU Region 1 allocation; US deployments face a different authorisation path entirely. 3. Over-gaining to fix coverage. In the US a higher-gain antenna raises EIRP; in Europe it does not help against a duty-cycle limit. Fix placement and feeder length first. 4. Ignoring the gateway's duty cycle. EU868 downlinks are the scarce resource, not uplinks. 5. One wideband antenna for everything. Convenient for purchasing, costly in efficiency.
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Regulatory limits vary by country and change over time. Values reflect the cited standards as of October 2026; confirm with your local regulator before deployment.
Contact: Mr.Li
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