The first step is to assess the condition of each individual baseball card. The condition is one of the biggest factors that will determine the value. For modern cards printed after the 1980s, condition is assessed using the PSA grading scale of 1 to 10, with 10 being flawless gem mint condition. Carefully examine each card for any marks, scratches, corners that are bumped or dulling of the color. Make notes of any flaws.

Now you’ll want to do some research to understand how different condition grades impact value. The lower the grade the less valuable a card will be. A common rule of thumb is each downgrade in condition can cut the value in half. For example, a card graded a 9 would be worth around half as much as the same card earning a gem mint 10 grade. Condition guides are available online from major card grading companies like PSA, BGS, SGC that provide estimated value ranges for cards across different condition grades to use as a starting reference point.

Once you’ve assessed condition, the next step is to identify key details about each card like the player, year, brand (Topps, Fleer, etc.), and any notable serial numbers, variations, or parallels. Taking photos of the front and back of each card is very helpful for research purposes later. Recording all relevant identification details for each card you want to value is important.

With condition and identification details noted, you can then begin researching recently sold prices of comparable cards online. The best resources for this are online auction sites like eBay, as well as price guide subscription sites. On eBay, use the “sold listings” filter to only view cards that have already been successfully sold to see what buyers were actually willing to pay. Comparing your cards to recently sold identical or near identical listings will give you a very accurate real market value indicator.

If your cards are valuable rookie cards, autographed cards, or rare serial numbered parallels it’s important to also check price guide subscription sites. Websites like PSA SMR Price Guide, Beckett, and Baseball Card Price Guide provide expert-generated market values and trends over time for higher end collectibles. Looking up recently sold auction prices and price guide estimated values will together give you a solid valuation range for each card.

Now you’ll also want to factor in certain card show or online auction sale fees when valuing your cards. Major card shows and popular auction houses like Goldin Auctions typically take a 10-15% sellers commission. So to determine the net amount you could reasonably expect to pocket, estimated values would need to be adjusted down by the applicable fee amount, assuming a sale through one of those major platforms. Private sales conducted yourself have no fees obviously.

Once you’ve gone through this process of assessing condition, identifying details, and researching recent sold prices for each individual card, you’ll have a clear idea of what collectors are currently paying for your baseball cards on the open market. Keep good records of your findings, as values can fluctuate over time. Periodically checking in on your valuable cards is a good way to monitor changes in their estimated worth. With effort and research, you’ll be equipped with knowledgeable baseball card values.