FIELD GUIDE · Extrafund
Compare savings scenarios with the same inputs
Use matching contribution amounts and timelines to see what changes between savings or retirement planning scenarios.
Editorial review:
Choose one question
Pick a decision the calculator can help frame, such as whether a different monthly contribution changes a long-term savings projection. Keep the goal and timeline explicit. A calculator can compare its own assumptions; it cannot confirm your eligibility for an account, employer benefits, future income or retirement readiness.
Write down which inputs you know and which are guesses. If you do not know fees, a match formula or a contribution limit for your plan, do not quietly substitute a default and treat it as a fact.
Keep the baseline constant
Set the same starting balance, contribution timing and time horizon in both scenarios. Change one input at a time so you can see which assumption moved the result. For example, compare a $300 monthly contribution with $400 over the same years and under the same return and fee assumptions. The difference isolates the contribution change inside that model.
Then run a second comparison that changes a different assumption, such as lower growth or higher fees, while restoring the original contribution. This is a sensitivity check, not a forecast of what markets will do.
Read the estimate with its limits
Review the app's assumptions for inflation, fees and any modeled employer match. Extrafund models a single employer-match tier; it does not verify a person's plan terms or eligibility. A projection can omit taxes, debts, contribution caps, changing income or other facts that matter to a real decision.
If the app displays a monthly plan, treat it as a personal scenario to review rather than an instruction to move money. The tools do not execute trades, transfers or account changes. Verify current plan rules and account terms with the institution or official source before acting.
Save and revisit the comparison
Keep a short note beside the saved plan stating the question, changed input and date you checked it. Review the scenario when your contribution, goal, fees or time horizon changes. Compare the same inputs again rather than treating a prior projection as a promised balance.
The web and iPhone app support local plans, goals and scenarios; optional linked-account analysis is a separate feature with its own permissions and data coverage. A saved estimate is not personal financial, tax or investment advice.