College Savings Monthly Contribution Calculator accuracy and testing

Formula source

• Projected cost sums each school year as current annual cost x (1 + inflation)^(years until enrollment + school year index). Remaining goal = projected cost - future value of current savings. Monthly contribution solves the PMT needed at the entered monthly return.

Test cases

Known limitations

• These calculators do not fetch local prices, predict provider changes, model taxes or eligibility rules, or replace professional advice. The result is only as reliable as the assumptions entered.

Assumptions

• All costs, rates, schedules, subsidies, returns, and inflation assumptions are user-entered.
• Calculations are deterministic and run locally in the browser; Calwarden does not upload or store family budget inputs.
• Savings projections are estimates only and are not financial, tax, investment, or college-planning advice.

Unit handling

• Current Annual Cost accepts values in $.
• Years Until Enrollment accepts values in years.
• Program Length accepts values in years.
• Current Savings accepts values in $.
• Annual Return Assumption accepts values in %.
• Annual Cost Inflation accepts values in %.
• Estimated Monthly Contribution is displayed as currency.
• Projected Total Cost is displayed as currency.
• Future Value of Current Savings is displayed as currency.
• Remaining Goal is displayed as currency.

Rounding rules

• Number displays use up to 2 decimal places in the calculator UI.
• Currency outputs are displayed with standard US dollar formatting.
• Input precision follows configured step values where provided.

Version history

Change log