Quick guide
How to use this calculator
- Enter values from one real situation and keep currencies, quantities, and periods consistent.
- Use the optional fields only when they apply; the calculator will keep every entered adjustment visible in the result.
- Compare the component outputs and read the calculator-specific boundary before making a purchase or plan.
Calculation method
Calculation method
Unit-price change = ((new price ÷ new quantity) ÷ (old price ÷ old quantity) − 1) × 100%.
Entered fixed decimals use exact rational arithmetic wherever the task involves money, ratios, or allocations. Whole packages, tables, seats, and items round only where the real task requires indivisible units.
Worked example
Worked example
A package changing from 500 g at 5.00 to 450 g at 5.20 raises unit price by about 15.56%.
Unit-price change = ((new price ÷ new quantity) ÷ (old price ÷ old quantity) − 1) × 100%.
Supported inputs
Precision and limits
Your scenario
No live price, promotion, retailer policy, tax, cultural norm, household consumption rate, attendance rate, or media speed is supplied automatically.
Plan, not a guarantee
Results organize visitor-entered assumptions. They do not guarantee availability, attendance, product life, savings, suitability, or contractual rights.
Precision and privacy
Inputs stay in this browser. Invalid denominators, contradictory counts, impossible percentages, and unsupported ranges return explicit messages rather than misleading results.
Calculator-specific boundary
Use the same quantity basis for both packages. Product reformulation, quality, taxes, promotions, and package contents are not assessed.
Continue calculating