Motorists know how many miles they get to a gallon. Fliers know their airlines' on-time arrival percentage. Consumers are told how many calories there are in a Big Mac.

But when it comes to online services, users have no idea about the capacity of the service. And as we have learned from America Online, if it's too popular, you could be in trouble.

It is no help knowing that at AOL 8 million subscribers are being served. We need to know how many users AOL can serve at one time-which is a lot less than 8 million. And since each region has its own connection points, we need to know that on a regional basis as well.

Service providers always risk growing too popular for the number of customers they can support. It is just that here the scale is much bigger and the situation more drastic as the world's largest online provider made the sudden jump from a metered a la carte service to an all-you-can-eat service.

It is as if McDonald's suddenly became an all-you-can eat operation and whole families, accustomed to rationing their burgers, stormed their local outlets to sit around all day and wolf down Big Macs. You could hardly blame McDonald's for its popularity, but it does have a new level of responsibility: Customers need to know if they will get access to the buffet table and whether there are enough burgers to go around.

Fortunately, some 38 state attorneys general have pressured AOL into giving dissatisfied customers refunds and halting AOL's marketing efforts until the situation improves. But to stop at that is no more than a knee-jerk reaction to the public's frustrations.

FULL DISCLOSURE

The real fix for so-called "deceptive sales practices" is for online services like America Online to reveal just how many customers using their system at one time they can support and what is the average "time to connect" at peak times in a given region.

The simplest measure is the ratio of modems or user inputs available to users.

The question is, who is going to make the industry reveal this information? If it is smart, the companies will do it themselves-either as a combined effort by an online industry trade group or as a competitive ploy by a service provider looking to win real points with the public.

If the industry are not smart, it will simply be providing the Federal Trade Commission or an ambitious legislator with a modicum of modem awareness with an historic opportunity to make a name for themselves on the info highway.

Online services have induced the public to rely upon them and therefore the public has a right to know what can be relied on.

As our dependency grows, so will our need for better labeling.

The problem for this industry is people have come to expect instantaneous connections from the phone companies and, for that matter, cable TV; and the less like cable or telephones online services are, the more explaining they will have to do.

The growth of the Internet is so explosive that not only AOL but dozens of smaller service providers risk this happening again. If it does, the slogan of the Internet will be something like, "8 million burned."

Mr. Brody is president of Techmarketing, Scarsdale, N.Y. Paul Goodman is a partner in the New York law firm Elias Goodman Shanks & Zismore.