Redis is an open-source, in-memory data store that acts as a persistent object cache for WordPress. Instead of rebuilding the same database queries on every page load, Redis stores the results in memory so WordPress can retrieve them instantly. On Kinsta, Redis is available as a paid add-on suited to dynamic sites where page caching alone is not enough.
Redis is Layer 3 of Kinsta's three-layer caching stack (after the edge CDN and the built-in server page cache). For the order to use those layers and when Redis is the right next step, see our Kinsta WordPress optimization guide.
When Does Redis Help Most?
Kinsta includes full-page caching on all plans, which handles most static content well. Redis becomes valuable for sites where the cached page version changes frequently or is bypassed entirely:
- WooCommerce stores: cart, checkout, and account pages are excluded from page cache; Redis reduces the database load on these uncached pages
- Membership sites: logged-in users see personalised content that bypasses page cache; Redis keeps database queries fast
- Forums and community platforms: high read/write frequency makes object caching effective
Redis is less useful for a simple WordPress blog or brochure site where full-page caching already handles the load. To identify whether slow database queries are the actual bottleneck before enabling Redis, use the Kinsta APM tool to pinpoint which queries are causing slowdowns.
What Does Redis Cost on Kinsta?
Kinsta offers Redis as a paid add-on billed per site per month. As of 2024, Redis is typically listed in the $25-$100 per month range depending on your plan tier, but the exact price is shown in your MyKinsta billing area before you confirm the request. Only users with billing permissions (Company Owner, Company Admin, or Company Billing role) can request paid add-ons. For most WooCommerce and membership sites, the Redis cost is smaller than the performance benefit it provides in reduced server load and faster response times on dynamic pages.
How to Enable Redis Object Cache on Kinsta
Step 1 - Request the Add-On
Log in to MyKinsta and open a support chat. Request to have Redis enabled for the specific site you want it on, naming the site clearly. Kinsta’s support team enables the add-on, adds the billing subscription, and confirms when it is live.
Step 2 - Install the Redis Object Cache Plugin
Once Kinsta confirms Redis is active on your site, log in to your WordPress dashboard. Go to Plugins > Add New and search for Redis Object Cache (by Till Kruss). Install and activate it.
Step 3 - Enable the Object Cache
Go to Settings > Redis in the WordPress dashboard. Click Enable Object Cache. The plugin creates a wp-content/object-cache.php drop-in file and connects to the Redis instance Kinsta provisioned. The status should change to Connected within a few seconds.
If the status shows an error, check with Kinsta support that the Redis add-on is active and that the correct credentials are set in the plugin settings.
Step 4 - Verify Redis Is Working
Check the Redis status in two places:
- MyKinsta: go to your site, then the Info tab; the Redis section shows whether the add-on is active
- Plugin dashboard: the Redis Object Cache plugin shows cache hits, misses, and connection status under Settings > Redis
A rising cache hit rate over time confirms Redis is intercepting repeated database queries. A hit rate below 50% after a day of traffic may indicate the site is not a strong Redis candidate.
How to Flush the Redis Cache on Kinsta
Flushing the Redis cache clears all stored objects and forces WordPress to rebuild them from the database on the next request. Do this after significant WordPress changes (bulk content updates, plugin activations, theme changes) to ensure the cache reflects the current state of the database.
There are three ways to flush Redis on Kinsta:
- Plugin dashboard: Go to Settings > Redis in WordPress. The plugin dashboard shows a Flush Cache button. Click it to clear all cached objects immediately. This is the simplest method and requires no SSH access.
- WP-CLI (SSH): SSH into your Kinsta server using the credentials in MyKinsta (Info > SSH), then run:
wp redis flush. This flushes the Redis object cache instantly and is useful when you need to confirm the flush happened programmatically or as part of a deployment script. - MyKinsta cache clear: In MyKinsta, go to your site and click Clear Cache. This clears Kinsta’s full-page Nginx cache. Depending on your Kinsta plan and configuration, it may also flush the Redis object cache, but for a guaranteed Redis flush, use the plugin button or WP-CLI.
Redis and WordPress Caching Plugins on Kinsta
Redis Object Cache and WordPress caching plugins (WP Rocket, W3 Total Cache, LiteSpeed Cache) serve different purposes and can work together.
What Redis does: caches the results of individual database queries and WordPress object cache calls (such as widget data, menu structures, and user meta). It reduces repeated database hits for the same data.
What Kinsta’s built-in page cache does: caches fully rendered HTML pages at the Nginx server level. Anonymous visitors receive the cached HTML without WordPress running at all. This is what Kinsta provides on all plans.
They work at different layers. Full-page caching serves anonymous visitors HTML without touching the database. Redis serves logged-in users and dynamic pages (WooCommerce, memberships) by reducing the database queries that do run.
