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ChatGPT runs a code-backed margin calculation on a structured export. You inspect the code and recalculate samples.
Get CSV, rules ready
Calculate in Python
Check and save pack
Use: You
Have ready: sales-line CSV (product, transaction ID, units, gross sales, discounts, returns, currency, approved variable costs) and sign convention, period cut-off, tax treatment, contribution-margin definition.
Stop if upload permission is absent. Verify date, currency, completeness and the supplied rules; do not replace missing rules with guesses. Keep inputs in an access-controlled local draft.
Use: ChatGPT
Only the approved input package from step 1: attach the CSV, paste the rules. ChatGPT shows Python code, row counts, assumptions and exception rows.
What to paste into the tool
Task: Produce a draft product-level margin table with a row-level calculation trail and missing-cost/return exceptions. Inputs: [ATTACH: the approved sales, discount, return and cost CSV from step A-1] [PASTE: sign convention] [PASTE: contribution-margin definition] [PASTE: period cut-off] [PASTE: approved tax treatment, including whether sales and costs include or exclude tax]. Use only these inputs. Show the Python used and a row-level audit trail with source IDs. Apply only the supplied contribution definition. Keep return and discount signs explicit. Do not treat contribution as net profit. Do not allocate overhead unless the owner supplies a rule. Keep currencies separate; use 'not stated' where costs or treatment are absent. Flag zero or negative net sales before computing margin percentages. Never silently drop or repair rows. Report missing facts as 'not stated'. Do not access accounts or external sources, send messages, post entries, change the master ledger, sign, publish or pay. Produce a draft for human review only.
Use: You
Check the output, correct or reject it; save locally, marked draft. Product totals reconcile to included sales rows and approved costs with the agreed formulas.
Recalculate a normal sale, discounted sale, return, zero-sales row and missing-cost item. Zero denominators: 'not stated'. Do not send, sign, pay, publish, post journals or update master records.
Copilot in Excel suggests formulas from synthetic sample columns only. You apply checked formulas locally to the real draft.
Get CSV, rules ready
Suggest formulas
Test, build, check
Use: You
Have ready: sales-line CSV (product, transaction ID, units, gross sales, discounts, returns, currency, approved variable costs) and sign convention, period cut-off, tax treatment, contribution-margin definition.
Stop if upload permission is absent. Copilot must not modify the workbook or make a finance decision.
Use: Copilot in Excel
Ask in chat mode for formulas and explanations using synthetic sample rows and column names only, no real figures.
What to paste into the tool
Task: Suggest spreadsheet formulas and test cases for a private draft worksheet, not a finance decision. Inputs: [PASTE: 5-10 synthetic example rows, no real products or amounts] [PASTE: column names] [PASTE: approved sign convention and contribution definition] [PASTE: period cut-off and approved tax treatment]. Use only these inputs. Apply only the supplied contribution definition. Keep return and discount signs explicit. Do not treat contribution as net profit. Do not allocate overhead unless the owner supplies a rule. Keep currencies separate; use 'not stated' where costs or treatment are absent. Flag zero or negative net sales before computing margin percentages. Explain references, date boundaries, sign handling and error conditions. Give formulas as text, with sample expected results; do not edit files. Missing inputs must produce a 'not stated' note or an explicit exception. Do not choose accounting policy or recommend action. Do not send, post, sign, publish or pay.
Use: You
Test each formula on synthetic normal and edge cases before applying it. Build the draft yourself; product totals must reconcile to rows and approved costs.
Zero denominators: 'not stated'. Save locally, marked draft. Do not send, sign, pay, publish, post journals or update master records.
You do all the arithmetic first. Claude only summarises a small, checked text note.
Calculate by hand, write note
Summarise the note
Check and save pack
Use: You
Have ready: sales-line CSV (product, transaction ID, units, gross sales, discounts, returns, currency, approved variable costs) and sign convention, period cut-off, tax treatment, contribution-margin definition.
Stop if upload permission is absent. Calculate net sales and contribution by hand; reconcile product totals; note low margins and missing costs.
Use: Claude
Only the approved input package from step 1: the checked note, not the data file. Claude summarises it and lists open questions, no recalculating.
What to paste into the tool
Task: Write a factual product-margin review note quoting checked totals and exceptions, without price-change or product-withdrawal recommendations. Input: [PASTE: the human-checked note from step C-1]. Use only this note. Preserve every amount, unit, date, label and source ID exactly. Do not recalculate, infer missing facts or add a judgement. Apply only the supplied contribution definition. Keep return and discount signs explicit. Do not treat contribution as net profit. Do not allocate overhead unless the owner supplies a rule. Keep currencies separate; use 'not stated' where costs or treatment are absent. Flag zero or negative net sales before computing margin percentages. Say 'not stated' for missing information. Separate facts from open questions. Do not draft an external message or instruct anyone to act. Do not access accounts, send, post, sign, publish or pay. Return internal draft text only.
Use: You
Check every sentence and number against your note; remove unsupported interpretations and keep not-stated facts visible. Product totals must reconcile.
Zero denominators: 'not stated'. Save locally, marked draft. Do not send, sign, pay, publish, post journals or update master records.
Best when: A structured export needs repeatable batch calculations you can inspect.
What it does: ChatGPT calculates in code; you recalculate samples.
Strong at: Shows the Python code and row-level audit trail.
Limit: Free plan limits file uploads and data analysis.
Free plan: Yes, limited (file uploads, data analysis)
Best when: You want to build and own the formulas.
What it does: Copilot in Excel suggests formulas; you build and test them.
Strong at: Explains formulas and gives synthetic test cases.
Limit: On iPhone and Android, chat mode only.
Free plan: Paid plan needed
Best when: You want to do all the arithmetic yourself.
What it does: You calculate by hand; Claude summarises the checked note.
Strong at: Preserves every amount, date and source ID exactly.
Limit: Usage is capped in 5-hour and weekly windows.
Free plan: Yes, limited (usage capped in 5-hour and weekly windows)
Before you paste into any AI tool, remove any confidential information. Put it back at the end.
Deciding between ChatGPT and Claude for this? See the comparison.
Never paste credentials or full payment details.
Confirm authorised inputs and rules before use.
Independently recalculate a normal sale, discounted sale, return, zero-sales row and missing-cost item. Tie product totals to transaction totals by currency; verify percentages use the approved denominator.
Reconcile completeness and totals, preserve open questions, and save only a draft.
Check the result against your original inputs. Approve it before sharing or acting.
Based on official product documentation checked on 2026-10-29.