Top 5 Percentage Formulas in Business

These five percentage formulas show up everywhere—from pricing and promotions to reporting and forecasting. Below you’ll find clear definitions, Excel/Sheets snippets, worked examples, common mistakes, and quick links to calculators.

Formula

1) Percentage Change (Increase/Decrease)

(New − Old) ÷ Old × 100

Use it to measure:

  • Sales growth
  • Cost changes
  • Traffic/KPI shifts
  • Price movements

Example: Revenue grows from $80k to $95k. (95,000 − 80,000) / 80,000 × 100 = 18.75%.

Excel/Sheets: =(New-Old)/Old then format as % (e.g., =(C2-B2)/B2).

Common mistakes: using New as the denominator; pasting values as text; not handling negatives (declines show as negative %).

Try the Percentage Increase Calculator for instant results. For multi-period growth use CAGR rather than simple change.

Formula

2) Discount (Sale Price)

Sale Price = Original × (1 − Discount%)

Use it to plan:

  • Promotions
  • Markdowns
  • Clearance
  • Stacked offers

Example: $200 item at 25% off → 200 × (1 − 0.25) = $150. Stacked 20% then 10% equals 28% total, not 30%.

Excel/Sheets: =Original*(1-Discount%) (e.g., =B2*(1-C2)).

Common mistakes: adding percentages (20%+10% ≠ 30%); discounting the tax-included price when you intended pre-tax; not setting a minimum margin.

Use the Discount Calculator to model percent-off, fixed-amount-off, and stacked discounts with before/after-tax totals.

Formula

3) Margin

Margin% = (Price − Cost) ÷ Price × 100

Use it for:

  • P&L reporting
  • Profitability
  • Price targets
  • Mix analysis

Example: Cost $60, Price $100 → Margin = (100 − 60) / 100 = 40%.

Excel/Sheets: =(Price-Cost)/Price then format as %.

Common mistakes: confusing margin with markup; forgetting shipping/fees in cost; calculating on tax-inclusive prices when reporting is ex-tax.

Need the inverse (price from margin)? The Markup & Margin Calculator solves for price, margin, or markup in one click.

Formula

4) Markup

Markup% = (Price − Cost) ÷ Cost × 100

Use it to:

  • Build sell prices from cost
  • Wholesale price lists
  • Retail keystone rules

Example: Cost $100 with 50% markup → Price = 100 × (1 + 0.5) = $150. Margin at $150 is 50/150 = 33.3% (not 50%).

Excel/Sheets: =Cost*(1+Markup%) (e.g., =B2*(1+C2)).

Common mistakes: assuming markup% = margin%; applying markup to tax-inclusive costs; not updating markup when input costs change.

Convert cleanly between the two with the Markup & Margin Calculator.

Formula

5) Share of Total

Share% = Part ÷ Total × 100

Use it for:

  • Category share
  • Channel mix
  • Budget allocation
  • Department cost split

Example: Channel A spends $35k of $120k total → 35,000 / 120,000 × 100 = 29.17%.

Excel/Sheets: =Part/Total then format as % (e.g., =B2/C2).

Common mistakes: totals that exclude refunds/fees; mixing periods; dividing by zero; using filtered totals that omit hidden rows.

For spreadsheet tips, see Percentage Formula in Excel/Sheets. Planning goals? Try the Savings Goal Calculator or model repayments with the Loan Repayment Calculator.