More than four million parcels have gone missing between April 2022 and April 2023, according to financial comparison site Finder.

Twelve per cent of people surveyed by Finder said their parcel was lost in transit; five per cent had a package stolen after it was delivered to their home; and four per cent of parcels were delivered to the wrong address.

Aussies lost out on items worth $129 on average with each missing package.

Finder money expert Rebecca Pike said it was a growing problem.

"On top of costing Aussies millions every year, it's also a pain in the neck to try to track it down," she said.

She said the theft of parcels was opportunistic amid the growing popularity of online shopping.

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"If you're not going to be home, it's worth making alternative arrangements for your deliveries," she said.

"Requesting a signature on delivery, installing a doorbell camera or leaving instructions for your courier to drop your delivery in a secure location can all help to minimise the risk of theft."

Delivery services offer options for people wanting to keep their parcel safe.

Rather than having a parcel sitting outside the front of a house, mail and packages can be sent directly to a local post office, PO box or a parcel locker.

Ensuring a parcel has one clear address and a return-to-sender could help prevent it getting lost.

An Australia Post spokesperson urged customers to notify police if they suspected their mail had been tampered with or stolen.

"Australia Post takes seriously its responsibility to deliver mail and parcels in its care and the vast majority of items make it to their destination safely," the spokesperson said.

"For any delivery service concerns, we encourage customers to contact us on 13 POST so that we can provide help and support."