Pension Calculator
A pension calculator estimates your defined benefit pension payments based on years of service, salary, and your plan's benefit formula. Pensions provide guaranteed lifetime income in retirement.
Common Pension Formulas
Most pensions use a multiplier formula:
Annual Pension = Years of Service × Multiplier × Final Average Salary
| Multiplier | 20 Years Service | 30 Years Service | 35 Years Service |
|---|---|---|---|
| 1.5% | 30% of salary | 45% of salary | 52.5% of salary |
| 2.0% | 40% of salary | 60% of salary | 70% of salary |
| 2.5% | 50% of salary | 75% of salary | 87.5% of salary |
Pension Benefit Examples
Final Average Salary: $80,000
| Years | 1.5% Multiplier | 2.0% Multiplier | 2.5% Multiplier |
|---|---|---|---|
| 20 | $24,000/year | $32,000/year | $40,000/year |
| 25 | $30,000/year | $40,000/year | $50,000/year |
| 30 | $36,000/year | $48,000/year | $60,000/year |
| 35 | $42,000/year | $56,000/year | $70,000/year |
Pension Calculator Implementation
``javascript
function calculatePension(yearsOfService, finalAvgSalary, multiplier, earlyRetirement = false) {
let basePension = yearsOfService * (multiplier / 100) * finalAvgSalary;
// Early retirement reduction (typically 5-6% per year before normal retirement)
const reduction = earlyRetirement ? 0.05 * 5 : 0; // Assume 5 years early
const adjustedPension = basePension * (1 - reduction);
return {
annualPension: adjustedPension.toFixed(2),
monthlyPension: (adjustedPension / 12).toFixed(2),
replacementRate: ((adjustedPension / finalAvgSalary) * 100).toFixed(1) + '%',
earlyReduction: (reduction * 100).toFixed(0) + '%'
};
}
console.log(calculatePension(30, 80000, 2.0));
// { annualPension: '48000', monthlyPension: '4000', replacementRate: '60%' }
`
Lump Sum vs Annuity
Some pensions offer lump sum buyouts. Compare the lump sum to the present value of lifetime payments using your expected lifespan and discount rate.
The Projection Behind This Page
Starting from $50,000, adding $200 a month at 2%:
| Year | Deposited | Balance | Growth | Growth on deposits |
|---|---|---|---|---|
| 1 | $52,400 | $53,431 | $1,031 | 2% |
| 5 | $62,000 | $67,863 | $5,863 | 9% |
| 10 | $74,000 | $87,604 | $13,604 | 18% |
| 13 | $81,200 | $100,430 | $19,230 | 24% |
| 25 | $110,000 | $160,166 | $50,166 | 46% |
After 25 years, 31% of the balance is growth rather than money you
put in. That crossover — the point where returns exceed contributions — is the whole reason
compounding is worth waiting for, and it arrives later than most people expect.The Formula
`
A = P(1 + r/n)^(nt) + PMT × [((1 + r/n)^(nt) − 1) ÷ (r/n)]
└── initial principal ──┘ └────── regular contributions ──────┘
`
The second term usually dominates. On these numbers the $200 monthly contribution
accounts for the larger share of the final balance, which is the practical lesson: how much
you add matters more than the rate, right up until the balance gets large.
How Long Until It Doubles
The Rule of 72 divides 72 by the rate to estimate doubling time. At 2%:
`
72 ÷ 2 = 36.0 years
`
The exact answer is 35.0 years — the rule is accurate to within a few months
for rates between 6% and 10%, and drifts at the extremes. It works because ln(2) ≈ 0.693 and
72 has convenient divisors.
| Rate | Rule of 72 | Exact |
|---|---|---|
| 2% | 36.0 yr | 35.0 yr |
| 5% | 14.4 yr | 14.2 yr |
| 7% | 10.3 yr | 10.2 yr |
| 10% | 7.2 yr | 7.3 yr |
| 15% | 4.8 yr | 5.0 yr |
Compounding Frequency at This Rate
A nominal 2% turns into a different effective yield depending on how often it
compounds:
| Compounded | Effective annual yield |
|---|---|
| Annually | 2.000% |
| Quarterly | 2.015% |
| Monthly | 2.018% |
| Daily | 2.020% |
| Continuously | 2.020% |
The gap between annual and monthly is worth having. The gap between monthly and daily is
0.002 percentage points — rounding. Compare accounts on
APY, which already folds the frequency in, rather than on the nominal rate.Inflation Is the Number That Matters
A 2% nominal return against 3% inflation is a -1.0% real return.
Real return is what buys anything:
`
real ≈ nominal − inflation
``
Over 36 years, 3% inflation cuts purchasing power by about 65%. A projection quoted in nominal dollars therefore overstates what the money will actually be worth, which is why retirement targets are usually stated in today's dollars.