Startup fundamentals
Compound growth
Why a small weekly rate beats a big absolute number, and how to convert weekly growth to monthly.
Compound growth means a quantity multiplies by a fixed factor each period, instead of adding a fixed amount. At 10% week-over-week, 100 users become about 14,000 in a year and about 2 million in two years. Early absolute numbers look tiny. The rate is what matters.
Venture-scale companies are designed around that rate. If you only watch the raw count, a company that is compounding and a company that is stalling can look the same for months.
The big idea
Think of a savings account. Adding $10 a week is linear. Earning 7% a week on the balance is compound. Startups are closer to the second picture: each week's new users or revenue become the base that next week's rate multiplies.
The analogy breaks when the rate is not stable. Real growth jerks around. You still convert the messy series into a rate so you can compare weeks, not just celebrate a one-off spike.
Walking through it
Early teams often aim for 5–7% growth per week on a primary metric (active users, revenue, or another leading indicator). At 7% weekly you roughly double every ten weeks.
Start at 200 weekly active users (WAU):
7% weekly for 52 weeks: 200 × (1.07)^52 ≈ 6,800 WAU
1% weekly for 52 weeks: 200 × (1.01)^52 ≈ 336 WAUSame starting point, same year of work. One looks like a rocket. The other looks like a side project. Investors and later employees are buying the first curve.
Later-stage companies quote monthly growth. Convert with:
monthly ≈ (1 + weekly)^4.33 − 1So 7% weekly is about 34% monthly — an extraordinary early rate that cannot last. Conversely, 10% month-over-month is about 2.2% weekly. When someone says "we're growing 10%," ask per what period.
Example
A seed pitch: "We grew 3× last year." From 40 to 120 customers in twelve months is about 8% month-over-month if the path was smooth. That can be solid B2B. It is weak if the same slide claims hypergrowth consumer dynamics. Convert to a rate, then compare it to the claim.
Common mistakes
- Reading the absolute number. 336 and 6,800 both started at 200. Without the rate you cannot tell them apart in month two.
- Mixing periods. "10% growth" with no week/month/year label hides underperformance.
- Treating a launch spike as a rate. One viral week is not 7% weekly compound.
- Assuming 7% weekly lasts forever. It is a search-phase compass, not a mature-company plan.
Check yourself
A company goes from 40 to 120 customers in a year and calls that hypergrowth. What do you compute first?
The implied monthly rate, about 8% month-over-month if growth was smooth.
Why can 7% weekly look boring in week three and enormous in week fifty-two?
Compounding multiplies the new base each week, so small rates explode only after many periods.
Key takeaways
- Compound growth multiplies by a rate each period. Absolute counts hide the trajectory.
- Mid-single-digit weekly growth is the usual early compass; 7% weekly is about 34% monthly.
- Always name the period. Ambiguous "10%" is how weak growth gets dressed up.
- Convert "we grew 3×" into a rate before you believe the adjective.
Further learning
Paul Graham's growth math, including the 10% weekly picture:
Startup = Growth (Paul Graham)Startup = Growthpaulgraham.comNext, see what that rate is for in what a startup is.