Irish Calculators
Business

Year-over-Year Growth and Amount Change Calculator

Measure a year-over-year change between comparable amounts. Percentage growth requires a positive prior base; a multi-year compound annual rate is a different calculation.

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Your numbers

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How the calculation works

Compare a current amount with its previous-year counterpart using both absolute change and percentage growth. The tool preserves signed amounts but only gives a conventional growth percentage when the prior value is positive.

Absolute YoY change = current amount − prior-year amount. YoY growth = absolute change / prior-year amount × 100, reported when the prior base is positive.

  1. Match comparable periods

    Use the same duration, seasonal position and business perimeter. A year-to-date amount should be compared with the corresponding earlier year-to-date period, not a complete prior year.

  2. Calculate the absolute movement

    Subtract the prior amount from the current amount. This remains useful even when the starting value is zero or negative and a conventional percentage is unavailable.

  3. Calculate growth from a positive base

    Divide the absolute change by the positive prior value and multiply by 100. Otherwise the tool leaves percentage growth undefined rather than presenting a misleading ratio.

Worked example: Growth

Sample inputs demonstrate the method. They are not a forecast or product offer.

The first example increases from €100,000 to €120,000. The absolute change is €20,000. Dividing that change by the €100,000 prior-year base gives growth of 20%.

Comparable prior-year amount
100000
Current-year amount
120000

Expected result

Absolute year-over-year change
€20,000.00
Year-over-year growth
20%
Worked example: Decline

Sample inputs demonstrate the method. They are not a forecast or product offer.

Comparable prior-year amount
200
Current-year amount
150

Expected result

Absolute year-over-year change
-€50.00
Year-over-year growth
-25%

Understanding your result

Absolute movement and percentage growth answer different questions. The first gives the size of the change in the original units; the second relates it to the earlier positive scale.

The result is not automatically adjusted for inflation, acquisitions, exchange rates or accounting changes. It also does not annualise a multi-year change into CAGR.

Questions you might have

What happens when the prior year was a loss?

The absolute improvement or deterioration is shown. A conventional percentage with a negative denominator can mislead, so this tool does not label it as growth.

Choosing the right inputs

Comparable prior-year amount
Enter the earlier period's amount on the same measurement basis as the current value. A zero or negative base does not support the usual percentage-growth interpretation here.
Current-year amount
Enter the comparable current amount, including a negative value where appropriate. Do not convert a loss to positive merely to make the percentage look more familiar.

Common mistakes to avoid

  • Do not divide by the current amount when calculating growth relative to the prior year.
  • Do not interpret an unavailable percentage from a zero base as zero growth; the absolute change may still be substantial.

Assumptions to check

  • Use amounts in one currency and one reporting period. Results are labelled EUR; the arithmetic also works for another consistent currency.
  • This is a one-period comparison, not a compound annual growth rate across several years.

Sources and method

Read our calculation and testing approach.