Q: How much money do I need to invest in a CD to get a good interest rate?

A: One of the best kept secrets in the banking industry is this: Certificate of Deposit rates vary. A lot. In some cases, larger deposits can buy a few more percentage points of interest, but unless you’ve got hundreds of thousands of dollars to spend, your total deposit value is probably negligible.

Some banks require a high minimum deposit to get a specific interest rate. Often this is a better rate than that for smaller deposits at the same institution, so it looks like a good deal. If you take the time to compare several institutions, however, you may find your good deal withering in the light of other offerings.

If you have a large amount of savings, you can make better rates with jumbo and brokered CDs. These high-minimum CDs ($100,000 or more) generally have higher interest rates than ordinary bank or credit union CDs. Be aware that many of these CDs are not covered by FDIC insurance, especially if your account value is greater than $250,000.

Of all factors, the term of the CD affects the interest rate the most. If you are willing to put your money aside for one, three or five years, you’ll get a greater interest rate than if you park it for one, three for five months — often a whole percentage point or more. Rates and terms vary greatly from bank to bank — call around and do an Internet search before you make your final decision. Be sure to read over the terms of the CD to make sure you understand all fees, renewal agreements and early withdrawal penalties.