Reference formulas and worked examples below keep their stated units. Monetary examples use USD; dimensional examples use US customary units unless labeled otherwise. Metric calculator inputs are converted to these reference units before calculation. Choosing another currency does not convert example amounts or exchange money.
How to use this retirement calculator
Set current, retirement and plan-end ages. Enter saving and retirement spending, then inspect the annual timeline and required monthly contribution.
How the calculation works
During accumulation, apply the effective monthly return to the opening portfolio, then add the scheduled monthly saving. Saving grows on each annual anniversary by the entered contribution-growth rate.
After retirement, apply the retirement return, then fund spending less entered retirement income. Both spending and income are specified in today’s money and rise annually from the start of the plan. Withdrawals cannot exceed available funds; unfunded spending remains a shortfall.
Work backward from the desired final reserve through retirement cash flows to determine the reserve needed at retirement. Then solve for the minimum starting monthly contribution, in cents, that reaches that reserve under the accumulation assumptions.
Results distinguish retirement-date assets, required assets, the first unfunded spending month, nominal ending funds and their purchasing power. Income above spending is not reinvested.
Worked example
With age 64 now, retirement at 65, plan end at 66, no starting assets, no returns or inflation, $1,000 monthly retirement spending and no other income, the retirement year needs $12,000. Saving $1,000 each month for the preceding year exactly funds it.
Limits and assumptions
A deterministic scenario, not a success probability or individualized financial recommendation. One income stream begins at retirement; no delayed benefit start, taxes, account limits, market sequences, changing asset allocation, irregular one-off costs or healthcare model. If no saving years remain or required saving exceeds model limits, that limitation is stated.
Frequently asked questions
Does this include saving and retirement withdrawals?
Yes. The annual timeline separates the accumulation and retirement phases while keeping inflation and cash-flow units explicit.
Are spending and retirement income future amounts?
Enter them in today’s money. The model inflates them from now and uses the resulting nominal amounts after retirement.
What does required monthly saving mean?
It is the smallest starting contribution, rounded to a cent, that satisfies this fixed scenario through the plan-end age and reserve. It follows the selected annual contribution increases.
Can I model already being retired?
Yes. Set retirement age equal to current age. With no accumulation period, an underfunded plan cannot be repaired by a pre-retirement monthly-saving answer.
Does passing the scenario guarantee the money lasts?
No. Returns, inflation, income and spending are assumptions. The tool does not simulate market uncertainty or probability.