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# Free-Space Path Loss (wavelength)

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Equation / Last modified by KurtHeckman on 2018/08/15 19:10
`FSPL = `

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DavidC.Free-Space Path Loss (wavelength)

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9e92fdcd-0e12-11e3-8615-bc764e049c3d

The **Free-space Path Loss (FSPL)** calculator computes the loss of signal strength on a line-of-sight path which has no obstacles or other disturbances based on the distance (**d**) and the wavelength (**λ**) of the signal.

**INSTRUCTIONS:** Choose the preferred units and enter the following:

- (
**d**) This is the distance between receivers. - (
**λ**) This is the wavelength of the signal.

**Free-Space Path Loss:** The calculator returns the loss in dB. However, this can be automatically converted to a real or percent via the pull-down menu.

##### Related Calculators

- Free-Space Path Loss (wavelength)
- Free-Space Path Loss (using frequency)
- Fiber Optic Cable dB Loss Budget Calculator:
- Compute Frequency from Wavelength
- Compute Wavelength from Frequency

#### General Information

The formula for the Free-Space Path Loss based on wavelength used in this calculator is:

FSPL = ` ((4 pi * d*f)/λ)^2`

where:

- FSPL is the Free-space path loss
- d is the distance between receivers.
- λ is the wavelength of the signal.

This equation is only accurate at a distance from the transmitter where spherical spreading can be assumed. This equation is not accurate for short distances.