• 时间维度 · Time Horizon：
  工具先计算从当前年龄到目标退休年龄之间的年数（投资积累期），再计算退休后预计的生存年数（支出期）。
  The calculator first derives years from current age to target retirement age (accumulation phase), then uses years in retirement as the spending phase.
• 通胀与退休开支 · Inflation & Retirement Spending：
  输入的“退休后每月预期开支”是按今天的币值。工具会根据通胀率，把这个金额折算到“退休当年”应支出的名义金额；
  之后假设退休期间每月支出在名义上保持不变，用退休后的投资收益率折现，得到退休时点需准备的目标资产。
  The monthly spending you entered is in today’s purchasing power. The calculator inflates it to your retirement year using the inflation rate, assumes a constant nominal monthly spending during retirement, and discounts it at the post-retirement return to get the required nest egg at retirement.
• 资产累积 · Asset Accumulation：
  使用退休前的年化收益率，将当前储蓄按复利计算到退休时点，同时对每月固定储蓄做等额定投的未来价值计算， 两者相加即为“预计可积累资产”。
  Using the pre-retirement annual return, the calculator compounds your current savings to retirement and computes the future value of monthly contributions as a level savings plan; their sum is your projected assets at retirement.
• 资金缺口 · Funding Gap：
  若“预计可积累资产”小于“目标资产”，差额为资金缺口；反之则为盈余。你可以通过 调整退休年龄、每月储蓄金额或收益率假设来探索不同方案。
  If projected assets are below the required nest egg, the difference is the funding gap. Otherwise, it is a surplus. You can experiment by changing your retirement age, monthly savings or return assumptions.

说明：本工具采用固定收益率、固定通胀率与按月复利进行简化估算，未考虑个税、社保/养老金、 医疗大额支出、资产配置变化等复杂因素，仅作为个人理财与退休规划的学习和测算参考，不构成任何投资或规划建议。
Note: This tool uses simplified assumptions (fixed returns, fixed inflation, monthly compounding) and ignores taxes, public pension, large medical expenses, and asset allocation changes. It is for education and rough planning only and does not constitute investment or financial advice.