---
title: "Which AI Chat Can Estimate Slippage from Order-Book Depth?"
description: "See Trade Inc Chat compare a hypothetical 40-lot purchase with a price-limited fill—and explain why missing depth makes the rest of an order unpriceable."
author: "Trade Inc Research"
published_at: "2026-10-10T03:11:29Z"
updated_at: "2026-10-10T03:11:32Z"
canonical: "https://tradeinc.app/en/blog/ai-chat-order-book-depth-fill-cost"
tickers: []
citations: ["https://tradeinc.app/en","https://www.investor.gov/introduction-investing/investing-basics/how-stock-markets-work/types-orders","https://cdn.sanity.io/images/eybaj6wm/production/dba3f329de095f8f6a355b029c5ff5f40321addf-1280x720.jpg"]
---

# Which AI Chat Can Estimate Slippage from Order-Book Depth?

See Trade Inc Chat compare a hypothetical 40-lot purchase with a price-limited fill—and explain why missing depth makes the rest of an order unpriceable.

Trade Inc Chat can help calculate the weighted purchase price from several order-book levels you supply. In our actual Pro-account walkthrough, it compared a hypothetical 40-lot purchase with a price-limited partial fill, separated fees from price slippage, and refused to invent a price when the supplied depth ran out. This is a calculation aid—not an execution quote or a broker order ticket.

## Key takeaways

- The cheapest offer is not the average price of a larger purchase. Our 40-lot example averages Rp1,005, although the first offer is Rp1,000.
- A Rp1,005 cap buys only 30 of the requested 40 lots in the fixed example. A smaller cash outlay does not mean the same quantity became cheaper.
- When a 70-lot request exceeds the 60 lots supplied, the cost of the missing 10 lots is unknown.
- These are invented inputs, not current IDX quotes, a stock recommendation or a prediction of actual fills.

Disclosure: this guide is published by Trade Inc. We tested the signed-in Pro Chat interface on 10 October 2026. This does not establish availability on every plan. The [public product page](https://tradeinc.app/en) describes custom analysis; the screenshots below document this particular calculation workflow.

## Why a best-offer price is not a purchase-cost estimate

Suppose the first offer shows Rp1,000, but only 10 lots are available there. Multiplying a 40-lot request by Rp1,000 assumes another 30 lots exist at that price. Our example deliberately removes that shortcut.

As a general order-type distinction, a buy limit restricts the acceptable price, while a market order does not guarantee an execution price. [Investor.gov explains those concepts](https://www.investor.gov/introduction-investing/investing-basics/how-stock-markets-work/types-orders). That US investor-education source is not evidence of the order types your IDX broker offers. Here, “through the book” simply means a mathematical sweep of the supplied asks from lowest to highest.

## 1. Give Chat the levels, units and fee assumption

Open Chat, enter the following assumptions, leave the observed response mode at **Cepat**, and press the upward-arrow **Kirim** button. We used these fixed inputs:

| Offer price per share | Available lots | Shares, assuming 100 per lot |
| --- | ---: | ---: |
| Rp1,000 | 10 | 1,000 |
| Rp1,005 | 20 | 2,000 |
| Rp1,010 | 30 | 3,000 |

We asked for a 40-lot comparison, a Rp1,005 price cap in the second case, and an assumed buy fee of 0.15% of filled gross value. That fee is illustrative, not a claim about any broker's tariff. We explicitly excluded market-data retrieval, Screener creation, backtesting and order execution.

![Trade Inc Chat composer with hypothetical ask levels, 40-lot comparison, fee assumption and Send arrow](https://cdn.sanity.io/images/eybaj6wm/production/a7fadb0f92ed0e166f3258f049fc4e62d6164cf2-1004x350.jpg)

*Actual input before pressing Kirim. The prompt requests code, but this capture does not prove how the calculation was executed; our claim is limited to the visible answer and independently checked arithmetic.*

## 2. Check the fill quantities before comparing costs

Chat returned both cases in one table:

