What Is Compound Interest?
Compound interest means earning returns on both your original investment and the returns you've already earned. In crypto, this happens when you reinvest staking rewards, lending interest, or yield farming profits instead of withdrawing them.
Simple vs Compound Interest
- Simple interest: You earn 10% on 100 USDC = 10 USDC/year, always on the original 100
- Compound interest: Year 1: 110 USDC, Year 2: 121 USDC, Year 3: 133 USDC — earnings grow each period
Where It Happens in Crypto
- Staking: Validators re-stake rewards automatically (e.g., SOL, ATOM, ETH)
- Lending: Platforms like Aave compound interest per block
- Yield farming: Auto-compounding vaults (Yearn, Beefy) harvest and reinvest
- Liquid staking: stSOL, mSOL grow in value as staking rewards accrue
Key Factors That Affect Compounding
- Frequency: Daily compounding beats monthly; per-block (Solana/Ethereum) is fastest
- APY vs APR: APY includes compounding; APR doesn't. Compare APY to APY
- Fees: Platform fees reduce effective yield — check the net APY
- Token price: If the reward token drops, compounding in token terms ≠ USD terms
A Quick Example
Stake 1,000 SOL at 7% APY, compounded daily.
After 1 year: ~1,072.5 SOL (vs 1,070 with simple interest).
After 5 years: ~1,419 SOL (vs 1,350 simple).
Risks to Watch
- Smart contract risk — the protocol could be hacked
- Impermanent loss in liquidity pools
- Reward token inflation diluting value
- Lock-up periods preventing quick exit
Start Small, Learn First
Try a small amount on a reputable protocol. Track your actual APY vs advertised. Compound interest is powerful — but only if the underlying yield is real and sustainable.