Separate the target from the projection
A savings projection estimates a future balance under entered assumptions. A retirement target starts with the spending and support you may need. Neither is complete on its own: a large balance does not establish readiness unless it is compared with expenses, other income and the number of years the money must support.
List current savings from statements and keep them separate from planned contributions. Avoid counting the same workplace account in two starting balances. Use the retirement and 401(k) tools to explore different saving paths rather than adding their outputs together when they describe overlapping accounts.
Use several return and timeline assumptions
A constant return makes the arithmetic easy to compare, but actual investments do not follow a smooth path. Run a lower-return scenario with the same contribution and retirement date. Then test a different contribution or date separately to see which change explains the improvement.
Employer match can add to a workplace account, but plan terms may limit it or require time before it is fully yours. Confirm the rules rather than assuming an entered match applies to every dollar contributed. Fees and taxes can also affect what is eventually available to spend.
Compare tax treatment and purchasing power
A Roth-versus-traditional comparison depends on tax assumptions now and at withdrawal, as well as the way contributions are compared. It is not a universal recommendation for one account type. Read the tool's assumptions and consider whether you are comparing equal contributions or equal current out-of-pocket costs.
Inflation separates a future dollar balance from its purchasing power. Use the same dollar basis on both sides of a comparison: a future balance should not be directly judged against today's spending goal without an adjustment. An assumed inflation rate is a scenario, not a forecast.
Plan beyond the average result
Withdrawal estimates such as a simple percentage of savings are planning heuristics, not guaranteed safe income. Outcomes depend on spending changes, investment mix, the sequence of market returns, taxes and how long retirement lasts. Poor early returns can matter even when a long-run average looks reasonable.
Net worth gives a broader asset-minus-debt picture, but not every asset is easily spendable. Home equity and retirement accounts can have access constraints or costs. Keep emergency liquidity, other income sources and important personal risks in the discussion, and seek qualified advice before committing to an irreversible retirement decision.