Can I use my old iPad charger to charge my new iPad

You haven’t provided any details of your iPad model - as such, a definitive answer is not necessarily straightforward.

With very limited exceptions, iPad requires a Power Adapter to be rated at a minimum of 10-12W to reliably charge. An iPhone 5W Power Adapter, if it works at all, will only charge an iPad very slowly.

Your new iPad (model?) has likely been supplied with a USB-C 20W Power Adapter and a USB-C to USB-C cable. Most iPads supplied with this Power Adapter support USB PD (Power Delivery) Fast Charging - and will charge at its maximum charging rate when using this (or higher rated) Power Adapter. When using USB PD, the maximum charging rate is 18W (i.e., 1.5A @12V / 2.0A @9V).

Older Power Adapters, with a standard USB Type-A connection, will charge the iPad at a slower rate. For example, a 12W Power Adapter can output 2.4A @5V.

Assuming that you new iPad has a USB-C connector (i.e., you have a 2020 iPad Air4 or 2018/2020/2021 iPad Pro), if you wish to connect to an older style Power Adapter, you will need a USB3 Type-A to USB-C cable. Here is an example marketed by Apple:

• mophie USB-A Cable with USB-C Connector (1 m)

https://store.apple.com/uk/xc/product/HN892ZM/A

If your iPad has a Lightning port, subject to the outlined minimum power requirements of iPad, you can use your existing Power Adapter and USB Type-A to Lightning cable to charge the iPad.

Thank you for the additional information.

Your iPad8 has a Lightning port. If the Power Adapter that you have with you (very likely having the older style USB Type-A connector) has the same connector as your charging cable, then you’ll be able to charge.

If instead the cable that you have with you is the newer (smaller) USB-C connector, you will need to replace the cable. The cable that you need is not the cable for which I have already provided a link - but is instead the older USB Type-A to Lightning cable:

• Lightning to USB Cable (1m)

https://store.apple.com/uk/xc/product/MXLY2ZM/A

yeah,though the old 5watt ipod touch or iphone ac chargers are a bit on the low current end so they charge rather slowly