![Actual Chat table comparing a 40-lot sweep with a 30-lot capped fill and ten unfilled lots](https://cdn.sanity.io/images/eybaj6wm/production/dba3f329de095f8f6a355b029c5ff5f40321addf-1280x720.jpg)

*The answer separates gross purchase value, average price, price slippage and the assumed fee. It also warns that the two cases buy different quantities.*

| Measure | Sweep 40 lots | Cap at Rp1,005, request 40 lots |
| --- | ---: | ---: |
| Lots filled at Rp1,000 / Rp1,005 / Rp1,010 | 10 / 20 / 10 | 10 / 20 / 0 |
| Filled / unfilled lots | 40 / 0 | 30 / 10 |
| Gross value | Rp4,020,000 | Rp3,010,000 |
| Average price, before fees | Rp1,005 | Rp1,003.33, rounded |
| Price slippage versus Rp1,000, on filled shares | Rp20,000 | Rp10,000 |
| Assumed fee, 0.15% | Rp6,030 | Rp4,515 |
| Total including that fee | Rp4,026,030 | Rp3,014,515 |

The first gross value is `(1,000 × 1,000) + (2,000 × 1,005) + (1,000 × 1,010) = Rp4,020,000`. Divide by 4,000 shares for Rp1,005. Compared with Rp1,000, that is 0.5% price slippage before fees. Add Rp6,030 for the stated total.

The capped case stops before Rp1,010. Its Rp3,014,515 total covers 3,000 shares, not 4,000. It cannot be described as saving the difference while acquiring the same position. We independently recalculated both rows; rounding applies only to the displayed average in the second row.

## 3. Ask what happens when the supplied depth runs out

Our follow-up changed the request to 70 lots without a price cap, while keeping the same three levels. Chat reported 60 known lots for **Rp6,040,000 before fees**, with 10 lots unfilled in this model. It did not assign a price to the missing quantity.

![Chat follow-up showing sixty known lots, Rp6,040,000 gross cost and an unknown cost for the remaining ten lots](https://cdn.sanity.io/images/eybaj6wm/production/1c3f9975fcd4321a4888467e0a57ee3a09882ec3-1280x720.jpg)

*Actual follow-up and answer. The quoted cost covers only the supplied 60 lots, excludes fees, and is not a total for the requested 70 lots.*

This boundary is useful: do not let a neat average hide missing liquidity. More depth would require more input, not an invented fourth offer.

## What this demonstration does not establish

The calculation assumes every supplied lot remains available. Real quotes can change, competing orders can consume liquidity, and fills can arrive at different times. The model does not represent queue priority, replenishment, latency, auctions, broker-specific order handling or additional charges. It neither forecasts market impact nor guarantees a partial fill will occur exactly as shown.

No live order-book feed was tested here. For the separate task of inspecting executed trades beside displayed liquidity, see our [Running Trades and order-book walkthrough](https://tradeinc.app/en/blog/idx-running-trades-large-trade-order-book). For a different denominator, the [position-versus-daily-volume guide](https://tradeinc.app/en/blog/ai-chat-idx-position-trading-volume) explains why historical daily turnover is not the quantity available now.

## Who benefits—and who may not need Chat

This fits researchers who want to change quantities, price caps or assumptions conversationally and inspect the explanation alongside the numbers. A spreadsheet or calculator is sufficient for a one-off three-level weighted average. A broker's own interface and applicable rules remain necessary for any real order; this guide demonstrates no trade-placement capability.

The practical takeaway is to ask for three outputs separately: **quantity filled, cost of that quantity, and quantity still unpriced**. Trade Inc Chat handled those distinctions in this worked example. That is more informative than multiplying the whole request by the best offer, but it remains an assumption-based calculation, not an execution promise.


[1]: https://tradeinc.app/en "Trade Inc — custom analysis"
[2]: https://www.investor.gov/introduction-investing/investing-basics/how-stock-markets-work/types-orders "Investor.gov — Types of Orders"
[3]: https://cdn.sanity.io/images/eybaj6wm/production/dba3f329de095f8f6a355b029c5ff5f40321addf-1280x720.jpg "Original Trade Inc Chat demonstration, 10 October 2026"