= Write My Formula

Percentage formula generator

Create percentage formulas without mixing up the math.

Describe the percentage calculation, paste the cells involved, and get a formula with notes for percent formatting, absolute references, and edge cases.

Request

Formula request

2 guest tries left
Mode
Spreadsheet
Upgrade $9

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

Percentage formula generator for spreadsheet work.

Build percentage formulas for totals, changes, discounts, markup, tax, tips, or completion rates without having to remember whether the formula should divide, subtract, or multiply.

What this page gives you

  • A draft percentage formula for the exact calculation you describe.
  • A plain-English read of the numerator, denominator, rate, or comparison values.
  • Checks for percent formatting, locked references, blanks, and divide-by-zero cases.

When to use it

Use this page when a spreadsheet needs percent of total, percent change, discount, markup, tax, tip, or completion-rate math and you want the references spelled out before filling formulas down.

Do not paste a percentage formula across a live report until you confirm the cell format. Excel and Google Sheets store percentages as decimals, so multiplying by 100 and applying percent format can double-count the conversion.

Worked example

For revenue in B2 and the total revenue in B5, a percentage-of-total formula can show each category share.

=IFERROR(B2/$B$5,0)

The formula divides the category revenue by the locked total cell and returns 0 instead of an error if the total is blank or zero.

Check before you paste

  • Format decimal results as percentages instead of multiplying twice.
  • Lock total cells with dollar signs before filling formulas down.
  • Test blank totals and zero totals before using the formula in a report.

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

500 formula runs per month in this browser, early access pricing, and account access as it ships. Stripe redirects you back after payment.

Upgrade with Stripe