Upgrading the resonators is the only way to increase the level of a portal. This is just one of the actions that you can do on the Portal Upgrade screen. Just like the deploy resonator action, there are similar rules for the upgrade resonator action:

Upgrade Resonator

Upgrade Resonator

Upgrade Resonator Requirements:

When you go to the upgrade portal screen and you need to deploy better resonators, there are a few requirements before you can proceed:

  • you need to fill every resonator slot – octant – before you can upgrade
  • you can only deploy resonators that are your level or lower
  • there is a limit to how many of each resonator you can deploy on one portal, it depends on the resonator level
  • you can only upgrade a resonator with a higher level one

Resonator Level Limit:

There is a  limit to how many resonators of each level you can deploy on one portal:

  • 8 x L1 Resonator
  • 4 x L2 Resonator
  • 4 x L3 Resonator
  • 4 x L4 Resonator
  • 2 x L5 Resonator
  • 2 x L6 Resonator
  • 1 x L7 Resonator
  • 1 x L8 Resonator

Screenshots:

[Photos of upgrade resonators]

Other Info:

At this screen you can swipe through the octants and see deployed resonators in them. If all the requirements are met, the Upgrade Resonator button will be active. Also when you get one resonator in view you will see its stats. It’s current and maximum energy level is displayed, cardinal position of resonator [S, SE, E, NE, N, NW, W, SW] as well the owner of that resonator. You can choose which resonator to upgrade, and for efficiency you should upgrade the lowest level resonator first. There are times when upgrading the most damaged resonator first can be more beneficial than picking the lowest level resonator.

When you click the upgrade option, all Resonators from your inventory will show up, and the lowest possible upgrade for the current resonator will be selected. Any possible resonator upgrades will be activated and the rest of the resonators you can’t use are shaded.

Best Practices:

The best tactic is to deploy your resonators as far from the portal as possible, because this makes it harder to hit them all in one XMP attack. To minimize portal damage, you should deploy your highest level resonators on opposite sides from each other so that one XMP blast will not damage them as much as it would if you deploy them in neighboring octants. Here is an example of how you should place Resonators if you are L6 Agent and you want to max the portal’s level: L6-L4-L5-L4-L6-L4-L5-L4 in this way your portal will have its highest level resonators evenly distributed in case of attack.
Some critical info: you can’t change the position of resonators when you upgrade them. The upgraded resonator will deploy to the exact same location as the already placed resonator. If someone deploys resonators in a bad position, you can at least upgrade them to give them some semblance of defense, or wait until they decay to deploy again. This again calls for teamwork, from upgrading portals to higher levels to teaching lower level agents how to deploy their resonators at the right distance.

AP Gain:

Since version 1.21.0 when you upgrade resonators you can gain AP, but only if you are upgrading someone else’s resonator. You can see resonator ownership in the resonator stats on the upgrade resonator screen. For every resonator upgrade you get +65 AP

XM Cost:

Just like the deploy cost for resonators, the same logic is applied with the upgrade process. The XM cost does not depend on the already placed resonator’s level, just the ones that you are deploying during the upgrade:

  • L1 Resonator 50 XM
  • L2 Resonator 100 XM
  • L3 Resonator 150 XM
  • L4 Resonator 200 XM
  • L5 Resonator 250 XM
  • L6 Resonator 300 XM
  • L7 Resonator 350 XM
  • L8 Resonator 400 XM