Two vendors quote 99.9% uptime. One pays a 10% service credit when they miss it. The other pays nothing because their SLA carves out scheduled maintenance, third-party outages, force majeure, and anything they label "investigation pending". Headline uptime is the easy number to compare — the cost lives in the carve-outs. Here are the 15 SLA terms every comparison should pull out.
The uptime metric
1. Headline uptime percentage. 99.9% = 8.76 hours of downtime per year. 99.99% = 52.6 minutes. The difference is dramatic — make sure the number is comparable across vendors.
2. Measurement window. Monthly, quarterly or annual? Monthly windows are stricter for customers because a single bad day can breach the SLA. Annual windows let vendors smooth over bad weeks.
3. Outage definition. Does an "outage" require 100% unavailability, or counts degraded service? "Functional but ≥50% slower than baseline" should count.
Carve-outs that swallow the SLA
4. Scheduled maintenance. How much downtime is excluded? 4 hours/month is normal; 8+ hours starts to gut the SLA.
5. Emergency maintenance. Unbounded "we'll let you know" emergency maintenance windows are a red flag — push for a cap (e.g. 2 hours/quarter).
6. Third-party dependencies. If the vendor blames AWS for an outage, does the SLA pay out? It should — the customer doesn't care which sub-component failed.
7. Force majeure scope. Earthquakes, sure. "Cyberattacks of any nature" — push back, that's the vendor's job to defend against.
Response and resolution times
8. Priority tiering. How are P1/P2/P3 tickets defined? The vendor's definition of P1 might be much narrower than yours.
9. Time-to-first-response. The vendor's commitment to acknowledge a ticket. 15 minutes for P1 is good; 4 hours is poor for enterprise contracts.
10. Time-to-resolution. The vendor's commitment to actually fix the problem. Many SLAs don't include this; demand it.
11. Escalation path. Who do you call after the first level fails? Phone numbers in the contract, not just a portal.
Penalty mechanics
12. Service credit calculation. How is the credit calculated? % of monthly fees? % of the affected service tier? Round-down or round-up?
13. Credit claim process. Some vendors require the customer to file the claim within X days, with specific evidence. Miss the deadline, no credit.
14. Maximum credit cap. Most SLAs cap credits at 10-30% of the monthly fee. The remaining liability lives in the main contract liability cap.
15. Termination right. What level of repeated SLA breach gives the customer a termination right? Three breaches in 12 months is a fair starting point.
Comparing SLAs across vendors
A spreadsheet-based SLA comparison is brutal because every vendor structures their SLA exhibit differently. AI SLA comparison tools normalise the vocabulary — vendor A's "Service Credit Calculation" and vendor B's "Penalty Schedule" map to the same row. Free plan covers 4 comparisons per month, enough to validate the workflow with your most recent SLA negotiations.