Free research tool
Slippage Calculator: Order Book and Average Fill
The best price may cover only part of an order. Paste asks for a buy or bids for a sell to see how a hypothetical order walks the book, what its average fill costs and whether the supplied depth is enough.
Estimate price impact
Your scenario
$60,050.00 average buy fill price
- Quantity available for this fill
- 0.3
- Quantity left unfilled
- 0
- Best entered ask
- $60,000.00
- Average buy price of the filled portion
- $60,050.00
- Slippage versus best entered price
- 0.083333%
- Trading fee on the filled portion
- $18.015
- Cost of the filled portion, including fee
- $18,033.015
Your entered asks are sorted from lowest to highest and consumed until the quantity or supplied depth runs out. The book is assumed unchanged. Hidden orders, cancellations, latency, tick rules and nonlinear venue fees are excluded. Use this flat-fee model for crypto books; Polymarket fees need the separate fee calculator.
Continue in Vultax
Read the depth with its source time
Vultax's public order-book page compares responding Bitcoin venues with bid, ask, spread and reported depth. Open the crypto workspace from that page for the corresponding market view.
Worked example
Buying 0.3 BTC through asks of 0.1 BTC at $60,000, 0.1 at $60,050 and 0.2 at $60,100 fills at a $60,050 average. That is 0.083333% above the best ask. The $18,015 trade value plus a 10 bps fee costs $18,033.015.
Filled trade value = sum of price × quantity taken at each level. Average fill = filled value ÷ filled quantity. Buy slippage = (average − best ask) ÷ best ask; sell slippage = (best bid − average) ÷ best bid.
Separate spread from depth slippage
Spread is the gap between the best bid and ask. This tool measures how far an order's average fill moves from the best available price on the side it consumes. It does not compare the average with the midpoint, so it does not include crossing half the spread in the slippage percentage.
A book is a snapshot of orders that can be cancelled before you arrive. The calculation assumes all entered levels remain available while the order fills. Use source times when comparing venues.
Missing depth leaves part of an order unpriced
If the supplied levels cannot cover the quantity, the result reports a partial fill and leaves the remainder unfilled. Its dollar totals then describe only the filled portion. It never invents liquidity beyond the last supplied level.
This is a dollar-quoted book with a flat fee on filled value. Polymarket's nonlinear share fee should be calculated separately at the relevant fill prices; exchange tick sizes and minimum order amounts are not modelled.
Questions about this calculation
- Is this an AMM slippage-tolerance calculator?
- No. This tool consumes entered order-book levels to estimate a fill. It does not model a liquidity-pool curve, an AMM swap or a percentage tolerance that protects an on-chain transaction.
- Can I use the best ask for the whole order?
- Only if enough quantity is available at that ask and it remains there when you trade. Otherwise the order consumes higher asks and the average purchase price rises. For a sale it consumes lower bids.
- What happens if my order is larger than the pasted book?
- The calculator stops at the available depth and reports the unfilled quantity. All cost, fee and average-price figures then apply to the filled portion, not to the whole requested order.