Compare the same balance over the same year

A higher savings rate can coexist with a worse outcome when fees consume the additional interest. The useful first comparison holds the balance and time period constant, then separates gross interest from account charges. This guide uses hypothetical dollar amounts and US disclosure terminology; it does not quote a live bank offer or recommend an account.

Regulation DD's APY calculation annualizes the relationship between principal and interest, accounting for the stated assumptions. Its framework is not a promise that a variable rate will stay unchanged throughout your comparison period. Use the disclosed APY as an input with a dated source, not as a guarantee. [1]

Write the assumptions before the result

For the basic model, use a starting balance that stays deposited for one year, a constant APY, no additional deposits or withdrawals, and fees paid from a separate source so they do not reduce the interest-bearing balance. Exclude taxes, inflation and any bonus. Those assumptions make the arithmetic transparent; they are deliberately narrower than most real accounts.

Record the fee schedule and every condition that changes a charge. The CFPB describes monthly maintenance fees and notes that account requirements can affect whether they are waived. Do not mark a fee as zero solely because a waiver exists: record whether your intended use satisfies it. [2]

An invented comparison with a $6 monthly fee

Imagine Account A has a constant 4.0% APY and a $6 monthly fee. Account B has a constant 3.5% APY and no fee. At a $10,000 balance, modeled gross annual interest is $400 for A and $350 for B. Twelve fees cost $72, so A yields $328 after fees in this simplified model; B yields $350. A's higher APY leaves it $22 behind.

The extra yield is 0.5 percentage points, or 0.005 as a decimal. Divide the $72 annual fee difference by 0.005: the modeled break-even balance is $14,400. At $20,000, A produces $800 less $72, or $728; B produces $700. This is original arithmetic from invented inputs, not a quoted bank return.

Know when the shortcut stops working

If the APYs are equal and one account costs more, no positive balance offsets that extra fee within this model. If the fee-bearing account has the lower APY, increasing the balance does not repair the disadvantage. If rates or fees change, calculate separate periods or use the bank's actual interest method rather than extending the one-year shortcut.

When fees are deducted from the account, the future interest-bearing balance also changes. Monthly deposits, withdrawals, tiered rates and qualifying-balance rules likewise require a more detailed cash-flow model. Our existing savings calculator excludes fees, so its growth projection should not be mistaken for this net-fee comparison. Keep both limitations next to any saved result.

Use the worksheet as an evidence record

Compare account access and conditions alongside the result: transfer timing, supported services, minimum balances, the exact institution and product, and the applicable deposit-protection scheme. A familiar brand name or an app interface is not enough information to establish protection for a particular balance. Verify those matters directly before making a deposit decision.

Save one row for each scenario and note which inputs are official terms, personal estimates or still unknown. Recalculate after a rate change or a missed waiver condition. If a small apparent advantage depends on uncertain inputs, record the uncertainty instead of presenting the spreadsheet as a ranked recommendation. The goal is a defensible comparison of your assumptions, not the highest-looking headline.

Follow the sources

Provider terms can change. Recheck the linked source before applying or subscribing.

APY and fee comparison worksheet