π Year-over-Year Growth Calculator
True growth, seasonality removed.
YoY growth
Estimates for planning only, not financial advice.
$1,200,000 this year against $1,000,000 in the same period last year is +20.0 percent year-over-year, a $200,000 absolute gain, 1.20x last year's figure. Because both periods cover the same season, the growth is real signal, not calendar noise.
How to Use This Calculator
Enter the current period's value and the same period last year's value: same quarter, same month, same week. The calculator returns the growth rate, absolute change, and multiple.
Match periods exactly: Q3 vs Q3, March vs March. Mismatched periods reintroduce seasonality.
Read the percent for the headline and the absolute for the business weight.
Check the base: huge percents on tiny bases are arithmetic, not achievement.
The Formula
The power is in the comparison design: same-period-last-year automatically controls for seasonality, holidays, and annual cycles. That is why earnings reports lead with YoY: it is the closest thing to a clean growth signal in periodic data.
Worked Example
Current 1,200,000, prior 1,000,000. Change: (1,200,000 - 1,000,000) / 1,000,000 = +20.0 percent. Absolute: +$200,000. Multiple: 1.20x. Two-year view: if the year before was also 1,000,000... the calculator's CAGR-pace line shows the annualized rate over two years: with 1,440,000 vs 1,000,000 two years apart, sqrt(1.44) - 1 = 20.0 percent annualized. Stack YoY quarters to see acceleration or deceleration: 25%, 20%, 15% is a slowdown wearing growth's clothes.
Base Effects
| Situation | YoY says | Reality |
|---|---|---|
| Prior year had a crash | +80% | Recovery, not boom |
| Prior year had a one-off spike | -20% | Normalization, not collapse |
| Steady compounding | +20% | Genuine growth |
Always ask what the base contained. Lapping a terrible quarter flatters; lapping a great one punishes. Two-year stacked growth ((current / two-years-ago) - 1) cuts through base effects and is the analyst's standard antidote.
YoY in Context
Pair YoY with sequential (quarter-over-quarter or week-over-week) momentum: YoY tells you the trend, sequential tells you the turn. A company growing 20% YoY but shrinking 5% sequentially is decelerating into the number. For the multi-year compounding behind the growth, our time value of money calculator shows how sustained rates build.
YoY vs CAGR: Picking the Right Growth Metric
Year-over-year growth tells you what happened in one year; CAGR (compound annual growth rate) tells you the smooth annualized rate across many. A company growing revenue 100 percent, then 0 percent, then 100 percent has wild YoY figures but a two-year CAGR of about 41 percent: the CAGR describes the full trajectory, the YoY figures describe the weather. Use YoY for diagnosing recent performance and spotting turning points; use CAGR for valuing, comparing multi-year track records, and setting targets.
The two can disagree sharply, and the disagreement is informative. Accelerating YoY above the historical CAGR means growth is speeding up; decelerating YoY below it means the trend is fading even if the headline still looks positive. Investors pay for the direction of the change: stocks often peak when YoY growth is highest but decelerating, because expectations priced the acceleration continuing. Report both, and always say which one your conclusion rests on.
Annualize carefully with partial years. Comparing year-to-date this year against full-year last year is the classic error; compare YTD against the same YTD period last year, or annualize with explicit seasonality adjustments. For quarterly earnings, the standard is quarter-over-same-quarter-last-year (a YoY on quarters), which is why "Q3 revenue up 12% YoY" means versus Q3 last year, not versus Q2. Match the periods or the percentage is fiction.
Growth, Honestly Measured
Year-over-year growth is the standard yardstick for business performance: simple, seasonal-proof, and comparable. Use it for recent trends and turning points, CAGR for multi-year stories, and always check base effects before celebrating or panicking. A percentage without its base year is just a rumor with math.
Growth Numbers That Inform
Report YoY with its context always attached: the base year, the absolute change, and the multi-year CAGR. "Revenue grew 25% YoY to $10M, a 3-year CAGR of 18%" tells a complete story; "revenue grew 25%" tells a rumor. Analysts, investors, and managers all make better decisions from the fuller sentence, and it takes five extra words.
