Borussia Dortmund CEO Hans-Joachim Waztke revealed Thursday that each home game held without fans costs the Bundesliga club €4 million ($4.7 million) in lost revenue.
Dortmund's Signal Iduna Park is the biggest stadium in Germany and can host 81,000 spectators.
Fans are currently locked out of all Bundesliga matches as part of government measures to restrict the spread of the coronavirus.
Last season's Bundesliga runners-up closed the 2019/20 financial year with a loss of €44 million after last season was disrupted by Covid-19.
In Thursday's annual general meeting, held online because of the pandemic, Watzke said he fears losses of up to €75 million this season.
However, the Dortmund boss gave assurances that the club has "sufficient liquidity to ensure that there is no danger" to their existence.
As well as revealing the scale of lost revenue for each home game, Watzke said salary waivers for their squad and club employees has saved around €11 million.
Dortmund start the weekend third in the Bundesliga table having lost 3-2 at home to leader Bayern Munich before the international break.