TSP Fund Allocation Calculator

For FERS federal employees: find your recommended split across the G, F, C, S, and I funds — with a built-in adjustment for your pension as fixed income. Enter your situation and see the recommended allocation plus the equivalent Lifecycle fund.

Why this calculator is different from a generic target-date fund tool

Most allocation calculators — and the TSP's own L Fund defaults — are designed for investors whose only retirement income is their investment portfolio. They assume that if you retire at 62, you need the portfolio to cover 100% of your expenses, so they de-risk aggressively in the years before retirement.

FERS employees are in a different situation.

This calculator adds a pension-coverage adjustment on top of a standard time-horizon-based allocation. The larger your pension coverage, the more equity the model allows — because your pension is already doing the "bond" work in your retirement income.

How to read the results

Equity vs. fixed income split

The most important output is the total equity percentage (C + S + I funds combined). This drives most of your long-term return and your volatility. The fixed income portion (G + F funds) provides stability and, in the case of the G Fund, principal protection with a guaranteed yield.

G Fund vs. F Fund

Within the fixed income allocation, the model shifts from F-heavy (early career) to G-heavy (near and in retirement):

• Early career (10+ years out): More F Fund — the Bloomberg US Aggregate index offers some return opportunity and modest diversification. You have time to recover from duration-risk losses.
• Near retirement (5–10 years out): Balanced G/F split — transition to more stability.
• At or near retirement (0–5 years out): Mostly G Fund — principal-guaranteed, no duration risk, currently earning ~4.3% annualized. The G Fund is one of the strongest arguments for keeping money in TSP rather than rolling to an IRA — it doesn't exist outside TSP.

C / S / I equity split

Within the equity portion, the model uses approximately the same equity mix that the TSP's own L 2055–2075 funds use:¹

• C Fund (~46% of equity): S&P 500 exposure at 0.035% expense ratio.
• S Fund (~18% of equity): U.S. mid/small-cap completion — combined with C, approximates a total U.S. market index.
• I Fund (~36% of equity): International developed markets ex-China/HK. After the 2024 benchmark overhaul (MSCI ACWI IMI ex US ex China ex HK), the I Fund covers 40+ countries and 5,100+ stocks.

This is not the only defensible equity split — some advisors prefer overweighting C or underweighting I — but it mirrors the FRTIB's own long-run default and keeps you well-diversified across U.S. and international markets.

Comparable Lifecycle fund

The results show the L Fund whose equity percentage most closely matches your recommended allocation. This tells you whether you should be more aggressive or more conservative than the L Fund auto-enrollment default. Many FERS employees discover they could reasonably hold an L Fund one or two steps more aggressive than what TSP auto-enrolled them in.

One thing the L Fund does that a custom allocation doesn't

If you follow a custom G/F/C/S/I split, your allocation will drift as markets move — the C Fund might grow to 55% of your portfolio in a strong equity year when you intended 46%. L Funds rebalance automatically every quarter back to their target weights. With a custom allocation, you need to rebalance manually (you can do this in TSP's online portal with no transaction costs). The TSP allows two inter-fund transfers per month at no cost.

If manual rebalancing isn't something you'll realistically do, using the comparable L Fund is often the more practical choice — the cost is small and the discipline is automatic.

Important limitations

• This calculator estimates a starting point, not a personalized recommendation. Your specific income needs, sequence-of-returns risk, tax situation (Roth vs. Traditional TSP), health, and survivor benefit elections all affect the right answer for your situation.
• The pension coverage percentage is self-reported and approximated. If your FERS annuity plus Social Security genuinely covers 90%+ of expenses, a higher equity allocation may be well-justified — but someone needs to verify the math with your actual numbers.
• This tool does not model Roth vs. Traditional TSP contributions or tax-bracket optimization. Those are separate decisions covered in the Roth vs. Traditional TSP guide.