Is $80,000 MRR efficient growth?
Revenue is not gross profit. Count model usage, human delivery and customer retention before you call AI growth efficient.
The question
At the seed stage, MorrowDesk has 20 paying customers and $80,000 MRR. Its AI draft says “software margins and rapid CAC payback.” Use this month’s actual delivery costs to test that claim.
| Amount | |
|---|---|
| Revenue | 80000 |
| Model inference | 25000 |
| Human service delivery | 15000 |
| Hosting | 3000 |
| Sales and marketing spend | 60000 |
| New paying customers | 5 |
Invented US dollars. Human service delivery is required to fulfil the customer service. Sales and marketing is acquisition cost, not cost of revenue. Use average revenue and cost per customer; ignore timing and cohort differences only for this first-pass calculation.
“Rebuild gross margin and CAC payback. What evidence is still missing?”
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A strong answer, step by step
Open each step in turn. This is one strong answer, not the only one.
Step 1: Count all delivery costs
What would you do here? Open the move you’d make.
Exclude people because the product is sold as software.
Tempting, but it misses something. The customer still requires that work. Excluding it would inflate gross margin.
Include inference, required human delivery and hosting.
The strong move. These costs support the delivered service, regardless of the marketing label.
Put the whole sales budget in cost of revenue.
Tempting, but it misses something. That spend acquires customers. Keep it in CAC to avoid mixing delivery with acquisition.
See how a strong candidate says it
“Cost of revenue is $43,000: $25,000 inference, $15,000 human delivery and $3,000 hosting. Gross profit is $37,000.”
Why it works: Required human delivery is part of fulfilling the service.
Step 2: Calculate the margin
What would you do here? Open the move you’d make.
Use 68.75% after inference only.
Tempting, but it misses something. That excludes $18,000 of necessary delivery costs.
Use 46.25% after all $43,000 of delivery cost.
The strong move. The company retains $37,000 before acquisition and other operating expenses.
Use revenue growth instead of margin.
Tempting, but it misses something. Growth does not measure how much revenue remains after service delivery.
See how a strong candidate says it
“Gross margin is $37,000 divided by $80,000, or 46.25%.”
Why it works: The arithmetic makes the claim testable.
Step 3: Match acquisition cost to gross profit
What would you do here? Open the move you’d make.
Divide CAC by $4,000 revenue: three months.
Tempting, but it misses something. Revenue-based payback omits ongoing delivery cost.
Use $12,000 divided by $1,850: about 6.5 months.
The strong move. This uses gross profit. It remains a first-pass average, not a cohort forecast.
State lifetime value from this month’s margin.
Tempting, but it misses something. Lifetime value requires a retention assumption that this data does not provide.
See how a strong candidate says it
“CAC is $60,000 divided by five, or $12,000. Monthly gross profit per average customer is $1,850. Payback is about 6.5 months.”
Why it works: Revenue-based payback would ignore the cost of serving the customer.
Step 4: Test what the average hides
What would you do here? Open the move you’d make.
Accept the average as proof every customer is profitable.
Tempting, but it misses something. Different usage and support needs can produce different margins.
Ask for a prettier AI forecast.
Tempting, but it misses something. A forecast can restate assumptions without supplying customer evidence.
Inspect customer cohorts and the cost of high-usage accounts.
The strong move. This tests durability and the main reason the margin may change.
See how a strong candidate says it
“I need cohort retention, usage cost by customer and evidence that new accounts need less human work. The average may hide loss-making heavy users.”
Why it works: Unit economics improve only if the mechanism survives scale and retention.
The answer, in short
- Decision
- The first-pass payback is about 6.5 months; the software-margin claim is unsupported.
- Because
- Fully loaded gross margin is 46.25%, and no retention history establishes lifetime value.
- What would change it
- Retained cohorts with lower human work and positive margin even at high usage.
Common traps
- Using revenue rather than gross profit for payback.
- Removing required people from cost of revenue.
Check your answer
- Did I include all service delivery costs?
- Did I calculate 46.25%?
- Did I calculate $12,000 CAC and 6.5-month payback?
- Did I name the cohort evidence still needed?
Last reviewed Nov 10, 2026