= Write My Formula

Date formula generator

Date formulas that do not return 45678.

Type what you are trying to figure out, such as business days between two dates or rows more than 30 days overdue. Get a formula plus a short note on the input format it expects.

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Formula request

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Mode
Spreadsheet
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Purpose-built inputs

A focused workflow for everyday spreadsheet work.

Structured formula builder

Task, table context, target range, and function hint keep the request specific.

Write / Explain / Fix modes

Generate a new formula, translate a pasted one, or diagnose common syntax issues.

Excel and Sheets toggle

Compatibility notes call out modern functions and platform-specific behavior.

Formula-bar output

The result is formatted for scanning and placed next to a copy button.

Common formulas

Pick the formula you came for.

Percentage formulas

Build percent of total, percent change, discount, markup, tax, tip, and completion-rate formulas.

Date formulas

Create due dates, workday counts, month-end dates, date differences, and overdue checks.

FILTER formulas

Return matching rows for status, region, date, text, and threshold conditions.

Text formulas

Split, extract, join, trim, clean, and replace text from messy imported cells.

Data validation formulas

Block bad IDs, duplicate values, missing fields, and invalid entries with custom TRUE/FALSE rules.

XLOOKUP formulas

Return matching values with separate lookup and return ranges.

INDEX MATCH formulas

Build flexible lookup formulas for left lookups, two-way lookups, and older Excel files.

SUMIFS formulas

Total rows that match status, date, category, customer, or region rules.

Use case

Date formula generator for spreadsheet work.

Build date formulas for deadlines, workday counts, month-end reporting, renewal dates, age calculations, and overdue status checks.

What this page gives you

  • A draft date formula matched to the deadline or date comparison you describe.
  • A plain-English read of which cells are dates, offsets, holidays, or cutoff values.
  • Checks for date formatting, text dates, weekends, holidays, and month boundaries.

When to use it

Use this page when spreadsheet work depends on dates that should update automatically, such as due dates, billing cycles, workday counts, aging reports, or overdue flags. Tell the tool whether you are in Excel or Google Sheets because date parsing and some function behavior can differ.

Do not paste date formulas broadly until you confirm the source cells are real date values. Excel and Google Sheets can display dates while still storing imported values as text, which changes formula behavior.

Worked example

For a start date in A2 and a company holiday list in F2:F20, a workday formula can calculate a due date 10 business days later.

=WORKDAY(A2,10,$F$2:$F$20)

The formula starts from A2, moves forward 10 workdays, skips normal weekends, and also skips any holiday dates in the locked holiday range.

Check before you paste

  • Confirm that source cells are stored as dates, not text.
  • Format serial-number results as dates before sharing the sheet.
  • Test the formula around weekends, holidays, and month boundaries.

Upgrade when the work piles up

Keep going when the sheet gets complicated.

Try twice as a guest. Free accounts get 3 runs per week plus a monthly product email. Upgrade when formula work becomes a recurring part of the week.

Founding access

$9

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