The Excel-AI gap closed in 2026. Multi-driver campaign forecasts, channel attribution, LTV math, and SaaS reporting that took half a day now ship in under an hour with Claude in Excel: Opus 4.7 inside Microsoft 365 Copilot, ChatGPT Plus via the desktop app, or Claude on the web for paste-and-prompt. Whatever the tool, the prompt patterns below are what separates formulas you paste from formulas you rewrite.
Pair this with the cluster hub Claude in Microsoft 365 for Marketers for the full setup detail and the compare spoke Claude in MS 365 vs ChatGPT in Excel for the head-to-head decision.
Six Marketer Workflows in Excel
The tasks where Claude in Excel earns the time-saving claim. Each compresses a half-day spreadsheet build into under an hour when the prompt patterns below are applied.
Build a 24-month campaign forecast with assumption cells for spend, CTR, conversion rate, AOV, and repeat rate. Claude returns the formulas tied to each assumption cell. Edit one input, the whole forecast updates. Compresses a half-day model build into 25 minutes.
Split monthly revenue across paid, organic, partnerships, and direct using a chosen attribution model (last touch, linear, or position-based). Claude generates the SUMPRODUCT formulas, time-decay weights, and the reconciliation total against blended revenue.
Paste a cohort table (signup month rows, retention month columns). Claude returns the LTV formula stack: per-cohort retention curve, average revenue per active customer, cumulative LTV by month 12 and 24, and the variance band across cohorts.
Take ad-spend total, paid-acquired customers, total new customers, and total marketing spend. Claude returns paid CAC (spend / paid customers), blended CAC (total spend / all customers), and the marketing-efficiency ratio versus revenue contribution.
Paste a Stripe-style invoice or subscription export. Claude generates monthly MRR, churn rate, expansion MRR, contraction MRR, and net revenue retention formulas that respect cancelled-versus-paused subscriptions and proration.
Paste platform exports for LinkedIn, X, Threads, Instagram side by side. Claude returns the engagement-rate formula per platform (engagement events / impressions), normalizes against follower count, and surfaces the top-performing post per platform per month.
Prompt Patterns That Produce Working Formulas
Six prompt patterns that separate Claude responses you paste directly from responses you rewrite. Build them into a reusable prompt block at the top of every Excel-Claude session.
Anchor cell ranges explicitly
"Assumption inputs are in C5:C12 (spend, CTR, CVR, AOV, repeat rate, retention curve, etc.). Output a 24-column monthly forecast grid in F5:AC12." Cell ranges in the prompt produce formulas you paste without rewrite.
Specify formula style
"Use SUMPRODUCT not array formulas, prefer readable named ranges over indirect references, no volatile functions like OFFSET or INDIRECT, finance-review-ready style." Style guidance prevents Claude defaulting to dense one-liners.
Wrap divisions in error handling
"Wrap every division in IFERROR returning 0, use IFNA on lookups, no #REF! or #DIV/0! in the output grid." Critical for sales-leadership review where any visible error tanks credibility.
Constrain sheet structure
"One sheet, no helper sheets, all formulas resolve in 24 rows and 12 columns max. Header row in B5:M5, data in B6:M28." Without this, Claude proposes multi-sheet helpers that nobody reviews.
Pin the question the chart answers
"Generate a chart specification answering: which channel drove the 30 percent revenue lift between month 6 and month 9? Show channels stacked, highlight the lift months." A pinned question produces a chart finance signs off on.
Force assumption traceability
"Every output cell traces back to a labeled assumption cell. No hard-coded numbers in the output grid. List the assumption-cell-to-output-cell map at the bottom of the sheet." This is what separates a forecast a CFO trusts from one they reject.
Three Ways to Run Claude in Excel
Microsoft 365 Copilot with the model picker
The tenant-resident path. Claude Opus 4.7 has been a model option in the Copilot pane in Excel since April 16 2026. Tenant admin enables Anthropic models for the organization, end user picks Claude Opus 4.7 from the model selector, data stays inside the tenant on Azure infrastructure. Right path for any marketing team where data governance is a real constraint.
ChatGPT desktop app reading the active workbook
The fastest-setup path for solo marketers without Microsoft 365 Copilot. The ChatGPT desktop app on macOS or Windows reads the active Excel workbook with a permission prompt. Pasted ranges work too. Data leaves the Microsoft 365 tenant boundary on the upload: fine for non-sensitive workbooks, not fine for customer-revenue or paid-channel data without an IT review.
Claude on the web for paste-and-prompt
The lowest-friction path. Sign in at claude.ai, paste the workbook range or upload an .xlsx, and prompt for the formula or chart specification. Works on any plan including the free tier. Same data-boundary point as the ChatGPT desktop app: fine for non-sensitive marketing workbooks, requires the IT data-handling review for customer or revenue data.
When the ROI Calculator Beats the Full Model
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Use the calculator as the sanity check before committing to a full Excel build. Or as the published artifact that lets prospects price the work themselves on a discovery call. The Excel build is the operational tool; the calculator is the conversational tool. Both exist for a reason.
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