microsoft-foundry/quota/references/ptu-guide.md

Provisioned Throughput Units (PTU) Guide

Table of Contents: Understanding PTU vs Standard TPM · When to Use PTU · PTU Capacity Planning · Deploy Model with PTU · Request PTU Quota Increase · Understanding Region and Deployment Quotas · External Resources

Understanding PTU vs Standard TPM

Microsoft Foundry offers two quota types:

Standard TPM (Tokens Per Minute)

• Pay-as-you-go model, charged per token
• Each deployment consumes capacity units (e.g., 10K TPM, 50K TPM)
• Total regional quota shared across all deployments
• Subject to rate limiting during high demand (429 errors possible)
• Best for: Variable workloads, development, testing, bursty traffic

Provisioned Throughput Units (PTU)

• Monthly commitment for guaranteed throughput
• No rate limiting, consistent latency
• Measured in PTU units (not TPM)
• Best for: Predictable, high-volume production workloads
• More cost-effective when consistent token usage justifies monthly commitment

When to Use PTU

Factor	Standard (TPM)	Provisioned (PTU)
Best For	Variable workloads, development, testing	Predictable production workloads
Pricing	Pay-per-token	Monthly commitment (hourly rate per PTU)
Rate Limits	Yes (429 errors possible)	No (guaranteed throughput)
Latency	Variable	Consistent
Cost Decision	Lower upfront commitment	More economical for consistent, high-volume usage
Flexibility	Scale up/down instantly	Requires planning and commitment
Use Case	Prototyping, bursty traffic	Production apps, high-volume APIs

Use PTU when:

• Consistent, predictable token usage where monthly commitment is cost-effective
• Need guaranteed throughput (no 429 rate limit errors)
• Require consistent latency with performance SLA
• High-volume production workloads with stable traffic patterns

Decision Guidance: Compare your current pay-as-you-go costs with PTU pricing. PTU may be more economical when consistent usage justifies the monthly commitment.

PTU Capacity Planning

Official Calculation Methods

Agent Instruction: Only present official Azure capacity calculator methods below. Do NOT generate or suggest estimated PTU formulas, TPM-per-PTU conversion tables, or reference deprecated calculators (oai.azure.com/portal/calculator).

Calculate PTU requirements using these official methods:

Method 1: Microsoft Foundry Portal

1. Navigate to Microsoft Foundry portal
2. Go to Operate → Quota
3. Select Provisioned throughput unit tab
4. Click Capacity calculator button
5. Enter workload parameters (model, tokens/call, RPM, latency target)
6. Calculator returns exact PTU count needed

Method 2: Using Azure REST API

# Calculate required PTU capacity
curl -X POST "https://management.azure.com/subscriptions/<subscription-id>/providers/Microsoft.CognitiveServices/calculateModelCapacity?api-version=2024-10-01" \
  -H "Authorization: Bearer <access-token>" \
  -H "Content-Type: application/json" \
  -d '{
    "model": {
      "format": "OpenAI",
      "name": "gpt-4o",
      "version": "2024-05-13"
    },
    "workload": {
      "requestPerMin": 100,
      "tokensPerMin": 50000,
      "peakRequestsPerMin": 150
    }
  }'

Deploy Model with PTU

Step 1: Calculate PTU Requirements

Use the official capacity calculator methods above to determine required PTU capacity.

Step 2: Deploy with PTU

# Deploy model with calculated PTU capacity
az cognitiveservices account deployment create \
  --name <resource-name> \
  --resource-group <rg> \
  --deployment-name gpt-4o-ptu-deployment \
  --model-name gpt-4o \
  --model-version "2024-05-13" \
  --model-format OpenAI \
  --sku-name ProvisionedManaged \
  --sku-capacity 100

# Check PTU deployment status
az cognitiveservices account deployment show \
  --name <resource-name> \
  --resource-group <rg> \
  --deployment-name gpt-4o-ptu-deployment

Key Differences from Standard TPM:

• SKU name: ProvisionedManaged (not Standard)
• Capacity: Measured in PTU units (not K TPM)
• Billing: Monthly commitment regardless of usage
• No rate limiting (guaranteed throughput)

Request PTU Quota Increase

PTU quota is separate from TPM quota and requires specific justification:

1. Navigate to Azure Portal → Foundry resource → Quotas
2. Select Provisioned throughput unit tab
3. Identify model needing PTU increase (e.g., "GPT-4o PTU")
4. Click Request quota increase
5. Fill form:
   • Model name
   • Requested PTU quota
   • Include capacity calculator results in business justification
   • Explain workload characteristics (volume, latency requirements)
6. Submit and monitor status

Processing Time: Typically 3-5 business days (longer than standard quota requests) Note: PTU quota requests typically require stronger business justification due to commitment nature

Alternative: Deploy to different region with available PTU quota

Understanding Region and Deployment Quotas

Region Quota

• Maximum PTU capacity available in an Azure region
• Varies by model type (GPT-4, GPT-4o, etc.)
• Shared across subscription resources in same region
• Separate from TPM quota (you have both TPM and PTU quotas)

Deployment Slots

• Number of concurrent model deployments allowed
• Typically 10-20 slots per resource
• Each PTU deployment uses one slot (same as TPM deployments)
• Deployment count limit is independent of capacity

External Resources

• Understanding PTU Costs
• What Is Provisioned Throughput
• Calculate Model Capacity API
• PTU Overview