Prometheus vs VictoriaMetrics — Which One Should You Use? (2026)

Prometheus is the default monitoring choice in Kubernetes. But teams running at scale — millions of time series, multi-cluster setups — are switching to VictoriaMetrics. Here's what you need to know.

Quick Summary

When Prometheus is the Right Choice

Use Prometheus if:

• You're starting fresh and cluster is small-medium (< 1M active time series)
• You need maximum ecosystem compatibility
• Your team already knows Prometheus well
• You want the most battle-tested setup with the largest community

Prometheus + Grafana + AlertManager is still the most common monitoring stack in the world. For most teams, it's the right choice.

When VictoriaMetrics Wins

Switch to VictoriaMetrics if:

• You're hitting Prometheus memory limits (OOMKilled)
• You have millions of time series (high cardinality)
• You need multi-cluster metrics in one place
• You want long-term storage without Thanos complexity
• You want to cut infrastructure costs

At scale, VictoriaMetrics uses 5-10x less RAM than Prometheus for the same data. That's real money saved.

Storage Comparison

Prometheus uses its own TSDB format. VictoriaMetrics uses a more compressed format:

• Prometheus: ~3-5 bytes per sample (compressed)
• VictoriaMetrics: ~0.4-0.8 bytes per sample

For 1 billion samples per day, VictoriaMetrics stores this in 4-8 GB vs Prometheus's 30-50 GB.

High Availability

Prometheus HA:

• Run two identical Prometheus instances
• Use Thanos or Cortex for deduplication and long-term storage
• Complex setup, many moving parts

VictoriaMetrics Cluster:

vminsert (write) → vmstorage (store) → vmselect (read)

Built-in HA with replication factor. No Thanos needed.

Migration: Prometheus → VictoriaMetrics

VictoriaMetrics speaks Prometheus's scrape format natively. Migration is mostly changing the scrape target endpoint:

# Before (Prometheus scraping)
scrape_configs:
  - job_name: myapp
    static_configs:
      - targets: ['localhost:9090']
 
# After (vmagent scraping → VictoriaMetrics)
# Same config works — vmagent is a Prometheus-compatible scraper

Your existing Grafana dashboards work without changes. AlertManager works without changes.

MetricsQL vs PromQL

VictoriaMetrics uses MetricsQL, which is a superset of PromQL. All your existing PromQL queries work. MetricsQL adds extras:

# PromQL (works in both)
rate(http_requests_total[5m])
 
# MetricsQL extra — implicit conversion, smarter handling
increase(http_requests_total[5m])  # handles counter resets better

Resource Usage Example

For a 500-node Kubernetes cluster with typical workloads:

The Verdict

• Default choice: Prometheus. Battle-tested, massive ecosystem, works great for most teams.
• Scale choice: VictoriaMetrics. When Prometheus starts OOMKilling or Thanos becomes painful.
• Not an either/or: Many teams run Prometheus for short-term, VictoriaMetrics for long-term via remote_write.

Start with Prometheus. Migrate when you feel the pain.

Resources

• Prometheus + Grafana Setup Guide
• VictoriaMetrics Docs
• Course: Prometheus Monitoring on Udemy