A quick trip to the loo left an Auckland woman an instant millionaire after discovering the Lotto ticket she had been carrying in her wallet for three weeks had scooped $1 million.

The woman, who wished to remain anonymous, bought her ticket while out running errands – then put the ticket in her wallet and forgot about it.

Three weeks went by before she remembered the ticket, and decided to check it while on a work break.

"As I headed to the loo, I remembered I had a ticket to check. I'd completely forgotten about it until then, but figured I might as well check it since I was in the area – who knows how long I would have left it otherwise," she laughed.

Unbeknownst to her, the little yellow piece of paper she had been carrying around for three weeks was worth $1 million.

"The lady at the Lotto counter checked my ticket and told me how much I had won – I just didn't believe her.

"She offered me a chair to sit down in and let the news sink in, but I just kept thinking how I needed to get back to work."

Now a millionaire, the woman had to keep a straight face as she headed back to work with her exciting news on her mind.

"I managed to finish the rest of my day at work without spilling the beans to anyone. But as soon as I got home I told the kids and called my parents to let them know the good news – they were so excited, we're all absolutely thrilled."

As for why it took the woman so long to check her ticket and claim her prize, it was all down to blissful ignorance.

"I didn't know that a winning ticket had been sold at Paper Plus Howick, let alone that it was an unclaimed $1 million ticket.

"Everything happened by absolute chance – from the moment I bought the ticket, right through to when I checked it. I feel very lucky."

With the money now safely in her bank account, the winner is still letting it sink in and is taking her time deciding how she might spend her windfall.

"I'm looking forward to helping my children out and buying a new car," she said.

"Winning Lotto is so surreal, you're constantly pinching yourself. You never think it'll happen to you…until it does."

The winning Lotto ticket was sold at Paper Plus in Howick for the July 18 draw.