TSP Funds Explained: G, F, C, S, I and the Lifecycle (L) Funds
The Thrift Savings Plan offers a handful of ultra-low-cost funds. Knowing what each one holds — and how the automatic Lifecycle (L) funds mix them — is most of what you need to invest well.
The five core funds
| Fund | What it holds | Risk |
|---|---|---|
| G Fund | Government securities — never loses value | Lowest (but lowest growth) |
| F Fund | U.S. bond market index | Low–moderate |
| C Fund | S&P 500 (large U.S. companies) | Higher / strong long-term growth |
| S Fund | Small & mid-cap U.S. stocks | Higher |
| I Fund | International developed-market stocks | Higher |
The Lifecycle (L) funds: set-and-forget
An L Fund automatically blends the five core funds based on a target retirement date (e.g., L 2055), holding more stocks when you're young and shifting toward G/F as you approach the date. For most members, picking the L Fund closest to when you'll need the money is a perfectly good one-decision strategy.
The classic young-member mistake
New members are auto-enrolled in an age-appropriate L Fund now — good. But for years the default was the G Fund, where decades of would-be stock growth were lost to a fund that barely beats inflation. If you're young and your money is sitting in G, you may be leaving a fortune on the table. Review your allocation.
Why TSP fees matter
TSP expense ratios are among the lowest of any retirement plan anywhere — a fraction of typical mutual-fund fees. Over a career, that fee gap alone can be worth tens of thousands of dollars. Combine the low fees with the 5% BRS match and a stock-heavy allocation when young, and the TSP is a wealth-building machine.
Set your TSP percentage in the calculator and watch your take-home update.
Calculate my pay →Frequently asked questions
What are the TSP funds?
Five core funds — G (government securities), F (bonds), C (S&P 500), S (small/mid-cap stocks), I (international stocks) — plus Lifecycle (L) funds that automatically blend them by target date.
Which TSP fund is best?
For long-term growth, stock funds (C, S, I) historically outperform; many members simply pick the Lifecycle (L) fund matching their retirement date. The G Fund is safe but barely beats inflation.
What's the TSP G Fund mistake?
Leaving money in the low-growth G Fund for decades when young — missing out on stock-market growth. New members are now auto-enrolled in an age-appropriate L Fund instead.