Bettina Bammer-Whitacker, bottom center, eats dinner with Nathan Wieand, bottom right, at Toki Underground on Wednesday January 11, 2012 in Washington, DC. (Matt McClain/FOR THE WASHINGTON POST)

Just as Washington’s largest restaurants have opened in the past few years, so, too, have its tiniest. As with their gargantuan cousins, size presents problems for small restaurants. Namely, getting through the door: Because a small restaurant needs to keep every seat full to make money, many, like the 27-seat Toki Underground or the 28-seat Little Serow, take limited or no reservations.

The often longer-than-two-hour waits for a table (many of which take place at nearby bars, as diners await a text or call from the restaurant saying a table is open) are just part of the experience.

“A lot more thought goes into seating,” said Joe Ostrosky, general manager of Toki Underground, who does some mental math to guesstimate the wait time, which is usually one hour for every 27 people on the list.

Even smaller restaurants keep seats filled by going reservations-only, with penalties for those who flake out at the last minute. Jose Andres’s pricey Minibar, which seats 12, requires guests to leave a credit card number to make a reservation. To discourage no-shows, tickets to Seasonal Pantry’s 12-seat Supper Club must be purchased ahead of time. Chez Le Commis chef Tom Madrecki said he is able to replace no-shows for his 12- to 15-seat pop-up restaurant, held in his Arlington apartment, with guests on his extensive wait list, but will ask last-minute no-shows to at least cover the cost of their ingredients.

“It’s very rare that we get a no-show these days,” he wrote in an e-mail, “because people had to get lucky [and] respond ASAP to get their seats in the first place.”

Staffing also can be difficult in small restaurants. Even though Toki Underground has just 27 seats, it has 20 people on staff, with about 10 working any given night.

“For as many staff as we have, our labor costs are a little higher, but that’s because we want to provide a high level of service,” Ostrosky said.

In addition, a play on the old adage about too many cooks comes to mind.

“You’ve got five guys squeezing into our tiny kitchen,” Ostrosky said. “It’s close quarters.”