WiFi Range Calculator
Free space WiFi loss from band and meters.
What it does
Radio fades with distance and frequency even in empty space. Free space path loss turns meters and megahertz into decibels so link budgets add in one unit. Doubling distance costs about 6 dB, and moving from 2.4 to 5 GHz costs about 6 dB at fixed range.
The tool above runs the Friis free space line. At 2400 MHz and 30 m, loss is 69.6 dB against 40 dB at 1 m, or 29.5 dB past the reference. At 5000 MHz and 15 m, loss is 69.9 dB against 46.4 dB at 1 m. Higher bands start higher at 1 m but distance still rules.
Indoor reality adds walls, people, and multipath on top. Drywall, glass, and concrete each take their own bite, while antennas shape gain by direction. That is why two identical routers disagree across rooms: free space sets the floor, obstacles set the bill.
This page models free space with isotropic antennas. It does not plan channels, pick transmit power, or certify coverage. Use it to compare bands and distances before a site survey.
How to use
- Enter the frequency in MHz.
- Enter the distance in meters.
- Read total loss first.
- Read the 1 m reference for the band.
- Read extra loss past 1 m.
- Add walls and margins for indoor planning.
Formula
- f
- Carrier frequency in MHz, such as 2400, 5000, or 6000.
- d
- Separation in meters, converted to km inside.
- extra
- Loss growth past the 1 m reference for the same band.
Free space path loss with isotropic antennas and clear line of sight. At 1 m the formula gives the reference loss for the band. Obstructions, multipath, and antenna patterns sit outside this line.
Worked example
Example: 2400 MHz at 30 m
Defaults: 2400 MHz at 30 m in free space. Walls, people, and antennas add more loss.
- Inputs: 2400 MHz at 30 m.
- Convert: 30 m is 0.03 km.
- Loss: 20 log 0.03 plus 20 log 2400 plus 32.44 is 69.6 dB loss.
- Reference: at 1 m the same math gives 40 dB at 1 m.
- Extra: 69.6 minus 40 is 29.5 dB past 1 m. Tool shows the same.
Reference table
| Band and distance | Loss | Past 1 m |
|---|---|---|
| 2400 MHz at 30 m | 69.6 dB loss | 29.5 dB past 1 m |
| 5000 MHz at 15 m | 69.9 dB loss | 23.5 dB past 1 m |
| 6000 MHz at 10 m | 68 dB loss | 20 dB past 1 m |
| 2400 MHz at 1 m | 40 dB loss | 0 dB past 1 m |
| 2400 MHz at 100 m | 80 dB loss | 40 dB past 1 m |
Limits
- Free space only. Walls and people excluded.
- Isotropic antennas. Real patterns differ.
- Line of sight assumed. Multipath ignored.
- No power or sensitivity. Budget needs those.
Common mistakes
- Mixing km with meters in the constant.
- Using GHz as MHz, off by 60 dB.
- Reading loss as signal bars.
- Ignoring walls in indoor plans.
- Comparing bands at different distances as if equal.
Try it yourself
Quick checks. Answers sit tucked under each question.
5000 MHz at 15 m?
Loss is 69.9 dB with 46.4 dB at 1 m, or 23.5 dB past 1 m.
6000 MHz at 10 m?
Loss is 68 dB with 48 dB at 1 m, or 20 dB past 1 m.
Questions
What is the free space formula?
FSPL = 20 log d_km plus 20 log f_MHz plus 32.44. Here 69.6 dB loss.
How fast does loss grow with distance?
About 6 dB per doubling in free space. Distance dominates the budget.
Does 5 GHz lose more than 2.4?
Higher frequency means higher loss at fixed distance. Here 5000 MHz at 15 m gives 69.9 dB.
Is this my router signal?
No. This is free space only. Walls, glass, people, and antennas shift real loss a lot.
Which units does the constant need?
Use meters for d and MHz for f with the 32.44 constant. Mixed units need conversion first.
How do I get range from loss?
Add transmit power and antenna gains, subtract this loss and margins. Link budget decides range.