The cost to businesses in Birmingham following Saturday night's security alert could be in excess of £1m, according to the Chamber of Commerce.
Hundreds of people spent the night at Aston University
About 20,000 people were evacuated from pubs, restaurants and clubs in the city centre and a number of controlled explosions were carried out.
West Midlands Police took the decision after what they said was a "credible threat to lives".
The Chamber of Commerce said it was hard to put a figure on lost trade.
Spokesman John Lamb told BBC News: "Around 20,000 people were evacuated from the city centre and who knows what they would have been spending, but the average figure for hotels, restaurants, pubs and clubs would have been around £30 to £40 a head.
"It was a very difficult situation for the police. Only they know why the decision was made and we have to trust that was made with all due respect to businesses and people in the city."
As the city centre returned to normal on Monday morning, some businesses said the police acted properly when they evacuated revellers on Saturday night.
Gary Taylor, chairman of Broad Street Partnership, said he had full confidence in the authorities.
Chief Constable of West Midlands Police, Paul Scott Lee, declined to describe the nature of Saturday's threat but said intelligence indicated it was genuine.
He said the decision to evacuate people from the city centre had not been taken lightly and came after a "very specific threat".
The company responsible for promoting the city said it believed the incident would have an impact on tourism.
Tim Manson, operations and policy director at Marketing Birmingham, said: "Birmingham will see a down-turn in visitors as any other city in the world will probably be experiencing now.
"But I think like other cities, it will see a bounce-back. The British people particularly are extremely resilient and the British are Birmingham's main visitors."