Wireless Link-Budget Calculator

Calculate a rough estimate, with our handy tool


The Link-Budget information supplied in this document is designed to provide an extremely-rough estimate of expected wireless range. In the real world, you may receive more or less effective range, depending on several additional factors. This calculator is most useful for gaining an understanding of how signal is affected by obstacles and free-distance, rather than to provide a predication of the exact range you should expect from a wireless product.


A Link-Budget is the total amount of power between a transmitter and receiver. By taking this Link-Budget and factoring in the loss of power through free-space and other obstacles such as walls, it’s possible to roughly estimate the effective transmission distance and to gain an understanding of how various obstacles and other changes affect a signal. Of course, wireless signal strength calculations aren’t really so simple, factors such as antenna directionality, design efficiency, reflection, scattering, diffraction and weather conditions all play a significant role.

The below calculator will provide an extremely-rough estimate of signal strength based on free-space proportion and obstacles only, but can be incredibly useful in helping to understand the affect various obstacles will have on the range of a wireless product.


Estimated Distance = N/A

The Real-World

Example 1 – LM540 Bluetooth 2.1 EDR + 2dBi Antenna (SPP) x 2 at Olympic Rowing Lake (Dorney Lake)

Confident in the capabilities of our LM540 USB-powered Bluetooth 2.1 EDR Adapter, LM Technologies set-off to prove its adapters in a real-world scenario by utilising the long straight at Dorney Lake, which provides Olympic-class distance measurements. A Pair of LM540 adapters, both equipped with 2dBi antennas, achieved a distance of 787M (murky weather, no rain). In this test, there were no notable obstacles and the adapters and their respective laptops were held at around waist height.

Note: Achievable bit-rate will gradually reduce over the transmission range.

Example 2 – CSR101x Compact Reference Design Bluetooth 4.0 SMART (Low-Energy)

reference ble moduleUtilising a reference design compact module equipped with a CSR101x Bluetooth SMART (Low-Energy) IC, chip vendor CSR was able to achieve between 30 and 50M range in open-space, when limiting transmission power on the chip to 0dBm.

These modules typically feature a sensitivity of -92.5dBm with dynamically adjustable transmission strengths, ranging up to 9dBm.

Note: Compact modules with onboard antennas feature additional design challenges when compared with their big brothers. Noise from other components can play a greater role and the smaller effective ground plane of a miniaturised module can reduce performance.