Is an iPad Pro with iPadOS 15.6.1 too old to trade in?

Any iPad capable of update to iPadOS 15.6.1 is new enough to have a trade-in value with Apple.

Whatever its current value, the estimated trade-in value for your iPad will be considerably less than you paid for the iPad - and likely to be less than you might like.

You can obtain an estimate of the available trade-in value here:

Apple Trade In - Apple

Be aware that your iPad can be updated to the most recent version of iPadOS - this being iPadOS 15.7.1, or possibly iPadOS 16.1.1.

iPadOS 16.1.1 is available for these models of iPad:

• iPad Pro (all models)
• iPad Air (3rd generation and later)
• iPad (5th generation and later)
• iPad mini (5th generation and later)

You can see for yourself here:

Apple Trade In - Apple