Free calculator
Percentage growth calculator for MoM, YoY and CAGR
Find the growth between two numbers and the compound rate behind it, project growth forward, see how long it takes to double or to reach a revenue target, and check a viral loop’s k-factor.
Your numbers
Period
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Total growth
+150.0%
From 10,000 to 25,000 over 12 months: 7.93% a month, compounded.
- Per month, compounded
- 7.93%
- Simple average per month
- 12.5%
- Week over week
- 1.78%
- Quarter over quarter
- 25.7%
- Year over year (CAGR)
- 150.0%
- Doubling time
- 9.1 months
Compounding path against a straight line
Quick answer
How do you calculate percentage growth?
Percentage growth = (new value − old value) ÷ old value × 100. Growing from 10,000 to 25,000 is 150%. Spread over several periods, use the compound rate: (end ÷ start)^(1 ÷ periods) − 1. Over 12 months that is 2.5^(1/12) − 1 = 7.9% a month, not 150 ÷ 12 = 12.5%. Measured in years, the same formula gives CAGR.
How to use the growth rate calculator
- Pick a mode
Two values for growth between two numbers, Projection to compound forward, Doubling for doubling time, Target for months to an MRR goal, K-factor for a viral loop.
- Enter the numbers and the period
Pick the unit your numbers are measured in: day, week, month, quarter or year. Rates can be negative in Projection.
- Read the result
See total growth, the compound rate and its weekly, monthly and yearly equivalents, plus a chart of the path.
- Share it
Copy the link to send the exact numbers. Nothing is stored on our side.
How the calculator works
Percentage growth compares two values: the change divided by where you started. When the change happened over several periods, the calculator also finds the steady rate per period that turns the start into the end, because each period grows on top of the last one.
Rates convert between units by compounding on periods per year: 52 weeks, 12 months, 4 quarters. A monthly rate r is (1 + r)¹² − 1 a year; over years, that yearly rate is the CAGR. Doubling time is ln 2 ÷ ln(1 + r), and the rule of 72 approximates it as 72 ÷ the rate in percent.
Months to a target is ln(target ÷ today) ÷ ln(1 + monthly growth), rounded up. The viral mode uses the simple loop described by David Skok: each new user sends invites once, so each cycle adds the previous cycle’s new users × k, where k = invites × sign-up rate.
Percentage growth = (end − start) ÷ start
Compound rate per period = (end ÷ start)^(1 ÷ periods) − 1
CAGR = (end ÷ start)^(1 ÷ years) − 1
Projection = start × (1 + rate)^periods
Doubling time = ln 2 ÷ ln(1 + rate) ≈ 72 ÷ rate in %
Months to target = ln(target ÷ current) ÷ ln(1 + monthly growth)
Viral coefficient k = invites per user × sign-up rateWorked example
- MRR grew from $10,000 to $25,000 in 12 months.
- Total growth: ($25,000 − $10,000) ÷ $10,000 = 150%.
- Monthly rate: 2.5^(1/12) − 1 = 7.93% a month, compounded.
- Weekly equivalent: 1.0793^(12/52) − 1 = 1.78% week over week.
- Doubling time at 7.93%: ln 2 ÷ ln 1.0793 = 9.1 months; the rule of 72 gives 72 ÷ 7.93 = 9.1.
Growth benchmarks for startups and SaaS
Published growth rates to compare yours with, each with its source.
| Benchmark | Growth rate | Source |
|---|---|---|
| Good growth during Y Combinator | 5% to 7% a week | Paul Graham (2012) |
| Exceptional growth during Y Combinator | 10% a week | Paul Graham (2012) |
| “Haven’t yet figured out what you’re doing” | 1% a week | Paul Graham (2012) |
| T2D3, once ARR reaches $2M | 3x, 3x, then 2x, 2x, 2x a year | Neeraj Agrawal, Battery Ventures (2015) |
| Median private B2B SaaS company, 2025 | 22% a year | SaaS Capital (2026) |
| Bootstrapped / equity-backed, 2025 | 20% / 25% a year | SaaS Capital (2026) |
Paul Graham’s rates are for startups during Y Combinator; T2D3 describes fast-growing venture-backed SaaS; SaaS Capital surveyed more than 1,000 private B2B SaaS companies. Last verified October 27, 2026.
