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Year Over Year Percentage Calculator

Find year over year percent change for sales, cost, orders, traffic, or any metric with a prior and current value.

By The Calcumatix Team Reviewed by Calcumatix Editorial Review

Result

+15%

From $100,000.00 to $115,000.00 is a 15% year-over-year increase

Quick Answer

Year-over-year percentage is the current value minus the prior value, divided by the prior value, times 100, so a rise from 84,000 to 97,500 is ((97,500 - 84,000) / 84,000) x 100, which is 16.07 percent. The prior value is the base. This calculator compares any two periods a year apart, and a negative result means a decline.

Understanding The YoY Percentage Calculator

A year over year percentage calculator shows how much a metric changed from one period to the matching period in the prior year. Enter the prior value and the current value. The calculator subtracts the prior value from the current value, divides by the prior value, then turns the answer into a percent. Business owners and analysts use YoY change for sales, cost, orders, traffic, stock, and other records. A matching month or quarter can give a cleaner view than a month-to-month check when the business has a strong season. A positive result means growth. A negative result means decline. The calculator gives the rate, but your notes explain why the change happened.

The Math Behind The YoY Percentage Calculator

Current value is the newer period. Prior value is the matching older period. The prior value must be greater than zero. Use the same metric in both periods.

  • Year over year percentage = ((current value − prior value) ÷ prior value) × 100

Getting Started With The YoY Percentage Calculator

Inputs

  • Prior value: value from the earlier matching period.
  • Current value: value from the newer matching period.

Steps

  1. Enter the prior value.
  2. Enter the current value.
  3. Check that both values measure the same thing.
  4. Read the year over year percentage.
  5. Add notes on season, price, and one-time events.

YoY Percentage Calculator Example With Every Step Shown

Prior value = $84,000 and current value = $97,500.

  1. Year over year percentage = ((97,500 − 84,000) ÷ 84,000) × 100.
  2. 97,500 − 84,000 = 13,500.
  3. 13,500 ÷ 84,000 = 0.1607142857.
  4. 0.1607142857 × 100 = 16.07142857, rounded to two decimal places = 16.07%.

The year over year percentage change is 16.07%, rounded to two decimal places.

Where The YoY Percentage Calculator Is Most Useful

Use YoY change when you compare sales, cost, orders, rent, payroll, stock, or web traffic. Keep notes near the result. Price changes, one-time deals, and season shifts can all change the story behind the rate.

Putting A Year Over Year Change In Context

Start with the period. Compare the same month, quarter, or year. If the dates do not match, the YoY rate can mislead.

Keep a short note with the result. Mark price changes, one-time orders, new fees, or a late entry. Do not use one YoY rate as the whole story; check the dollar change too, since a small base can make a small dollar move look large. See the finance calculators hub for related tools.

Assumptions

  • Prior value is greater than zero.
  • Both values use the same metric.
  • Both periods match in timing.
  • The result rounds to two decimal places.
  • The calculator shows percent change, not only dollar change.

Limitations

  • The tool does not explain why a metric changed.
  • A small prior value can make the rate look large.
  • One-time events can skew the result.
  • The tool does not forecast future growth.

In Practice

The most common mistake is comparing periods that are not truly a year apart, or mixing partial-year figures, which distorts the trend. Use matching windows, such as full year against full year. Remember the prior value is always the base, so swapping the two numbers flips the sign and changes the size of the result.

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Frequently Asked Questions About YoY Percentage Change

How do you calculate year over year percentage?

Year over year percentage is current value minus prior value, divided by prior value, then multiplied by 100. Use matching periods for a fair comparison.

What does a negative YoY percentage mean?

A negative YoY percentage means the current value is lower than the prior value. The negative sign shows a decline.

Why compare year over year instead of month to month?

Year over year comparison can reduce season noise by matching like periods. Month to month checks can still help, but season shifts can blur the signal.

What happens if the prior value is zero?

A standard YoY percentage is not valid when prior value is zero. The formula divides by prior value, so zero has no valid base.

Is YoY percentage the same as CAGR?

YoY percentage is not the same as CAGR. YoY compares two matching periods, while CAGR smooths growth over several periods.

Sources

Reviewed for accuracy against the formula shown above.