As always there is a big differential as to location and rent. That aside though : Yes rent can be a killer, the lease can have a lot of effect on a restaurant

As always there is a big differential as to location and rent. That aside though : Yes rent can be a killer, the lease can have a lot of effect on a restaurant, I'd say more so than any other business. As for the biggest cost? Assuming the owner doesn't try to rent a bad location(eg high competition with long term customer base), I would say it is staffing. But that is a double edged blade. Hiring top quality may be necessary where you are located, or may break the businesses back, if in a different location. Hospitality is such a locale based business there isn't a specific rule that can cover everything. A lot of people will look at their food costs as the biggest cost, (and it can be if not managed properly), but I have seen more businesses fail from bad staff management than anything else. This isn't to say it's an easy thing to control though, you are talking about an industry where you won't actually know the number of covers within a large percentile from day to day. (yes you can estimate, but a table of 30 walk-ins without reservation isn't as rare as you would think).