If you are using WP Rocket or a similar plugin on Kinsta, you should typically disable its page caching feature (since Kinsta’s Nginx cache already handles this and running both can cause conflicts or stale content). Keep the asset optimisation features in WP Rocket active: CSS/JS minification, image lazy loading, and preloading. The Redis add-on fills the gap for uncached dynamic pages that page caching cannot help with.
Troubleshooting Redis Connection Errors on Kinsta
If the Redis Object Cache plugin shows Disconnected or a connection error after setup, work through these steps:
- Confirm the add-on is active: In MyKinsta, go to your site’s Info tab and check the Redis section. If it shows inactive, contact Kinsta support to re-enable it.
- Check plugin credentials: Under Settings > Redis, verify the host and port match what Kinsta provisioned for your site. Kinsta typically provides these automatically, but they can become mismatched after a site migration or environment clone.
- Reactivate the plugin: Deactivate and reactivate the Redis Object Cache plugin from the WordPress plugins list. Reactivation re-creates the
wp-content/object-cache.phpdrop-in file, which can fix connection issues caused by a corrupted or outdated drop-in. - Check staging vs production: If you cloned your live site to staging with Redis enabled, the staging environment needs its own Redis add-on or the plugin will show Disconnected. Either request a separate Redis add-on for staging, or disable the plugin on the staging environment.
- Contact Kinsta support: If none of the above resolves the issue, open a support chat in MyKinsta with the site name and the error message from the plugin. Kinsta can inspect the Redis configuration from their end.
How to Check Redis Memory Usage and Cache Hit Rate on Kinsta
Once Redis is running, two numbers tell you whether it is actually helping: the hit rate and memory consumption. Checking them regularly lets you catch a misconfiguration early or confirm the add-on is worth the cost.
Hit Rate
The Redis Object Cache plugin shows the hit rate on its dashboard at Settings > Redis. The hit rate is the percentage of cache reads served from Redis rather than the database. A healthy hit rate for a WooCommerce or membership site is typically 60% or higher after the cache has warmed up over a day of traffic. A rate below 30% after 24 hours suggests that Redis is not well-suited to this site or that the cache is being flushed too frequently.
To check hit rate via WP-CLI (SSH into your Kinsta server and run):
wp redis info
This prints the full Redis server stats including keyspace_hits, keyspace_misses, and memory usage. Divide hits by (hits + misses) to get the hit rate as a percentage.
Memory Usage
Redis is billed by the memory allocated to it. Kinsta provisions a fixed amount per site, which you can confirm in MyKinsta > your site > Info. The used_memory_human value from wp redis info shows how much of that allocation is in use.
If used_memory is consistently near the allocated ceiling, Redis may be evicting older objects before they can be served from cache, which reduces the effective hit rate. You can either reduce the cache expiry time to keep fewer objects in memory at once, or contact Kinsta support to discuss increasing the Redis memory allocation for your site.
When to Remove Redis
If the hit rate stays below 30% after a week and the site does not rely heavily on dynamic uncached pages, the add-on cost may not be justified. Remove it by contacting Kinsta support, who will disable the add-on and remove the billing subscription.
Redis vs Kinsta Page Cache: How They Work Together
Kinsta uses a full-page cache (powered by Nginx FastCGI caching) that stores a complete HTML snapshot of each page and serves it without touching PHP or the database at all. Redis Object Cache is different: it stores the results of database queries in memory so PHP does not have to run the same queries repeatedly.
The two caches serve different visitors:
- Full-page cache serves anonymous visitors (people who are not logged in). They get a cached HTML file served in under 50 ms, with no PHP or database involved.
- Redis Object Cache helps logged-in users (admin users, WooCommerce customers with items in cart, members) who bypass the full-page cache by design. For these users, Redis reduces the time PHP spends querying the database on every page load.
If your site is a static blog or brochure site with few logged-in users, the full-page cache does most of the work and Redis adds minimal benefit. If you run WooCommerce, a membership site, or a site where many users are logged in simultaneously, Redis has a measurable impact on performance because those users are never served the full-page cached version. Both caches can run simultaneously. Enabling Redis does not disable or replace the Kinsta page cache.
Notes About Redis on Kinsta
If you have both a staging and live environment, the staging site needs its own Redis add-on to test with Redis enabled. Alternatively, delete the staging site if it is not in use to avoid unnecessary billing.
To remove Redis, contact Kinsta support. They will remove the add-on and the subscription charge. If there was unused time remaining on the billing cycle, Kinsta applies a refund based on their refund policy.
Final Word: How to Use Redis Object Cache on WordPress via Kinsta
Redis is a worthwhile add-on for dynamic WordPress sites on Kinsta where page caching does not cover all requests, particularly WooCommerce, membership, and forum sites. The setup takes under ten minutes: request the add-on via support, install the Redis Object Cache plugin, enable it, and confirm the status shows Connected. When you need to clear the cache, use the plugin’s Flush Cache button or run wp redis flush via SSH.
If Redis does not connect after setup, enabling WordPress debug mode in MyKinsta reveals the specific PHP error preventing the connection.
