The busier the food court, the cheaper your Big Mac.

People are paying less for their McDonald's at busy areas compared to stand alone suburb stores.

A Big Mac is 45 cents cheaper at Westfield Parramatta in Sydney compared to the most expensive store at Wiley Park in the city's south-west for $5.85.

7 News Sydney discovered the price discrepancy when they bought half a dozen items at six McDonald's locations across metropolitan Sydney.

Big Macs are cheaper in busy locations such as food courts where competition in high.

'I think people would be shocked because I think we all think a Big Mac is a Big Mac,' said Steve Kulmar of Retail Oasis consultancy group.

Only a few McDonald's items have national pricing like the $2 range.

The total of the items 7 News bought varied by up to $1.60, with Wiley Park being the most expensive overall.

Mr Kulmar said he was not surprised Westfield Parramatta was the cheapest. 

'There's a lot of competition in that food court so you'd expect that price to be really sharp,' he said.

People looking for the cheapest products should go where there is a lot of competition in the food court and try middle class suburbs and busy locations.

Other fast-food chains including KFC, Dominos and Hungry Jack's also have price variations.

The McDonald's at Westfield Parramatta is one of the cheapest in Sydney, a 7 News Sydney investigation found.

Some people defended the price difference on Facebook, saying costs can vary due to local delivery costs, staff wages and rental locations.

Others were frustrated with the situation, with one saying that's why they love Parramatta.

'But seriously this is disgraceful, why should people in different areas pay different for the same product?' they said.

A Daily Telegraph survey of McDonald’s stores across NSW last year revealed a coffee could up to 19 per cent more expensive in the outlet just a few suburbs over.

The cheapest regular-sized coffee was found at Chatswood for $3.95, while out west in Granville and Emu Plains a cuppa cost $4.70.

But in the same suburb prices could vary as well, with a cappuccino from Bondi Beach costing 50 cents more than one from Bondi Junction, and one from Penrith North costing 35c more than one from Penrith Plaza.