Unit Economics 101: The Metrics VCs Actually Care About

You’re in a partner meeting at a top-tier VC fund. The pitch is going well. Then someone asks: “Walk me through your unit economics.” If your answer starts with “well, it depends…” you’ve already lost the room.

Unit economics are the foundation of every investment decision. They answer one question: does your business model actually work at the individual customer or transaction level?

The Core Metrics

Customer Acquisition Cost (CAC)

Total sales and marketing spend divided by new customers acquired in the same period. Common mistakes: excluding sales salaries, mixing in brand spend, or using the wrong time attribution window.

What good looks like: VCs want to see CAC trending down as you scale or at least stable.

Lifetime Value (LTV)

Average revenue per customer × gross margin × average customer lifespan. For subscription businesses: (ARPU × Gross Margin) / Monthly Churn Rate.

What good looks like: LTV should be calculated on a gross margin basis, not revenue.

LTV:CAC Ratio

The single most scrutinized metric in any fundraise. For every dollar you spend acquiring a customer, how many dollars of gross profit do you get back?

What good looks like: 3:1 or higher is the benchmark. Below 3:1, you’re spending too much. Above 5:1, you’re likely under-investing in growth. Sweet spot: 3:1 to 5:1.

CAC Payback Period

How many months until a customer generates enough gross profit to cover their acquisition cost. CAC ÷ (Monthly ARPU × Gross Margin).

What good looks like: Under 12 months for SaaS, under 6 months for e-commerce.

Contribution Margin

Revenue minus all variable costs directly associated with serving that customer: COGS, fulfillment, payment processing, customer support allocation, and variable commissions.

What good looks like: 60%+ for SaaS, 30-50% for e-commerce, 40-60% for services.

How to Present Unit Economics

Show the trend, not just the snapshot. Present 6-8 quarters of data. VCs care more about direction than absolute numbers.

Segment when it matters. If you have multiple products or channels with meaningfully different economics, show them separately. Blended averages hide problems.

Connect to cash flow. Unit economics should flow directly into your financial model. Show how improving CAC payback by 2 months changes your cash needs by $X.

Be honest about what’s not working. Every company has a segment with weak unit economics. Name it, explain why, and share your plan.

Do This Monday

1. Calculate your blended CAC and LTV:CAC ratio. If you can’t do it in 30 minutes, your financial infrastructure needs work.
2. Pull your CAC by channel. Identify which channels have the best and worst payback periods.
3. Ask your finance team for contribution margin by customer segment. If they can’t produce it, that’s a sign you need stronger FP&A capabilities.

If you want help building investor-ready unit economics, book a free consultation →