AzureAzure Cache for RedisDatabase

`azurerm_redis_cache` cost estimation

A managed Redis cache. Priced per hour by tier (Basic, Standard, Premium, Enterprise) and cache size.

An azurerm_redis_cache is a managed Redis instance. Pricing is dominated by the SKU tier and cache size.

Tier capabilities and pricing profiles:

Basic (sku_name = "Basic"): single-node, no SLA, cheapest. Right for dev/test. C0 (250 MB) is $0.022/hour; C6 (53 GB) is $1.105/hour.

Standard: two-node primary/replica with 99.9% SLA. Right for non-critical production. Same per-size price as Basic plus ~50% for the replica.

Premium: persistence, clustering, VNet integration, geo-replication. Significantly more expensive but supports advanced scenarios. P1 (6 GB) is $0.515/hour; P5 (250 GB cluster) is $20.62/hour.

Enterprise and Enterprise Flash: Redis Inc.'s OSS-licensed Enterprise tier with Active-Active geo-replication, Redis modules (RedisJSON, RediSearch, etc.), and tiered storage on Flash. Premium pricing, right for organizations standardizing on Redis Enterprise.

Per-hour rates apply continuously; cache that runs 24/7 pays 730 hours/month. There's no per-request or per-GB-stored fee beyond the per-hour rate.

Outbound data transfer to public internet incurs standard Azure egress charges. Intra-VNet access is free.

Reserved Capacity (1-year or 3-year commitments via the Azure portal, not Terraform) cuts prices by 30-55%.

c3x reads sku_name and family (C for Basic/Standard, P for Premium) from the resource. Cache size is from capacity (the index into the per-family size list).

Terraform example

A minimal but realistic configuration that C3X can estimate.

resource "azurerm_redis_cache" "main" {
  name                = "production-redis"
  location            = azurerm_resource_group.main.location
  resource_group_name = azurerm_resource_group.main.name
  capacity            = 1
  family              = "C"
  sku_name            = "Standard"
  minimum_tls_version = "1.2"

  redis_configuration {
    maxmemory_policy = "allkeys-lru"
  }
}

Pricing dimensions

What you actually pay for when you provision azurerm_redis_cache.

Dimension	Unit	What's being charged
Basic tier	per hour	Single-node cache, no SLA. Right for dev/test. $0.022/hour for C0 (250 MB) in eastus
Standard tier	per hour	Primary/replica with 99.9% SLA. ~50% more than Basic for the same size. $0.043/hour for C0 Standard
Premium tier	per hour	Persistence, clustering, VNet, geo-replication. Significantly higher per-GB. $0.515/hour for P1 (6 GB) in eastus
Enterprise/Enterprise Flash	per hour	Redis Enterprise tier with modules and Active-Active geo-replication.
Outbound data transfer	per GB	Bytes leaving Azure to internet.

Optimization tips

Common ways to reduce azurerm_redis_cache cost without changing the workload.

Use Basic tier for non-production

About 50%

Basic is half the price of Standard at the same size. For dev/staging/test where there's no SLA requirement, Basic is sufficient.

Stay on Standard unless you need Premium features

Workload-dependent, often 50%+

Premium pricing is dramatically higher per GB than Standard. Only choose Premium if you specifically need clustering, persistence, VNet integration, or geo-replication.

Right-size by actual memory usage

About 50% per level reduction

Azure Cache for Redis exposes UsedMemory in Azure Monitor. If consistently below 40% of cache size, drop one capacity level (C2 to C1, C3 to C2, etc.).

Buy Reserved Capacity for production

30-55%

1-year reserved cuts prices by 30%; 3-year by 55%. Right for stable production caches that won't move.

Use Standard SKU shards over Premium clustering for medium scale

Up to 70%

Premium clustering supports up to 1.2 TB. For caches under 53 GB total, Standard with application-level sharding (or multiple smaller caches) is much cheaper than Premium clustering.

FAQ

Do I need Premium for production?

Only if you need clustering (>53 GB), data persistence to disk, VNet integration, or geo-replication. For most workloads, Standard with its 99.9% SLA is sufficient. Premium is sometimes 5x the cost of equivalent Standard.

What about Enterprise tier?

Enterprise (sku_name = 'Enterprise') is Redis Inc.'s commercial tier with Redis Modules (JSON, Search, Bloom, etc.) and Active-Active geo-replication. Right for teams standardizing on Redis Enterprise commercial features. Significantly more expensive.

How does c3x compute cache size?

c3x reads capacity (an index 0-6 for C family, 1-5 for P family) and family. It maps to the underlying size and applies the per-hour rate for the SKU.