DB vs DC Plan Calculator
Compare a defined benefit pension vs a defined contribution plan.
What this calculator does
This calculator puts a defined benefit pension and a defined contribution balance on the same scale. It projects the DC account forward at your expected return, and converts the monthly pension into the capital that would be needed to generate the same income at a chosen withdrawal rate, so the two can be compared directly.
That conversion is the only honest way to weigh a guarantee against a balance. A pension statement shows a monthly figure and a 401(k) statement shows a lump sum, and most people instinctively over-weight the number that looks larger, which is almost always the one with more digits rather than more value.
When to use it
The clearest use is choosing between job offers where one carries a traditional pension and the other a stronger 401(k) match. Converting both to a common unit turns a benefits-brochure comparison into an arithmetic one, and the pension frequently wins by more than candidates expect if they intend to stay long.
It is also the tool for a lump sum buyout decision, and for the annuity versus lump sum election most pensions offer at retirement. In both cases you are being asked to trade a guaranteed income for capital, and the first thing to establish is what that income is actually worth.
Understanding the inputs
Expected DB pension per month should come from your plan's benefit statement, and you should check whether it is a single life or joint and survivor figure, and whether it includes any cost of living adjustment. An unindexed pension deserves a lower valuation than the headline arithmetic suggests.
Monthly DC contribution should include your deferral plus every employer dollar. Expected return should be conservative, because the whole point of the comparison is that only one side carries market risk. Running the DC projection at 8 percent while treating the pension as merely guaranteed misrepresents the trade-off you are evaluating.
How is this calculated?
DC balance grows via compound interest. DB value is calculated as: Annual Pension / Withdrawal Rate (Equivalent Capital).
A worked example
Contributing $800 a month to a 401(k) for 25 years at 6.5 percent builds roughly $599,000. A pension paying $2,500 a month is $30,000 a year, which at a 4 percent withdrawal rate is equivalent to $750,000 of capital. The pension is ahead, and it carries no market risk at all.
The comparison is sensitive to the rate used. Value the same pension at 3.5 percent, appropriate if it were inflation-adjusted, and it rises to roughly $857,000. But if it is a level private sector pension with no adjustment, its real value falls every year, and after 15 years at 3 percent inflation it buys about $19,300 of today's goods.
Limitations and assumptions
These are projections under fixed assumptions, not predictions. The DC side applies one flat return with no volatility, so sequence-of-returns risk is invisible even though it is the largest single threat to a balance you must draw down yourself. The actual balance could differ substantially even if the average return proves right.
The DB side is capitalized with a simple withdrawal rate, ignoring your health and actual longevity, survivor elections, vesting schedules, plan funding status, whether the benefit is indexed, and income tax on either stream. It also excludes Social Security, which sits alongside both. Use plan documents for anything binding.
Common Questions
- Which plan is actually better?
- It depends on what you value. A defined benefit plan guarantees income for life and puts all the investment and longevity risk on the employer. A defined contribution plan gives you a balance you own, can move between jobs, and can leave to heirs. Neither dominates; they fail in different directions.
- How do I compare income against a balance?
- Divide the annual pension by a withdrawal rate to get an equivalent capital sum. At 4 percent, a $30,000 pension equates to $750,000 of savings. Use 3.5 percent if the pension is indexed to inflation, since replicating an inflation-linked income safely requires a lower withdrawal rate and therefore more capital.
- Why did most private pensions disappear?
- Because the risk and cost sat with the employer. Longer lifespans, falling interest rates that inflated the value of promised benefits, and tighter funding rules made open plans very expensive. Only about 15 percent of private sector workers now have access to one, against roughly half in the early 1980s.
- How much is portability worth?
- More than it once was. Defined benefit formulas reward long service heavily, because the benefit is calculated on final average salary but frozen at your salary when you leave. Someone changing employers every five years accrues far less from a series of pensions than a 401(k) balance that moves with them.
- What if the pension plan fails?
- The Pension Benefit Guaranty Corporation insures most private single-employer plans up to a statutory maximum exceeding $7,000 a month at 65. Most retirees are fully covered. Multiemployer plans have a much lower guarantee, and some remain seriously underfunded, so the plan's funded status is worth checking.
- Should I take a lump sum buyout?
- Compare the offer against the capital equivalent of the pension. A $500,000 offer for a $35,000 annual pension values it at a 7 percent withdrawal rate, which is difficult to sustain safely. Buyouts are typically calculated using segment rates that make them less generous when interest rates are high.
- Does a DB pension have a cost of living adjustment?
- Private sector plans usually do not, which is their quiet weakness. A level $30,000 pension buys roughly $19,300 of today's goods after 15 years at 3 percent inflation. Public sector and federal FERS annuities often include some adjustment, though frequently capped below full inflation.
- Which is better to leave to family?
- The DC balance. A 401(k) or IRA passes to beneficiaries, who generally have ten years to draw it. A single life pension stops when you die, and a joint and survivor election, which continues income to a spouse, reduces your own payment by typically 10 to 25 percent.
- Can I end up with both?
- Yes, and it is the strongest position. Many employers with a legacy pension also offer a 401(k), and public sector employees frequently have a pension alongside a 457(b) or 403(b). The pension covers fixed costs while the invested balance provides flexibility, which is exactly how a retirement income plan should be layered.
- What about cash balance plans?
- They are technically defined benefit but presented as a notional account balance credited with a percentage of pay plus interest. They are portable like a DC plan and guaranteed like a DB plan, and they have become common among professional partnerships wanting large deductible contributions for older owners.