Compound growth vs simple average growth
Dividing total growth by the number of periods gives a simple average that ignores compounding: 150% over 12 months is not 12.5% a month. Each month grows on top of the one before, so the steady monthly rate is 7.9%. Quote the compound rate when you compare months, plan a target or report CAGR to investors.
Rule of 72 vs the exact doubling time
The rule of 72 divides 72 by the growth rate in percent. It is closest around 8% per period and drifts further off as rates climb, which matters for startup growth rates measured per month or per week.
| Growth per period | Exact doubling time | Rule of 72 | Rule of 72 error |
|---|---|---|---|
| 1% | 69.66 periods | 72.00 periods | +3.4% |
| 2% | 35.00 periods | 36.00 periods | +2.8% |
| 5% | 14.21 periods | 14.40 periods | +1.4% |
| 8% | 9.01 periods | 9.00 periods | -0.1% |
| 10% | 7.27 periods | 7.20 periods | -1.0% |
| 20% | 3.80 periods | 3.60 periods | -5.3% |
| 50% | 1.71 periods | 1.44 periods | -15.8% |
| 100% | 1.00 periods | 0.72 periods | -28.0% |
What a viral coefficient means
The viral coefficient k is invites per user times the share of invites that sign up. David Skok’s rule: k must be above 1 for viral growth. Below 1 a loop still adds users, but the total levels off at starting users ÷ (1 − k). Skok also stresses cycle time, how long one loop takes, which he ranks above k: halving it doubles how fast the same k compounds.
Growth rate questions
- How do you calculate percentage growth?
- Subtract the old value from the new one, divide by the old value and multiply by 100. From 80 to 100 is (100 − 80) ÷ 80 = 25% growth. From 100 to 80 is a 20% decline.
- How do you calculate YoY growth?
- (This year − last year) ÷ last year × 100. Revenue of $1.2M against $900k a year earlier is 33.3% year-over-year growth. Compare the same month or quarter across years to remove seasonality.
- How do you calculate CAGR?
- CAGR = (ending value ÷ starting value)^(1 ÷ years) − 1. $1M growing to $4M in 3 years is 4^(1/3) − 1 = 58.7% a year.
- How do you calculate month-over-month growth?
- (This month − last month) ÷ last month × 100. For the average over several months, use the compound rate: (last month ÷ first month)^(1 ÷ months between them) − 1.
- What is the rule of 72?
- A shortcut for doubling time: 72 divided by the growth rate in percent. At 8% a year a value doubles in about 9 years. It is most accurate near 8%; at 50% a period it says 1.44 periods against an exact 1.71.
- What is a good monthly growth rate for a startup?
- Paul Graham’s essay “Startup = Growth” calls 5–7% a week a good rate during Y Combinator and 10% a week exceptional. SaaS Capital found the median private B2B SaaS company grew 22% in 2025, about 1.7% a month.
- What is a k-factor?
- The viral coefficient: how many new users each user brings in. k = invites sent per user × the share of invites that sign up. 5 invites at 10% is k = 0.5. Above 1, each cycle of new users is larger than the last.
- How long until I reach my MRR target?
- Months = ln(target ÷ current MRR) ÷ ln(1 + monthly growth), rounded up. From $10k to $100k MRR at 8% a month: ln 10 ÷ ln 1.08 = 29.9, so 30 months.
- Is my data stored?
- No. The calculator runs in your browser and sends nothing to SaaSCity. The share link puts your numbers in the URL, so only people you send it to see them.
Cite this tool
Free to link and quote. Use this reference:
SaaSCity, "Percentage Growth Calculator", October 27, 2026. https://saascity.io/free-tools/growth-rate-calculator