Founder Financial Toolkit

Model the money before you build it.

Size the market, pressure-test the unit economics, and watch cash play out month by month. Change any input and every number updates live. It runs entirely in this browser — nothing is sent anywhere — and the starting figures each carry a basis, not a guess. Export the model as JSON to keep or share a snapshot.

Pricing & margin

Price / customer / month ($) Midpoint of a common $49–$99/mo entry tier — replaced by this idea's pricing anchor when seeded. Gross margin (%) SaaS gross margins run 70–85%; 80% is a defensible software default.

Acquisition & retention

CAC — cost to acquire one ($) Blended cost to win one customer with founder-led selling, before paid scale. Monthly churn (%) ~4%/mo logo churn (≈40%/yr) is a common early-stage figure; tighten it as retention proves out.

Customers & growth

Starting customers Pre-launch: the model starts from zero paying customers. New customers / month A realistic founder-led acquisition pace in the first year.

Costs & cash

Fixed monthly costs ($) Lean fixed monthly cost — tools, hosting, part-time help — before a team. Cash on hand ($) Starting cash a bootstrapped founder commits before revenue covers costs.

Market sizing

TAM — annual market ($) Top-down placeholder — replace with a bottom-up count of reachable buyers × annual price. SAM (% of TAM) The share of the market your channels can actually serve. SOM (% of SAM) The share of SAM you can realistically obtain in the first few years.

Horizon

Projection months (1–120) A 24-month horizon is long enough to see payback and churn play out.

— MRR (current) Starting customers × price. Month 1 of the table below.

— ARR (current) MRR × 12 at today's run-rate.

— Margin / customer / mo Price × gross margin — the cash each customer contributes.

— LTV per customer Margin × lifetime (1 ÷ churn), lifetime capped at 120 months.

— LTV : CAC Above 3.0 is the common health line.

— Payback (months) Months of margin to earn CAC back. None = margin ≤ 0.

— Break-even customers Customers whose margin covers fixed cost. None = margin ≤ 0.

— Runway (months) Until cash goes negative. None = cash-positive plan.

— SAM Serviceable slice of TAM your channels can reach.

— SOM Obtainable slice of SAM in the early years.

Projection

Customers, MRR, and cash by month.

Each row is the start of that month. Cash begins from cash-on-hand; net cash flow is margin minus fixed costs minus acquisition spend. Customers grow by net adds after churn.

Month	Customers	MRR	Net cash flow	Cash balance