You can drown in metrics. For a small acquisition, seven of them explain almost everything, and each answers a distinct question about whether you'll regret this.
1. MRR — is it real, and is it recurring?
The headline number, and the one most often overstated by including things that don't recur. Ask specifically: how much of this MRR renews without anybody doing anything?
2. Monthly churn — how fast does it leak?
Split voluntary from involuntary. Get it by cohort, not just as an average. See the other article on this — it's the metric that compounds.
3. Net revenue retention — does it grow without new customers?
Take last year's cohort, look at what they pay today. Above 100% means the existing base grows by itself. Below 85% means you must acquire continuously just to stand still.
4. CAC and payback period — what does growth cost?
If acquisition is entirely organic, CAC is near zero and the real question is whether the channel is durable. If it's paid, the number that matters is payback period: months of gross margin needed to recoup the acquisition cost. Under 12 months is workable for a small operator; over 18 means you're funding growth from savings.
5. Customer concentration — who can end this?
Top customer as a share of revenue, and top five combined. Over 10% for one customer is a risk you price. Over 25% is a risk you might decline.
6. Traffic concentration — who else can end this?
Same logic, applied to acquisition. One keyword, one referrer or one platform above half your inbound is a dependency on a decision you don't control.
7. Support load per customer — the one nobody checks
Tickets per hundred customers per month. This is the metric that determines whether the business is something you own or something that owns you. A tool with 400 customers and 15 tickets a month is passive income. The same revenue with 200 tickets a month is a support job with a software hobby attached.
Putting it together
Write the seven down for any business you're considering, before you look at the asking price. Then look. Most of the time the number will already feel obviously right or obviously wrong, and you'll be able to say precisely why — which is exactly the position you want to negotiate from.