Which Credit Card to Use for Every Purchase

With three cards, picking the right one at the till is easy. With eight, it isn't: caps run out, rotating categories change every quarter, and the same “3%” is worth different amounts depending on what else is in your wallet. This is how to work it out, and how Churn does it for you.

Step 1: compare value, not the number on the card

A rate is only comparable once it is in cents per dollar. Cash back is already there: 2% is 2 cents. Points need a value per point. Churn uses its own table, for example 1.7 cents for Chase Ultimate Rewards and 1.8 cents for Amex Membership Rewards. At those values, 3x Ultimate Rewards is worth 5.1 cents per dollar and 4x Membership Rewards is worth 7.2 cents. In Canada, where Churn values Amex Membership Rewards at 1.3 cents, the Cobalt's 5x at restaurants in Canada is worth 6.5 cents.

You can disagree with any valuation; what matters is using the same one for every card. Churn's valuations page lists the figure for each program.

Step 2: let the wallet change the value

Some cards earn bank points that are only worth full value next to another card. The Chase Freedom Unlimited earns 1.5% on everyday purchases. On its own, that is 1.5 cents. Next to a Sapphire Preferred or Reserve, or an Ink Business Preferred, the same points can move to a card that transfers them to airlines and hotels, so Churn counts them as 1.5x Ultimate Rewards: about 2.55 cents.

That is why the pair is popular. For dining the two tie: the Sapphire's 3x and the Freedom's 3% are both 3 points a dollar once they sit together. For everything without a bonus, the Freedom wins, at 1.5 points against the Sapphire's 1.

Step 3: count the caps

Many top rates stop at a spending limit. The Amex Gold earns 4x at US supermarkets on up to $25,000 a year, then 1x. The Blue Cash Preferred earns 6% at US supermarkets on up to $6,000 a year, then 1%. If you spend $8,000 a year at supermarkets, the Blue Cash Preferred's top rate covers three quarters of it, and the last $2,000 belongs on another card.

Step 4: check this quarter's categories

Rotating cards like the Chase Freedom Flex pay 5% on categories that change every quarter, on up to $1,500 of combined spending, and only after you activate them. Outside those categories the card earns its base rate. A rotating card is the best card for a category three months at a time and an ordinary card the rest of the year.

Step 5: fill the gaps, then stop

Once each of your big categories has a card earning well on it, the next card adds less than you think. Once your cards are in, the discover page in the Churn app shows which categories your wallet covers weakly and which catalog cards would cover them, so a new card is a decision about a gap rather than a bonus alone.

Pro adds a Missed Rewards report that compares what you earned with what the best card in your wallet would have earned on the same spending; see Churn Pro pricing.

A simple rule for the till

1. Is this a category one of your cards pays a bonus on? Use it.
2. Has that card reached its cap this year or quarter? Use the next one.
3. Is it a rotating category this quarter, and is it activated?
4. Nothing special? Use your best everyday card, which may be the one that earns transferable points rather than the one with the highest number.

For category-by-category lists, see the best cards for dining, groceries and gas and EV charging, and points vs. cash back for the valuation question.