There is a moment, just before you pass your old handset to its new owner, when rushing costs you. Most people assume a quick reset wipes the slate clean, but that is not always the case: a phone erased in the wrong order can stay locked and useless for whoever buys it, or leave behind personal data you thought had gone for good. Selling a used phone well is really a matter of order, not speed.

Before you tap Erase: back up, move your codes and note the IMEI

Start by protecting what you want to keep. Run a full backup and wait for it to actually finish, because a photo library running to dozens of gigabytes takes time and a steady connection.

Next, deal with two-factor authentication. If your login codes arrive through an authenticator app on the very phone you are selling, a factory reset can shut you out of your own accounts, banking included. In Google Authenticator, open Menu, Transfer accounts, Export accounts and move them to your new handset before you erase anything.

Finally, jot down the IMEI and the battery health, as you will need both for the listing.

The step everyone forgets: sign the account out before you reset

This is where the most common mistake happens. On an iPhone, once Find My is switched on, Activation Lock ties the handset to your Apple Account, so if you sell it without signing out of iCloud the buyer will not be able to set it up. Android works on the same principle through Factory Reset Protection: if your Google account is still on the device, the phone will demand those details again after the reset and become unusable for the next owner. Signing out is not enough; the account has to be removed.

  • Sign out of your accounts first (iCloud or Google) so the handset unlocks for the buyer.
  • Reset from the settings menu while you are still signed in, not from recovery mode.
  • Do not just delete your apps and sign out: Activation Lock and Factory Reset Protection stay put.
  • Do not sell an iPhone with Find My still tied to your account, or it will stick on the activation screen.

Watch out: always reset from the settings menu with the phone online. A wipe started from recovery mode leaves Activation Lock in place.

The factory reset, step by step

Only now does it make sense to wipe everything. Google advises charging to at least 70% battery before you begin, and knowing your credentials in advance. The reassurance comes from encryption: the storage is encrypted at all times and the wipe destroys the keys, which leaves the files unreadable. Recovery remains possible only in the theory of a specialist lab, a scenario that has no bearing on a private sale.

On an iPhone

  1. Sign out of iCloud from Settings, [your name], Sign Out, which turns off Find My and Activation Lock.
  2. Start the wipe from Settings, General, Transfer or Reset iPhone, Erase All Content and Settings.
  3. Enter your Apple Account password when prompted, with the phone online so it can reach Apple's servers.
  4. Pop out the SIM and check the handset reboots to the welcome screen.

On Android

  1. Remove your Google account from Settings, Passwords and accounts, your account, Remove account.
  2. Open the reset options from Settings, System, Reset options, Erase all data.
  3. Confirm with at least 70% battery and wait for the full reboot.
  4. Take out the SIM and any microSD and check it restarts to the initial setup.

What a reset leaves behind: SIM, eSIM and open sessions

A reset does not touch everything, and this is exactly where stray data slips through.

Does a factory reset erase this?
What is on the phone Wiped by the reset?
Photos, apps and accounts stored on the phone Yes, for good
Physical SIM No, take it out yourself
eSIM No, sort it with your provider
microSD card No, remove or reformat it
Active cloud sessions No, sign out from a browser

Pop out the physical SIM with the eject tool and keep it, as it holds your line and some contacts. If you use an eSIM, do not delete it until you have arranged to move your number to your next handset or provider, or you risk losing it. Any microSD card survives the reset and has to be removed or formatted separately through the storage settings.

One last, often skipped step: from a web browser, remove the phone from your account's list of devices on Google or Apple. That closes any sessions still open and drops it from your trusted devices for two-factor authentication.

Selling for the right price: IMEI and battery health

Two details decide how well your listing does. The IMEI is the unique 15-digit code you get by dialling *#06#: buyers check it against stolen-device databases, and a blacklisted phone will no longer work on the networks. State the battery health too, since it weighs heavily on the price. If you would rather not resell at all, a recycling or trade-in route is worth a look, and it is a good moment to see what an eSIM or a refurbished handset could offer for your next upgrade.