What is APY (Annual Percentage Yield)?
APY (Annual Percentage Yield) represents the real rate of return earned on an investment over a year, factoring in the effect of compounding interest. Unlike simple interest rates, APY assumes that earnings are reinvested periodically, meaning the actual yield can be higher than the nominal rate suggests.
In DeFi, APY is the universal metric for comparing returns across lending protocols, liquidity pools, staking contracts, and yield farms. When you see Aave advertising “5.2% APY on USDC” or a liquidity pool showing “42% APY,” that number represents the projected annual return assuming the current rate holds constant and rewards compound at the stated frequency.
However, DeFi APYs are notoriously volatile. A pool showing 200% APY today might drop to 8% next week as more capital flows in and dilutes the rewards.
APY vs APR: The Compounding Difference
| Metric | What It Measures | Compounding | Typical Usage |
|---|---|---|---|
| APR | Simple annual rate | No | Borrowing rates, staking base rewards |
| APY | Effective annual rate with compounding | Yes | Lending yields, liquidity mining |
The formula: APY = (1 + APR/n)^n − 1, where n = compounding periods per year.
Example: 10% APR compounded daily → APY = (1 + 0.10/365)^365 − 1 = 10.52%
At high frequencies (daily or continuous compounding, which is common in DeFi), the gap between APR and APY widens significantly:
| APR | Compounded Daily → APY | Compounded Continuously → APY |
|---|---|---|
| 5% | 5.13% | 5.13% |
| 20% | 22.13% | 22.14% |
| 100% | 171.46% | 171.83% |
| 500% | 14,477% | 14,714% |
This is why some protocols advertise APY instead of APR — it makes the numbers look more impressive.
Where DeFi APYs Come From
1. Lending Protocols (Aave, Compound)
When you supply assets to a lending pool, borrowers pay interest. The protocol takes a small cut (typically 10-15%) and passes the rest to suppliers. Rates are algorithmically set based on utilization:
- Low utilization (<50%): Low APY (2-4%), not enough borrowers
- Optimal utilization (80-90%): Peak APY (8-15%)
- High utilization (>95%): Extremely high APY (30%+), but signals liquidity risk
Typical stablecoin lending APYs: 4-8% in normal conditions.
2. Liquidity Mining (GMX, Camelot, Aerodrome)
Protocols incentivize liquidity providers with token rewards on top of trading fees. Total APY = fee APY + reward APY. Reward APYs can be 50-500% for new protocols trying to bootstrap liquidity, but these are temporary and drop as emissions decrease.
3. Staking (Lido, Rocket Pool)
Network-level staking yields are relatively stable:
- Ethereum: 3-5% APY
- Solana: 6-8% APY (with SOL inflation)
- Cosmos Hub: 12-15% APY
The APY Trap: What to Watch For
- Projection assumption: DeFi APYs are extrapolated from the last 24 hours or 7 days. They are not guaranteed.
- Reward token depreciation: If you earn 100% APY in a token that drops 90%, your real return is deeply negative.
- Impermanent loss: For liquidity pools, APY doesn’t account for IL, which can erase all gains.
- Compounding frequency manipulation: Some protocols compound every block (~12 seconds on Ethereum), inflating APY vs APR.
- “Free money” red flags: Stablecoin pools offering 50%+ APY often have hidden risks — rug pulls, oracle failures, or unsustainable emissions.
Frequently Asked Questions
Q: Is a high APY always better? A: No. A 300% APY on a new protocol’s token is far riskier than a 5% APY on Aave’s USDC pool. Always evaluate the risk behind the number.
Q: How often does DeFi compound? A: It depends on the protocol. Aave updates rates every block. Liquidity mining rewards may compound when you claim and reinvest, which could be daily or weekly depending on your strategy.
Q: Why did the APY drop after I deposited? A: More depositors means the same reward pool is split among more participants. This is especially common in liquidity mining programs where early depositors get outsized returns.