Happily, today’s mortgage interest rates appear a little lower than they were this time last week. But with so much economic uncertainty, it’s anyone’s guess where rates will head in a month or a year.

According to Bankrate, the average rate for a 30-year fixed mortgage today is 6.16 percent compared to 6.3 percent last week. While hovering above 6 percent counts as a historically low rate, it’s a bit higher than rates landed by a lot of buyers in recent years. And let’s not forget that just two weeks ago, the AP reported an average rate of 6.42 percent for 30-year mortgages.

The possibility of northward rate movement is one of the main factors in the "buy now" argument made by agents and mortgage brokers. But how much more would you pay each month, if rates increased?

I used a mortgage calculator at Bankrate to figure the monthly payment on a $300,000 mortgage and the total interest paid with rates ranging from 5.75 percent to 8 percent.

Here’s what it looks like:

5.75 percent
Payment: $1750.72
Total Interest: $330,258.68

6.0 percent
Payment: $1798.65
Total Interest: $347,514.57

6.25 percent
Payment: $1847.15
Total Interest: $364,974.58

6.5 percent
Payment: $1896.20
Total Interest: $382,633.47

6.75 percent
Payment: $1945.79
Total Interest: $400,485.94

7.0 percent
Payment: $1995.91
Total Interest: $418,526.69

8.0 percent
Payment: $2201.29
Total Interest: $492,465.74

We all know that lower interest rates translate to lower payments, but looking at the rates laid out like this shows what a difference a full percentage point can make. A monthly payment on a 30-year mortgage for $300,000 increases by $197.26 from a loan with 6 percent interest to a loan with 7 percent interest.

If you want to play with Bankrate's mortgage calculator, you can find it and others here.