Partial Fill Calculator: Average Price, Fees, and Remaining Shares
A partial fill leaves two separate questions: what has already traded, and what can still trade. Add the confirmed execution quantities, calculate their quantity-weighted price, and count each incurred fee once. Then subtract filled shares from the original order quantity. That subtraction gives the unfilled amount, not proof that the remainder is still working or has been canceled. Before changing or replacing an order, match the execution log to the current ticket and verify its remaining status with your broker. The calculator below reconciles one order in one currency; it does not predict another fill or choose your next trade.
Reconcile the executions before touching the remainder
Enter executed shares and execution prices, not displayed quotes, your limit price, or an expected future fill. A single market order can execute in pieces at different prices, as Investor.gov explains in its updated order-types bulletin. Our weighted-average arithmetic is derived below; the regulator does not endorse this calculator.
Partial fill calculator
Hypothetical USD example preloaded. Use one currency throughout. No account connection; nothing here submits an order.
Enable JavaScript to calculate, or use the formula below.
Cash amount means money paid for a buy or net proceeds for a sell. It is not profit, a tax basis, margin usage, or the market value of your holdings. No assumed fees for future fills are included.
Why the weighted price is not the simple average
For each confirmed fill, multiply quantity by price. Add those amounts and divide by total filled shares. A 40-share execution must carry more weight than a 30-share execution. Averaging the two displayed prices equally treats unequal executions as equal-sized trades.
Weighted fill price = sum of (filled shares × execution price) ÷ total filled shares. Entered fees are kept separate. Buy cash paid equals gross execution amount plus entered fees. Sell net proceeds equals gross execution amount minus entered fees. The fee-adjusted per-share result divides that cash amount by filled shares.
In the invented example, 40 shares at $50.00 and 30 at $50.20 produce 70 filled shares and $3,506 of gross execution value. The weighted price is $50.085714, not $50.10. With $2.50 of total entered fees, buying costs $3,508.50, or $50.121429 per filled share. Selling the same quantities produces $3,503.50, or $50.05 per filled share. Neither number measures a gain or loss.
Precision matters: the displayed average rounds to six decimal places, but the calculation uses unrounded inputs. Use the execution-level precision available in your records. A small discrepancy can be rounding; a large one calls for reconciliation, not an invented adjustment to make totals match.
What does your remaining-order status allow you to conclude?
| Record you can verify | Meaning of the remainder | Next check |
|---|---|---|
| 70 of 100 filled; 30 confirmed working | 30 unfilled and still working at the recorded moment | Check current ticket terms and any newer execution before changing it. |
| 70 filled; cancellation requested | 30 unfilled in your entered log; current working amount is unknown | Obtain final status and updated executions. Do not treat the request receipt as cancellation. |
| 70 filled; remaining 30 confirmed canceled or expired | 30 remain historically unfilled; working remainder is zero | Reconcile final executions and fees before considering a separate instruction. |
| 100 of 100 confirmed filled | No unfilled quantity on this ticket | Check holdings and any other open tickets independently. |
| Rows total more than the order quantity | The entered records do not reconcile | Stop. Check duplicates, amendments and whether rows belong to different orders. |
| No confirmed executions | No average execution price exists | Verify actual order status; a blank execution list is not proof of a failed order. |
The SEC's online-trading cautions warn against assuming an order failed or that a cancellation receipt proves it was canceled. This older source is used only for those operational warnings, not its historical settlement or pricing examples. If a stop instruction caused the partial exit, use the stop-trigger and cancellation checks alongside this execution log.
Count fees once, and leave future fills out
Use the fee column only for charges attributable to that row. Put a separate charge already incurred for the order into the additional-fees field once. If the broker reports one aggregate fee, enter zero in the individual rows and place the aggregate amount in the additional field. Do not put the aggregate fee in every row.
Zero means you have deliberately entered no charge for that field. A blank means missing information, so the tool clears its results. If fees have not been finalized, label your reconciliation provisional outside the calculator and revisit it when the confirmation arrives. Costs for a later execution belong in the calculation only after that execution and its costs are known.
Do not add the bid-ask spread or slippage again as a cash fee. They can affect the execution price already entered. This tool does not measure execution quality against an earlier quote, fund expenses, currency conversion, taxes, financing or stock-borrow costs. Reconcile those separately where they apply.
IOC, FOK and AON do not mean the same thing
An immediate-or-cancel instruction can accept a partial execution and cancel what cannot execute immediately. Fill-or-kill requires the whole quantity immediately. All-or-none also prevents a partial fill but does not impose the same immediate deadline. A GTC instruction has a broker-defined life; it is not perpetual. FINRA's time-in-force guide explains these distinctions. Availability and handling depend on the firm and product; verify the actual ticket rather than inferring its rules from an abbreviation.
This is a record check, not a recommendation to switch order types. Before a genuinely new instruction, review the price-control versus execution-priority trade-off. If the problem is now how much risk a confirmed position creates, use the Position Size Calculator with actual position data, not the unfilled amount on an old ticket. The Risk Management Decision Hub routes broader exposure questions.
When to stop using the simplified calculation
Stop and reconcile with your broker if executions use different currencies, the ticket was amended without a clear cumulative quantity, records contain reversals or corrected trades, or the confirmed status conflicts with a newer fill. The tool accepts fractional shares and up to 20 positive execution rows for a single consistent order. Remove a row only when it is not a confirmed execution in the record being reconciled.
Keep the order ID and version, symbol, side, original quantity, timestamps with time zone, each execution's quantity and price, fee statement, and final remaining status together. The copyable note summarizes only the numbers entered here. Add identifying details to your own private record; this page does not need an account number.
Primary sources and further reading
- Investor.gov: Understanding Order Types, updated August 18, 2026. Used for differing execution prices and broker-policy scope.
- FINRA: Time Parameters and Qualifiers on Stock Orders, updated July 17, 2024. Used only for order-duration and partial-fill qualifiers.
- SEC: Tips for Online Investing, historical page. Limited to duplicate-order and cancellation-confirmation cautions.
Reviewed September 12, 2026. Educational arithmetic and U.S. stock-order terminology, not investment advice or a broker instruction. No execution, return, tax outcome or ability to cancel is guaranteed. Your broker's current confirmation and applicable rules control.
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