Price Impact Calculator
Model an AMM constant-product pool (x·y = k) end to end — solve for price impact, trade size, or pool depth, then see amount out, execution price, minimum received and the full slippage curve.
Holds Reserve X, Reserve Y and fee at your current inputs and sweeps trade size (Δx) — showing why impact accelerates as a trade approaches pool depth, and how the execution price degrades alongside it.
| Impact | Typical read |
|---|---|
| < 0.5% | Negligible — deep pool relative to trade |
| 0.5% – 2% | Low — routine for most pool/trade pairs |
| 2% – 5% | Moderate — worth comparing routes |
| > 5% | High — consider splitting the trade |
| Pool type | Typical fee |
|---|---|
| Stablecoin-optimized pools | ~0.01% – 0.05% |
| Standard token pairs (V2-style) | ~0.25% – 0.30% |
| Exotic / low-liquidity pairs | ~1.00% |
| Concentrated-liquidity tiers | 0.01% / 0.05% / 0.30% / 1.00% |
Trade Size ↑
Impact grows faster than trade size — doubling Δx more than doubles PI as the trade consumes a larger share of the pool's depth.
Pool Depth (x, y) ↑
Deeper reserves absorb the same trade size with far less impact — this is why liquidity depth matters more than the sticker fee for large trades.
Swap Fee ↑
A higher fee slightly shrinks the effective input reaching the curve, marginally lowering this formula's PI — but it raises the trader's total cost overall.
Splitting the trade
Breaking a large trade into smaller sequential fills against the same pool doesn't change the total impact of filling that total size — but spreading it across routes or time can.
What Is Price Impact?
Price impact is how much a trade moves the price inside an automated market maker (AMM) pool, purely because of the trade's own size relative to the pool's liquidity — separate from any external market movement. In a constant-product pool, every trade shifts the reserve ratio, and price impact quantifies that shift.
AMM Constant Product Formula
A constant-product AMM holds two reserves, x and y, whose product k stays constant (aside from fees, which slightly grow k over time). Every swap moves along this curve: adding Δx of Token X to the pool removes Δy of Token Y, keeping x'·y' ≈ k.
Price Impact Formula
Price impact is the fraction of the Token Y reserve removed by the trade, as a percentage. Using the constant-product relationship, this reduces to PI = 100 × Δx_eff / (x + Δx_eff), where Δx_eff = Δx × (1 − fee) — so PI depends only on trade size, pool depth in X, and the fee, not on the absolute size of reserve Y.
How to Calculate Price Impact
Choose the unknown above — Price Impact, Trade Amount, or Reserve X — enter the other two plus the swap fee, and the calculator rearranges the formula automatically. Reserve Y is always entered directly, since it's needed to convert the impact percentage into an actual amount received.
| Solve for | Rearranged formula |
|---|---|
| PI | PI = 100 × Δx(1−fee) / (x + Δx(1−fee)) |
| Δx | Δx = [x × PI/100 / (1−PI/100)] / (1−fee) |
| x | x = Δx(1−fee) × (100−PI) / PI |
Price Impact Formula Variables
| Symbol | Meaning |
|---|---|
| PI | Price impact, as a percentage of Reserve Y |
| x | Pool reserve of Token X before the trade |
| y | Pool reserve of Token Y before the trade |
| Δx | Amount of Token X being traded in (before fees) |
| Δy | Amount of Token Y received (derived, not entered) |
| k | Constant product, x · y, approximately preserved by every swap |
Price Impact vs. Slippage Tolerance
These are often confused but measure different things. Price impact is deterministic — it's exactly how much this specific trade moves this specific pool, calculable in advance from the reserves and trade size. Slippage tolerance is a safety margin the trader sets to protect against the price changing between submitting and confirming the trade (from other trades landing first, network latency, or front-running). The "minimum received" a wallet shows combines both: expected output minus your chosen slippage tolerance.
How Trade Size and Pool Depth Interact
Because PI = 100 × Δx_eff / (x + Δx_eff), impact is a function of the trade's size relative to the pool, not its absolute size. A 10 ETH trade is negligible against a 50,000 ETH pool but severe against a 50 ETH pool — which is why aggregators route large trades across multiple pools rather than one deep pool.
Price Impact Calculation Example
Δx_eff = 10 × (1 − 0.003) = 9.97 ETH
PI = 100 × 9.97 / (500 + 9.97)
PI = 1.9549% → Δy ≈ 17,594 USDC, execution price ≈ 1,759.4 USDC/ETH vs. a 1,800 USDC/ETH spot price
Frequently Asked Questions
Price impact is the guaranteed, calculable effect of your trade's size on this pool's price. Slippage tolerance is a buffer you set for price changes that happen between submitting and confirming the transaction, caused by other activity — not by your own trade.
Impact depends on Δx relative to reserve x, not on Δx alone. A larger reserve makes the same Δx a smaller fraction of the pool, so it moves the curve less.
Marginally, under this formula — a higher fee shrinks the effective input that reaches the pricing curve. But the fee itself is a separate, additional cost to the trader, so total cost still rises with fee.
k = x · y is the invariant a constant-product pool maintains. Because swap fees stay in the pool rather than being removed, k increases slightly with every trade — this growth is how liquidity providers earn fees over time.
No — this calculator models a simple constant-product pool (Uniswap V2-style) with a single fee tier. Concentrated liquidity spreads reserves across price ranges, and multi-hop routes combine several pools, both of which need pool-specific liquidity data to model accurately.
Variables
| Symbol | Quantity | Unit |
|---|---|---|
| Price Impact | Estimated price impact | % |
| Δy | Change in output token reserve | |
| y | Output token reserve before trade |
What it means
In AMMs (like Uniswap), trades change the reserves, affecting the price. Price impact is the percentage change in price caused by a trade. A larger trade has more impact. This is used to estimate slippage and to decide optimal trade sizes. Understanding price impact is essential for traders to minimise costs and for LPs to understand their risk.
Worked example
AMM Constant Product Price Impact – Two Detailed Examples
Real‑World| Parameter | Value |
|---|---|
| Pool Reserve (token Y) | 1,000,000 |
| Trade Output Amount | 10,000 |
| Parameter | Value |
|---|---|
| Reserve | 50,000 |
| Output | 5,000 |
Common mistakes
- AMM constant product: x*y = k, where x and y are token reserves.
- Δy: The change in token y reserve after a swap.
- Price impact: The percentage change in price due to the trade.
- Larger trades: Cause higher price impact.
Applications
AMM constant product price impact measures the percentage price change caused by a trade in a liquidity pool, based on the constant product formula (x*y=k). This is used to estimate slippage before executing a trade. Traders use it to assess the cost of larger trades and to choose pools with sufficient liquidity. Understanding price impact is critical for efficient trading on DEXs.
- Estimating slippage for trades on AMMs
- Choosing optimal pools for minimal price impact
- Managing trade size relative to pool liquidity
- Evaluating the efficiency of a trading route
- Educational understanding of AMM mechanics
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