Link Budget Calculator
Estimate EIRP, maximum path loss and cell range using Free-Space Path Loss (FSPL) model.
Range uses FSPL only — no terrain or clutter correction. Use the Path Loss tool for Okumura-Hata estimates.
3GPP · ITU-R · Okumura-Hata · COST-231
Link Budget Formulas
A link budget accounts for every gain and loss between transmitter and receiver to determine whether a radio link is viable.
EIRP = PTX + GTX − LTX
MAPL = EIRP − SRX + GRX − LRX − Mshadowing − Minterference
FSPL = 20·log₁₀(dkm) + 20·log₁₀(fMHz) + 32.44 [dB]
dkm = 10 ^ ((MAPL − 20·log₁₀(f) − 32.44) / 20)
EIRP = Effective Isotropic Radiated Power · MAPL = Maximum Allowable Path Loss · SRX = RX sensitivity · M = margin
Frequently Asked Questions
What is EIRP?▾
EIRP (Effective Isotropic Radiated Power) is the total power that an antenna would need to radiate isotropically (in all directions equally) to produce the same signal strength in the main beam direction. It equals transmitter power plus antenna gain minus cable and connector losses. EIRP determines how strong your signal appears to a receiver.
What is MAPL?▾
MAPL (Maximum Allowable Path Loss) is the largest propagation loss the radio link can tolerate while still meeting the minimum required signal level at the receiver. It is calculated as EIRP minus RX sensitivity plus RX antenna gain, minus all fade and interference margins. Higher MAPL means longer potential range.
Why is the FSPL-based cell range unrealistically large?▾
Free-Space Path Loss assumes a clear line of sight with no obstructions — ideal for satellite links but not urban ground-level cells. Real deployments add 20–40 dB of excess loss from buildings, terrain, and vegetation. Use the Path Loss tool with Okumura-Hata for realistic terrestrial range estimates.
What is a typical LTE macro link budget?▾
A typical 1800 MHz LTE macro downlink budget: TX power 43 dBm + antenna gain 18 dBi − cable loss 2 dB = EIRP 59 dBm. RX sensitivity −100 dBm + RX gain 0 dBi − shadowing 8 dB − interference 3 dB gives MAPL ≈ 148 dB. With Okumura-Hata urban corrections this corresponds to roughly 2–4 km cell radius.