Which Card Should I Use for This Purchase? A Free Tool That Shows the Math

A 6% grocery card earns 1% at Walmart.

That is not a bug in your card. Walmart codes as a superstore at the card networks, not a supermarket, so grocery bonus categories on most cards skip it entirely. Costco has the same problem, plus a second one: the warehouse only takes Visa. Tesla Superchargers often code as automotive services, so your gas bonus may never trigger.

This is why "just use the dining card for dining" advice falls apart at the register. The right card depends on the amount, the category, how the merchant actually codes, whether you have hit a spending cap, and what your points are worth to you.

We built a tool that does that math in about ten seconds. Try it right here:

What it does

You add the cards you carry, by name, from a catalog of 135 cards. Then you enter a purchase: the amount, the category, and optionally the merchant. The tool ranks your wallet and shows the winner with the work:

3x Dining × 1.5¢/pt × $64 = $2.88

Runner-up cards appear below it with the gap, so you can decide whether $1.60 of difference is worth fishing a different card out of your pocket.

Every answer comes with its assumptions listed and a confidence level. If the recommendation depends on a rotating quarterly category you had to activate, the tool says so. If the merchant you typed has a coding quirk, you get the warning before you swipe, including the Visa-only flag when your best card will not be accepted at Costco.

Point values are yours to edit. If you only redeem for cash, leave them at 1¢. If you transfer to airline partners, set 1.5¢ or 2¢ and watch the winner change. That choice can flip the answer, which is exactly why we refuse to hide it.

What it doesn't do

No bank login. No card numbers. No transaction history. You pick cards by name and your wallet stays in your browser. If you have a CardSavvy account, the wallet you already saved in the optimizer loads automatically and stays in sync.

One purchase vs. your whole year

Best Card answers the question in front of you at checkout. The Wallet Optimizer answers the bigger one: across a year of spending, which cards should you carry at all, after annual fees and credits? They share the same wallet, so the two tools compound. Run the optimizer once a quarter; ask Best Card whenever you are standing at a register.

If you write about credit cards, you can also embed this tool on your own site for free.

Quick decision guide

• At a supermarket: your grocery card wins. At Walmart or Target, it probably doesn't.
• At Costco: check the Visa-only warning before you reach the register.
• Booking travel: airline-direct and OTA bookings code differently. The tool knows which.
• Not sure: type the merchant and let the math decide.

Try Best Card →