Use YoY for spotting turns, CAGR for valuing trajectories, and absolute dollars for sizing what the percentages mean. A 50 percent grower adding $1M and a 10 percent grower adding $10M are different businesses; the percentage never says which. Growth is a vector: direction, magnitude, and base all matter.
Beware the percentage-point trap in reporting: growing from 10% to 15% growth is a 5-percentage-point acceleration but a 50 percent increase in the growth rate. Both phrasings are correct and they imply very different things. State which one you mean, or your audience will pick the flattering one.
For personal finance, YoY works too: compare this year's savings, net worth, or spending against last year's to see real progress stripped of monthly noise. The same discipline that judges companies judges households. Measure yearly, act monthly.
Estimates for planning only, not financial advice.
Frequently Asked Questions
How do you calculate year-over-year growth?
(Current period - same period last year) / same period last year x 100. $1.2M vs $1.0M = +20%. Match periods exactly (Q3 vs Q3) to keep seasonality out. Comparing Q4 against Q3 instead would mix real growth with holiday seasonality; the whole point of YoY is comparing like with like.
What is YoY growth?
The percentage change versus the same period one year earlier. It is the standard growth metric in earnings reports because comparing identical seasons removes calendar and seasonal distortion. Every earnings headline you read ('revenue up 12% YoY') uses this definition; it is the lingua franca of business performance.
YoY vs MoM: which is better?
YoY for true trend (seasonality-free), MoM/sequential for detecting turns early. Use both: YoY can hide a recent slowdown, sequential can overreact to noise. Together they show direction and momentum. A company with strong YoY but three weak sequential quarters is decelerating into a good headline; the sequential data is the early warning.
What is a good YoY growth rate?
Mature companies: 5-15% is healthy. High-growth startups: 50-100%+ is expected early, decaying as the base grows. Always judge against the industry and the base size, not absolute percentages. A utility growing 8% is a star; a SaaS startup growing 8% is in trouble: the same number means opposite things in different contexts.
What are base effects?
Distortions from unusual prior-year periods: lapping a crash inflates YoY, lapping a spike depresses it. Two-year stacked growth (current vs two years ago) neutralizes base effects. Retailers' 2021 YoY figures looked heroic only because 2020 was catastrophic; the two-year stack told the honest story of modest cumulative growth.
Can YoY be negative?
Yes: -10% means the metric shrank a tenth versus last year. Negative YoY revenue with positive YoY profit can signal successful restructuring; negative on both is contraction. Read the pair. Turnaround investors specifically hunt negative-revenue, positive-profit inflections: they mark the moment cost discipline starts working before growth returns.
How do you calculate 2-year stacked growth?
(Current / value two years ago - 1) x 100. It shows total growth across the base-effect window. Annualize with the square root for a CAGR-equivalent pace. A 44% two-year stack annualizes to 20% CAGR (sqrt(1.44) - 1); reporting the annualized figure lets you compare it directly against single-year YoY numbers.
Why do companies report YoY instead of sequential?
Because YoY is comparable across seasons and harder to manipulate with timing shifts. Sequential (QoQ) is more current but noisier; most reports show both with YoY as the headline. Pulling a shipment forward a week boosts one quarter and robs the next; YoY comparisons wash out that gamesmanship, which is partly why auditors and analysts prefer them.
Does YoY work for weekly data?
Yes: this week vs the same week last year is an excellent high-frequency trend metric, keeping weekly speed while removing seasonality. Retail and web analytics use it heavily. Watch out for holiday-week misalignment (Thanksgiving shifts weeks between years); align on the holiday, not the calendar week, for honest retail comparisons.
What if last year's value was zero?
Percentage change is undefined (division by zero). Report the absolute change and note the base was zero; 'infinite growth' from nothing is arithmetic trivia, not insight. Startups going from $0 to $100K revenue have undefined YoY growth but very real progress; quote the dollars and save percentages for year two.