Liquidity Pool Share Calculator

Every AMM deposit forces a choice: put in too little of one token and the pool rejects you, put in too much and you waste capital. This calculator takes the current pool reserves and your deposit amount for Token A and tells you exactly how much Token B the constant-product formula requires. On a 500 ETH / 1 000 000 USDC pool, depositing 5 ETH requires 10 000 USDC — the ratio is locked, not negotiable. That figure appears the moment the first Load Sample click lands.

Once both sides are known the tool computes your pool share: how large a slice of the liquidity pool you will own after the deposit. Owning 0.9901% of a pool means you collect that fraction of every swap fee the pool earns and the same fraction of any impermanent loss it incurs. There is an optional USD value panel: fill in both token prices and the deposit position is priced in dollars immediately.

Worked Example: ETH / USDC at a 2 000 Price

Load Sample fills the pool reserves with 500 ETH and 1 000 000 USDC and the deposit field with 5 ETH. The required USDC output is 10 000, computed as 5 × 1 000 000 / 500 = 10 000. Your share of the new pool (505 ETH / 1 010 000 USDC) is 5 / (500 + 5) = 0.9901%. Add ETH price $2 000 and USDC price $1 in the optional fields and the deposit value reads $20 000 — 5 × $2 000 plus 10 000 × $1.

The Constant-Product Formula Behind the Required Amount

A Uniswap-style pool maintains x × y = k at all times, where x and y are the reserves of the two tokens. A deposit must keep the ratio unchanged: depositB = depositA × poolB / poolA. Any other ratio shifts the on-chain price, so the pool contract rejects it. When you enter only your Token A amount the calculator solves that equation and fills the Token B field. The I know both amounts mode accepts any two figures and flags an imbalance warning when the two sides imply pool-share percentages that differ by more than 1%.

For weighted pools (Balancer-style 80/20 or 60/40) the share formula switches to a geometric mean: share = shareA^wA × shareB^wB, where wA + wB = 1. Select the matching weight preset before entering reserves to use the right formula.

When Not to Use This Tool

• Swap fees: Uniswap v2 charges 0.3% per trade; Uniswap v3 stable pools charge 0.05%. The tool shows the pre-fee deposit ratio; fees are deducted from incoming swaps, not from LP deposits directly.
• Impermanent loss: your share percentage is fixed at deposit time. If the price ratio moves after you deposit, the pool rebalances and your position may be worth less than simply holding both tokens. The sibling Impermanent Loss Calculator on this platform quantifies that risk separately.
• Concentrated liquidity (Uniswap v3 range positions): v3 lets LPs concentrate capital in a price range; the deposit ratio depends on the chosen tick boundaries, not just the current price. This tool covers full-range 50/50 and weighted-pool deposits only.
• Minimum share display: shares below 0.0001% are shown as < 0.0001% rather than rounding to zero, because a very small share is still a real position.