Side Project · GTM Engineering

Product decisions
are revenue decisions.

A PLG activation funnel modeller. Drag the conversion rates at each onboarding step and watch how it flows through to paying users and ARR in real time.

PLG Revenue Modeling GTM Eng Side Project
📖 ~4 min read · Type: Side Project · Year: 2025

Live Demo

Move a slider. See the revenue impact.

Every percentage point in your onboarding funnel is worth real money. This makes that visible. Drag any conversion rate and watch how it flows through to paying users and monthly revenue.

Funnel inputs
Monthly visitors 20k
Sign-up rate 12%
Activation rate 35%
Retained at day 30 40%
Free-to-paid conversion 8%
Revenue inputs
Average plan price (MRR/user) $49
Expansion revenue rate 12%
Monthly churn rate 5%
Activation Funnel Overall conversion: 0%
New paying users/mo
New MRR
from this month's cohort
Net MRR (after churn)
ARR run rate
annualised from net MRR
Highest leverage move

Why I built this

Most teams fix the wrong thing.

When growth is flat, the default instinct is to push more traffic. Run more ads, post more content, buy more leads. But in a PLG motion, top-of-funnel is usually not the problem. A 10% improvement in traffic does almost nothing if your activation rate is broken.

The math is unintuitive until you see it visually. A 5-point lift in activation from 30% to 35% can outperform doubling your sign-up volume, depending on where the rest of the funnel sits. This tool makes that comparison instant.

The insight

"In a PLG funnel, the highest-leverage intervention is almost never where teams think it is. The model tells you where to look."

I built this because I kept having the same conversation - where should we focus? - and the answer always required doing the math first. Now the math does itself.


What the model tracks

Five stages, one number that matters.

01 · Sign-up
Visitor to free user
The first gate. Usually driven by landing page clarity and friction in the sign-up flow. Easy to A/B test, hard to move more than a few points.
02 · Activation
Free user to activated user
The most important step in PLG. Did the user hit the "aha moment"? This is where onboarding engineering has the most leverage - and where most teams under-invest.
03 · Day-30 retention
Activated user to retained user
Are they still here a month later? Retention is a product quality signal. If you can't retain activated users, converting them to paid is just delaying churn.
04 · Free to paid
Retained user to paying customer
Conversion from free to paid is about timing and value. Hitting users at the right moment with the right gate - usage limits, feature unlocks, seat caps - drives this number.

Learnings

What the model taught me.

Activation is almost always the highest-leverage stage. It's the step with the most room to improve and the biggest downstream multiplier. A 10-point activation improvement compounds through retention and conversion in a way that no other stage does.

Churn is silent until it isn't. Low churn looks fine month to month. Compound it over a year and it becomes the thing eating all your new MRR. The ARR run rate number in this model makes that visible fast.

Expansion revenue changes the math significantly. Teams that only think about acquisition miss that existing users growing their spend is often higher margin and more predictable than new logos. Flip the expansion slider and watch what happens to ARR.

Vanilla JS Revenue Modeling PLG Strategy GTM Engineering

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