Power Budget Calculator
Add up every gain and loss between an access point and a client to find the signal each end receives, the margin left, and whether the link is balanced in both directions.
How to use this tool controls and what to look for
Set up an access point, a client and the path between them, and see the signal each end receives and the margin left.
Controls to change
- Full: AP ↔ client: work out both directions. Simple: transmitter → receiver works out one direction only.
- Indoor AP: start from the Indoor AP, Low power AP or Outdoor AP preset, and a Phone, Laptop or IoT sensor for the client.
- Transmit power: change the power at either end, along with Antenna gain and Cable and connector loss.
- Distance: set how far apart the two ends are.
- Walls and other losses: pick Plasterboard walls, a Brick wall or a Concrete wall, or type your own loss.
- Required signal: choose −67 dBm for voice and video, −70 dBm for data, or lower for basic coverage.
What to look for
- The uplink (client to AP) is usually weaker, because the client transmits with less power than the AP.
- Turning up AP power only helps the downlink. If the uplink misses the target, the link is still unbalanced.
- Watch the margin. Plenty of margin leaves room for people, furniture and fading. "Little headroom" means one extra wall could break the link.
About this tool
A power budget adds up every gain and loss between an access point and a client to find the signal each end receives and how much margin is left. This calculator works out both directions, AP to client and client to AP, so you can see when a strong AP is heard by a client that can't be heard back.
What you'll learn
- How EIRP is worked out: transmit power + antenna gain − cable loss
- How path loss, walls and receive antenna gain give the received signal
- Why the uplink, from client to AP, is usually the weaker direction
- How to choose a required signal level and check the margin
Common questions
What is EIRP?
Effective isotropic radiated power: the transmitter's power plus antenna gain, minus cable and connector losses. Regulators set limits on EIRP.
Why can a device see the AP but not connect?
Often the link is unbalanced: the AP transmits more power than the client, so the client hears the AP but the AP can't hear the client.
How much margin should a Wi-Fi link have?
A common rule of thumb is 10 dB or more above the minimum signal you need, to allow for fading, people moving and doors closing.
Free for private and educational use. This interactive model is a simplified teaching aid and may contain mistakes. It is provided as is, without warranty. Use it to understand the concepts, not as a substitute for a site survey, vendor documentation or professional design advice.