If there's one thing that's become clear about the Gulf oil spill, it's that nothing is clear. No one is sure how to plug the leak, where the oil will go next, where the oil is now, how dispersants have affected it, how hurricanes might affect it, how it affects wildlife, or even how it affects human health. But amid all this uncertainty, one sketchy statistic has loomed largest: How big is the spill?

BP executives and government scientists first estimated that about 210,000 gallons were leaking out every day, but weeks later, that number was revised to 420,000. And as weeks have passed and multiple containment efforts failed, the leak's estimated size has only continued to grow. After updating their estimate in late May to between 500,000 and 800,000 gallons, officials then doubled it a few weeks later, pushing the range well beyond 1 million gallons a day. The most recent revision, issued by the federal Flow Rate Technical Group on June 15, raises the range as high as 2.5 million gallons daily; if that's accurate, enough oil is spilling into the Gulf to re-create the 1989 Exxon Valdez oil spill every five days.

But despite such unclear and sometimes conflicting reports, Americans have nonetheless strived to grasp the scope of the ongoing disaster as much as possible. Estimating the spill's exact size is an inexact science, but doing so can at least help put the crisis in perspective and help people guess what to expect next. PBS produced a popular widget in May that tracks the spill's size using a range of estimated flow rates (and it includes a live video feed from the mile-deep spill site), and several others have followed suit.

To offer a more compact, streamlined spill counter on MNN's homepage, we created a widget that uses a single, middle-of-the-road figure rather than a full range. Taking the most recent government estimate that between 1.5 million and 2.5 million gallons are leaking every day, we used the midpoint of 2 million gallons as our daily rate of change. But since the flow rate grew larger in early June when BP engineers cut a riser pipe from the damaged well — part of their broader plan to fit on a containment cap — we only applied the 2 million-gallons-a-day rate since June 3, when the pipe was cut. For the 42 days before that, we apply a daily change rate of 1.6 million gallons, which is 20 percent smaller than the current estimate. As of June 15, when the latest estimate was released, that would mean the well has already gushed more than 98 million gallons since April 22. As the spill keeps growing and the numbers keep changing, we will periodically update this calculation to reflect the most recent assessment.

Check out the widget below and at MNN.com, and please let us know if you have any feedback in the comments. And make sure to visit our Gulf oil spill home page to stay on top of all the latest news on the disaster.