How Much Does a SIEM Cost? Licensing vs. Custom-Built

Licensed vs. Custom-Built SIEM at a Glance#

What Drives SIEM Licensing Costs?#

To begin with, licensed SIEM pricing is based on four measurable inputs. Let's walk through each one in turn.

Ingestion volume

For example, Splunk, Microsoft Sentinel, and IBM QRadar are all priced based on data volume. Specifically, rates range from €1 to €4 per GB per day. As a result, at 100 GB per day or more, this line item accounts for the majority of total spend.

Retention periods

Similarly, standard licensed plans include 30 to 90 days of hot storage. However, NIS2 and DORA mandate longer log retention windows, as our NIS2 and DORA compliance guide explains. Because of this, extended retention activates additional storage tiers, and in turn, each tier raises the annual cost.

Feature tiers

In addition, core detection, SOAR integration, behavioral analytics, and threat intelligence feeds are available only on higher-cost plans. Consequently, teams on entry-level licenses hit a ceiling fast. Therefore, they upgrade when advanced correlation or automated response becomes necessary. For more detail, our SOAR playbooks guide covers what response automation involves at each tier.

Tenant count

Finally, per-tenant licensing sharply increases costs for MSSPs and enterprises with multiple business units. Unfortunately, most licensed platforms were not built for true multi-tenancy. As a result, each new tenant requires a separate instance, a separate license, and separate overhead. To see how this plays out in practice, our multi-tenant SIEM architecture guide breaks it down.

What Hidden SIEM Costs Do Teams Overlook?#

Beyond the sticker price, published pricing rarely reflects total cost of ownership. In fact, security teams hit four hidden costs that never appear in a vendor proposal.

Tuning and maintenance. To start with, out-of-the-box rules generate substantial false positives. As a result, analysts adjust thresholds, refine detection logic, and update parsers on an ongoing basis. Unfortunately, most teams underestimate this time during procurement.

Professional services. Additionally, initial setup, data source integration, and legacy migration require vendor consultants or third parties. Consequently, engagements range from tens of thousands to six figures, depending on environmental complexity.

Storage overruns. Moreover, security incidents, audits, and new data sources push ingestion above contracted tiers. When that happens, vendors bill overages at rates well above the base per-GB cost.

Data egress. On top of that, cloud-hosted SIEMs charge for data egress from the platform. Therefore, teams exporting logs for analysis, archiving, or compliance accumulate egress fees year-round.

Taken together, these four categories add an estimated 30-50 percent to the base licensing fees. That said, actual figures vary by environment and vendor.

Licensed SIEM vs. Custom-Built: Which Model Costs Less?#

Ultimately, the answer depends on data volume and time horizon. To make the comparison clear, let's look at each model in turn.

How licensed SIEMs work financially

To begin with, costs start on day one. On the surface, the structure is predictable; however, the actual bill is not. In practice, a growing environment produces a growing bill. On the plus side, licensed platforms deploy in weeks with no upfront engineering investment.

How custom-built SIEMs work financially

In contrast, a custom-built SIEM requires significant upfront engineering effort to design, build, and integrate. After that initial phase, however, ongoing costs cover infrastructure only. In other words, compute, storage, and maintenance replace per-GB licensing fees. For a fuller picture, our custom SIEM and SOAR development service outlines what this work involves.

Alternatively, open-source components offer a different path to cost control. That said, this route carries its own trade-offs, all of which are covered in our open-source vs. custom-built SIEM guide.

Where the break-even point falls

Generally speaking, for most high-volume environments, the custom-built total cost drops below licensed spend within 18 to 36 months. However, organizations under 50 GB per day rarely reach that crossover fast enough to justify the build. In contrast, those at 100 GB per day or more see a clear financial case within the window. Furthermore, MSSPs with multiple clients reach it fastest of all.

Who Benefits Most From a Custom-Built SIEM?#

As a general rule, custom-built SIEMs deliver the strongest return in four specific scenarios. Let's consider each one.

MSSPs managing multiple tenants. First and foremost, licensing costs multiply with each client on most commercial platforms. By comparison, a custom architecture with native multi-tenancy removes per-tenant licensing and, in turn, shares infrastructure across clients. To understand how this works, our MSSP engineering partner services overview explains it in detail.

High-volume enterprise environments. Similarly, organizations ingesting hundreds of gigabytes daily face compounding per-GB costs. Because of this, a fixed-cost infrastructure model grows more favorable at this scale.

Regulated industries with strict data control. In addition, sectors under NIS2, DORA, HIPAA, or similar frameworks need granular control over data residency, retention architecture, and audit trails. Unfortunately, commercial platforms often cannot fully deliver that.

Teams with existing engineering capacity. Finally, the model works best when the organization owns ongoing development and maintenance. Otherwise, without that capacity, operational costs erode the financial advantage.

What Real-World Cost Reduction Can You Expect?#

To be clear, exact figures depend on current spend, data volumes, and environment complexity. As a result, any vendor quoting specific percentages without an architecture review is simply not working from your numbers.

Nevertheless, organizations migrating from high-volume licensed deployments to custom architectures consistently report meaningful reductions in annual security operations spend. In most cases, savings appear once the platform reaches steady state. Above all, eliminating per-GB ingestion fees and per-tenant licensing overhead drives the biggest gains.

Of course, migration carries real risk. For that reason, our zero-downtime migration guide walks through how to move without a coverage gap.

Which SIEM Model Fits Your Situation?#

To simplify the decision, use the quick reference below.

The Bottom Line#

On the one hand, licensed SIEMs offer speed and a lower upfront cost. Therefore, for teams early in their security journey or running modest data volumes, that is a real advantage. On the other hand, the per-GB model creates a structural problem; specifically, a growing environment generates a growing bill, often outpacing improvements in security posture.

By contrast, custom-built SIEMs require patience and upfront engineering investment. Even so, for MSSPs, high-volume enterprises, and regulated operators, the investment pays off within two to three years. Moreover, the cost curve flattens sharply after that point.

In the end, which model costs less depends on where you stand today and where you are headed. Consequently, a clear look at current spend, growth trajectory, and internal capacity gives you the answer.

Frequently Asked Questions#