Practical guide
Understanding savings account comparison — target starting balance
Everyday editorial team · GEOINNOVATION CO., LTD · Published · Updated
What this calculation is for
A savings-account comparison puts balances, deposits, yields and recurring fees on the same timeline. A small APY difference can be outweighed by a monthly account fee, especially at modest balances.
How the method works
Both accounts start with the same principal and monthly contribution schedule. Each uses its own assumed APY, while the specifically labeled account fee reduces the applicable contribution stream. The displayed model uses: Calculate monthly growth and contributions separately for each account, then subtract fees.
A worked example
For an illustrative savings account comparison scenario, use Starting balance: 10000 $; Monthly deposit: 300 $; Account A APY: 4.5 %; Account B APY: 3.75 %; Monthly fee for account A: 0 $; Comparison term: 3 years. The modeled higher projected account balance is $22,936.02. These are example assumptions, not current prices, official benefit amounts or personalized advice.
Assumptions and real-world differences
Rate tiers, promotional expiration, minimum balances, fee waivers and taxes are not looked up. Do not enter a monthly fee again if you already reduced the deposit by that fee. Rates and fees are held constant. Tax effects and promotional terms are excluded.
Solving for starting balance
This reverse calculation searches for a starting balance that makes the model’s headline measure approach your target. Set a lower and upper search bound, leave the other assumptions consistent, and inspect the achieved result and target difference. The returned number is an input, not the original model’s output. A bounded solution can be approximate when the allowed input step rounds values.
Reproduce this tool’s example
These fixed example inputs are independent of edits you make above. Enter them in this tool to reproduce the result, then replace them with your own assumptions.
- Target: higher projected account balance
- 22,936.02 $
- Minimum starting balance
- 5,000 $
- Maximum starting balance
- 15,000 $
- Monthly deposit
- 300 $
- Account A APY
- 4.5 %
- Account B APY
- 3.75 %
- Monthly fee for account A
- 0 $
- Comparison term
- 3 years
Required starting balance: $10,000
Closest modeled result: $22,936.02.
- Target headline value: 22,936.02
- Calculated headline value: $22,936.02
- Absolute target difference: 0
Frequently asked questions
- Is the larger projected balance a bank recommendation?
- No. Access, deposit protection, account requirements and future terms also matter.
- Which inputs should I check before using this savings account comparison estimate?
- Check starting balance, monthly deposit, account a apy, account b apy, monthly fee for account a, comparison term. Match each field’s unit and time period, then compare the detailed rows rather than treating the headline alone as the complete answer.
- Why might there be no exact required starting balance?
- The target may be outside the search range. Rounded outputs, whole-item counts, tax thresholds and flat responses can also prevent an exact solution. Bisection requires a monotonic response within the chosen range; do not interpret a failed search as a real-world impossibility.