Your DEX tool is probably overstating Uniswap v3 TVL by 25x

I shipped a bug into a paid API and it took me a while to see it, because nothing errored. Every response was a clean HTTP 200 with a confident number in it. The number was wrong by 25x . Here is the finding, the arithmetic, and how to check your own code in about thirty seconds. The measurement Uniswap v3, WETH/USDC on Base. Left column is what my API reported as TVL. Right column is what the pool contract actually holds — a plain balanceOf on each token, at the pool address. pool reported actually held overstated uniswapV3 0.01% $2,070,000 $215,646 9.6x uniswapV3 0.05% $73,600,000 $10,069,584 7.3x uniswapV3 0.30% $2,840,000,000 $111,513,855 25.5x uniswapV3 1.00% $14,800,000 $846,661 17.4x $2.84 billion in one pool on Base. Base's entire ecosystem TVL is a few billion dollars. That is what finally made me look — not a failing test, just a number too large to be true. Why it happens A v2 pool holds two piles of tokens and the price is the ratio between them. getReserves() returns the actual piles. Easy. A v3 pool concentrates liquidity into price ranges. It does not have "reserves" in the v2 sense. What it has is a liquidity value L at the current price P , and the standard way to make v3 math reusable is to compute the virtual reserves — the amounts a v2-style pool would need to behave identically right here: x_virtual = L / √P y_virtual = L × √P These are enormously useful. Feed them into the ordinary constant-product formula and you get correct swap outputs and correct price impact, which is why essentially every v3 integration computes them. They are also not tokens anyone owns . They describe the shape of the curve at the current price, not custody. Concentration is exactly the point of v3: a position spanning a narrow band behaves like a much larger v2 pool while holding far less capital. The 25x above is that leverage, showing up as a number I then mislabelled. My code did this: tvlUsd = 2 * reserveA * priceA // fine for v2, nonsense for v3 That line is corre