Inflation erodes the purchasing power of money over time. Its effects on your life depend on how well your income and investments do keeping up. Take a look at these sites to see how you're doing.

Digging the data. is a personal-finance site edited by Tim McMahon. It posts a current inflation rate, based on the government's Consumer Price Index for All Urban Consumers, of 2.65 percent. The site is rich in articles, charts and links on housing, employment, other economic matters that go into the cost of living, and calculators for doing some figuring on your own.

Grim calculation. Pick a dollar number and a year, and this calculator at the U.S. Bureau of Labor Statistics will tell you what buying power those dollars had compared with the dollar's current value. For example, $100 in 1962 had the same buying power that $760 has today, according to the calculator. That's a good argument against mattress savings accounts, if nothing else.

Not so simple. The Bureau of Labor Statistics has extensive material on inflation, and it can get bewildering. Beyond the Consumer Price Index, in its various forms, there are inflation measures for producer prices, employment costs, contract escalation, and international consumer prices. These different measures show how inflation hits people differently. You can dive into the data here:

Shadow stats. You trust the government to get it right? Not so fast, say the editors at Shadow Government Statistics, where changes in the way the inflation rate is calculated over the years are examined. Using a method employed by the United States before 1990, according to this site, would put the current rate at a worrisome level of about 6 percent.

Global inflation. World inflation is the subject of this page maintained by the Federal Reserve Bank of Cleveland, where you can choose one or more countries, or all of them, to generate a graph of inflation over time. Click "Research" near the top of the page to investigate more of what the site offers on inflation expectations.

Contact staff writer Reid Kanaley at 215-854-5114, or @ReidKan on Twitter.