Interactive Calculator

SaaS Return on Capital Flywheel

See how capital flows through a SaaS firm and compounds sticky recurring revenue. Toggle Golden Section Lending to see what non-dilutive debt does to the math.

Your Inputs

Capital Invested $1,000,000
Initial S&M investment deployed into proven channels.
Sales Cycle 6 months
Average time from S&M spend to closed ARR.
Sales Efficiency Ratio 0.80×
S&M cost to create $1 of new ARR. Lower is better — 0.5× means $1 creates $2 of ARR.
Golden Section Lending Borrow 40% against ARR — reinvest 90% of total ARR instead of 50%.
Cumulative ARR Over 5 Years
Period-by-Period Breakdown
Period S&M Deployed New ARR Cumulative ARR

What the SaaS Capital Flywheel is.

The SaaS Capital Flywheel is Golden Section’s model for how capital compounds inside a healthy software company. Each dollar of sales and marketing spend creates new recurring revenue; a portion of that revenue is reinvested into the channels that produced it; and the cycle repeats, with each turn starting from a larger base. Non-dilutive debt accelerates the flywheel by increasing how much of each turn’s revenue can be reinvested — without selling equity to do it.

The four stages

1. Deploy into proven channels. Capital goes into sales and marketing motions with demonstrated payback — not experiments. The discipline is the point: the flywheel only compounds if each dollar reliably creates new annual recurring revenue.

2. ARR expands. New customers land, recurring revenue grows, and the company’s enterprise value and borrowing capacity grow with it. Revenue growth improves the terms available on future credit facilities.

3. Equity is retained. Because growth was funded from operating cash flow and debt rather than new equity rounds, founders and existing shareholders own the same share of a larger business. The compounding accrues to them.

4. Refinance at better terms. Higher ARR and stronger unit economics unlock larger facilities at lower cost. Cheaper capital feeds stage one, and the flywheel turns faster.

The underlying math

New ARR = S&M deployed ÷ Sales Efficiency Ratio.
The Sales Efficiency Ratio (SER) is the sales and marketing cost of creating $1 of new ARR — an SER of 0.80× means $1.00 of spend creates $1.25 of ARR. Each period, the model reinvests 50% of total cumulative ARR into the next period’s sales and marketing. Toggling Golden Section Lending raises the reinvestment rate to 90%, representing borrowing of roughly 40% against ARR. Reinvestment cycles run at 1.2× the initial sales cycle length.

A worked example

Take the calculator’s default inputs: $1,000,000 deployed, a 6-month sales cycle, and an SER of 0.80×. The first three turns of the flywheel look like this:

PeriodMonthS&M deployedNew ARRCumulative ARR
16$1.00M$1.25M$1.25M
213$0.63M$0.78M$2.03M
320$1.02M$1.27M$3.30M

By month 20, $1M of initial capital has produced $3.30M of cumulative ARR. Run the same three periods with lending switched on — reinvesting 90% of cumulative ARR instead of 50% — and cumulative ARR reaches $5.64M by month 20, with founders holding the same equity in both scenarios. That difference is the whole argument for non-dilutive capital: the spread compounds every period, and none of it was paid for with ownership.

The model is deliberately simplified — it holds SER constant and ignores churn, so long horizons overstate what any real company achieves. Its purpose is to make one mechanism visible: reinvestment rate is the lever that non-dilutive capital moves, and small changes to it compound into large differences in outcome. The full assumptions are stated above and in the calculator’s inputs.

Read more about how this pairs with our credit products on the Lending page, or see the equity side on Ventures.