Here is a link to a handy online tool I have used over the last few elections to determine how much hope or threat there is in a close election. Bookmark it for use as the returns roll in.

A common scenario is that your candidate is down by a few points, with some of the vote still not counted. The key question is how much of the remaining vote your candidate needs to get in order to finish “first past the post.” If the “remaining vote” number gets unreasonably high, as it did far too early in key states in the Clinton/Trump race, you will know whether to make it an early night. If the number still looks achievable, then you will want to hang in for some better data.

In the case above, my candidate is trailing with 45% of the votes cast, but only 30% of the vote is in. In this case, there are no third-party candidates, so the percentage needed to win is 50% plus one. We need, then, to get 52.14% of the remaining votes in order to end up with 50% of the total vote. As more of the vote comes in this number begins to rise precipitously:

Our odds are much better if we are tracking at 49%, but once we pass 90% of the votes counted the win still quickly tracks out of reach:

You can also use the tool to determine the safety of your margin if you are currently ahead. If your candidate currently has 52% of the vote, and 80% of the vote is in, he or she needs only 42% of the outstanding votes to still win.

If there are third party candidates, you can take the percentage needed to win down by half of the effect of the total third-party vote percentage (e.g., if third-parties are getting 2% of the vote, then you can probably win with just over 49% of the vote).

Note also that some state constitutional referenda, such as in Florida, require a 60% plus one vote in order to pass, so just change the “percentage-to-win” value to 60 for these ballot issues. And some state elections, such as Georgia’s governor race, require 50% of the vote plus one to avoid a run-off election.

Happy counting and good luck!