Render Scaling

---
name: render-scaling
description: >-
  Scales Render services—configures autoscaling targets, chooses instance
  types, sets manual instance counts, and optimizes cost. Use when the user
  needs to handle more traffic, set up autoscaling, pick the right instance
  type, reduce costs, or troubleshoot scaling behavior like slow scale-down or
  stuck instances.
license: MIT
compatibility: Render web services, private services, and background workers
metadata:
  author: Render
  version: "1.0.0"
  category: operations
---

# Render Scaling

This skill covers how to scale **Web Services**, **Private Services**, and **Background Workers** on Render: manual instance counts, **Professional+** autoscaling, plan (instance type) choices, and platform limits. Deeper tables and tuning guidance live under `references/`.

## When to Use

- Setting or changing **instance count** (Dashboard, CLI, API, or Blueprint)
- Configuring **autoscaling** (min/max, CPU and memory targets)
- Choosing **vertical** (plan) vs **horizontal** (more instances) scaling
- Understanding **constraints** (disks, static sites, cron/workflows, 100-instance cap)
- **Cost** implications of multi-instance and per-second billing
- **Blueprint** fields: `numInstances`, `scaling`, `plan`

## Manual Scaling

- Set **instance count** from **1 to 100** via the **Dashboard**, **CLI**, or **API**.
- **All instances share the same instance type** (plan); you cannot mix plans on one service.
- Changes apply **immediately**: Render **provisions** new instances and **deprovisions** excess capacity as needed.

## Autoscaling

- Available on **Professional and higher** workspaces only.
- Configure **minimum** and **maximum** instances and targets for **CPU** and/or **memory** utilization (**1–90%** each).
- **At least one metric must be enabled** (CPU or memory). If **both** CPU and memory autoscaling toggles are **off**, autoscaling is **disabled**.
- If **both** manual instance settings and autoscaling are configured, **autoscaling wins**—manual count does not override the scaling policy in effect.

## Autoscaling Formula

Render computes a candidate instance count from utilization vs target:

`new_instances = ceil(current_instances * (current_utilization / target_utilization))`

- When **both** CPU and memory targets are set, the platform uses the **larger** of the two `new_instances` values (the more conservative scale-out).

## Scaling Constraints

| Constraint | Behavior |
|------------|----------|
| **Per service** | **Maximum 100** instances |
| **Persistent disk** | **Cannot** scale to multiple instances—**single instance only** |
| **Static sites** | **Not** scalable (served by CDN) |
| **Cron jobs & Workflows** | Scaling model **does not apply** (different execution model) |

## Scale-Down Behavior

- **Scale-up** is **immediate** when utilization supports it.
- **Scale-down** waits **a few minutes** after conditions allow reduction (**spike protection**). This reduces **flapping** from brief load spikes.

## Instance Types

- In Blueprints, the instance type is the **`plan`** field (e.g. `standard`, `pro`).
- Options span **free** / **starter** through **standard**, **pro**, **pro_plus**, **pro_max**, **pro_ultra**—each with defined **CPU** and **RAM** (see `references/instance-types.md`).

### Vertical vs Horizontal

| Need | Approach | When |
|------|----------|------|
| More throughput | **Horizontal** (add instances) | Stateless services, request-based workloads |
| More RAM/CPU per process | **Vertical** (upgrade **plan**) | Memory-intensive or single-threaded apps |
| Both | **Combine** | Right-size plan, then scale out for traffic |

## Cost Patterns

- **Per-second billing**; **no separate fee** for scaling actions.
- You pay roughly for **compute time × number of running instances** (see [Render pricing](https://render.com/pricing) for current rates).
- **Right-size** by monitoring **CPU and memory** utilization (see **render-monitor**).

## Blueprint Configuration

**Manual instance count:**

```yaml
numInstances: 3
```

**Autoscaling:**

```yaml
scaling:
  minInstances: 1
  maxInstances: 10
  targetCPUPercent: 70
  targetMemoryPercent: 80
```

**Instance type (plan):**

```yaml
plan: standard
```

Do not rely on `numInstances` to cap autoscaling when a `scaling` block is present—**autoscaling takes precedence**. Preview behavior for scaling is detailed in `references/autoscaling-guide.md`.

## References

| Topic | File |
|--------|------|
| Plan names, CPU/RAM, flexible vs non-flexible, free tier | `references/instance-types.md` |
| Enabling autoscaling, targets, min/max, mistakes, previews | `references/autoscaling-guide.md` |

## Related Skills

- **render-web-services** — Web Service settings, disks, deploy lifecycle
- **render-background-workers** — Worker-specific configuration and scaling context
- **render-blueprints** — Full Blueprint schema and field reference
- **render-monitor** — Metrics, logs, and utilization for right-sizing