Verified 2026 API Rates • Prompt Caching & Batch ROI

GPT-4o (Omni) vs OpenAI: GPT-6.1 Terra

Compare real-world API costs for GPT-4o (Omni) ($2.5/$10) vs OpenAI: GPT-6.1 Terra ($1/$5). Calculate Prompt Caching ROI & Batch API savings.

OpenAI: GPT-6.1 Terra saves up to 60% on base input tokens
OpenAI

GPT-4o (Omni)

gpt-4o
Base Input Rate
$2.50 / 1M
Output Rate
$10.00 / 1M
Prompt Cache Read
$1.25 / 1M (-50%)
Cache Write Surcharge
$0.00 (Free write)
Batch API Discount
-50% Off
Context Window
128k tokens
Quality Index (MMLU)
88.7
OpenAI

OpenAI: GPT-6.1 Terra

gpt-6.1-terra
Base Input Rate
$1.00 / 1M
Output Rate
$5.00 / 1M
Prompt Cache Read
$0.050 / 1M (-95%)
Cache Write Surcharge
$0.00 (Free write)
Batch API Discount
-50% Off
Context Window
1,050k tokens
Quality Index (MMLU)
87.8
Differential Module 1

Prompt Caching ROI & Write Surcharge Break-Even Analysis

Prompt caching drastically reduces input token costs for static prefixes like system prompts, tool schemas, and document chunks. Compare caching mechanisms between GPT-4o (Omni) and OpenAI: GPT-6.1 Terra:

GPT-4o (Omni) Caching Profile-50% read discount

  • Cached Read Price: $1.250 per 1M tokens.
  • Write Surcharge: $0.00 (automatic caching with zero write penalty).
  • Minimum Cache Prefix: 1,024 tokens.
  • Amortization Rule: Immediate net savings from first cached read call.

OpenAI: GPT-6.1 Terra Caching Profile-95% read discount

  • Cached Read Price: $0.050 per 1M tokens.
  • Write Surcharge: $0.00 (automatic caching with zero write penalty).
  • Minimum Cache Prefix: 1,024 tokens.
  • Amortization Rule: Immediate net savings from first cached read call.
Differential Module 2

Batch API 50% Discount Offload vs Real-Time SLA

Asynchronous Batch APIs cut total token expenditures in half (50% off input and output) in exchange for non-realtime execution (up to 24-hour turnaround SLA).

Model / ArchitectureStandard Input / OutputBatch 50% Off Input / OutputTurnaround SLAOptimal Use Cases
GPT-4o (Omni)$2.50 / $10.00$1.25 / $5.00 (-50%)24 Hours max (typically 30m - 2h)Bulk evaluation, dataset labeling, background summarization
OpenAI: GPT-6.1 Terra$1.00 / $5.00$0.50 / $2.50 (-50%)24 Hours max (typically 30m - 2h)Offline document translation, embedding backfills, test suites
Differential Module 3

Context Window Escalation & Tiered Pricing Architecture

Massive context windows allow ingesting entire repositories or books, but pricing models differ drastically between flat-rate vendors and tiered step-up pricing.

GPT-4o (Omni) Context Capacity

Provides a 128k token context window with a maximum output limit of 16.384k tokens.✓ Flat-rate billing across all prompt sizes up to max context ceiling.

OpenAI: GPT-6.1 Terra Context Capacity

Provides a 1,050k token context window with a maximum output limit of 128k tokens.✓ Flat-rate billing across all prompt sizes up to max context ceiling.

Quill Strategic Content

Real-World Production Scenarios: Monthly Spend Projections

Pre-computed monthly engineering bill projections across 3 representative enterprise application workloads:

Scenario 1

RAG Knowledge Base & Enterprise Search

100,000 queries/month, 3,500 input tokens (system + 5 retrieved chunks), 400 output tokens, 75% prompt cache hit rate.

GPT-4o (Omni):$946.88/mo
OpenAI: GPT-6.1 Terra:$300.63/mo
Delta Savings:-$646.25 (68%)
Architecture Verdict:OpenAI: GPT-6.1 Terra delivers 68% lower monthly spend ($646.25/mo savings) for this workload profile.
Scenario 2

Multi-Turn Coding Agent & ReAct Loops

25,000 tasks/month, 8,000 input tokens (accumulating conversation context & tool schemas), 1,200 output tokens, 85% cache hit rate.

GPT-4o (Omni):$543.44/mo
OpenAI: GPT-6.1 Terra:$174.36/mo
Delta Savings:-$369.08 (68%)
Architecture Verdict:OpenAI: GPT-6.1 Terra delivers 68% lower monthly spend ($369.08/mo savings) for this workload profile.
Scenario 3

High-Throughput Offline Data Extraction

500,000 records/month, 1,500 input tokens, 250 output tokens, 100% batch offload (24-hour turnaround SLA).

GPT-4o (Omni):$1468.75/mo
OpenAI: GPT-6.1 Terra:$616.25/mo
Delta Savings:-$852.50 (58%)
Architecture Verdict:OpenAI: GPT-6.1 Terra delivers 58% lower monthly spend ($852.50/mo savings) for this workload profile.
Real-Time Interactive Engine

GPT-4o (Omni) vs OpenAI: GPT-6.1 Terra

Pre-computed monthly engineering bill projections across 3 representative enterprise application workloads:

Live 50ms Engine
Monthly Requests100,000
Input Tokens / Req4,000
Output Tokens1,000
Prompt Cache Hit Rate70%
Batch API Offload0%
OpenAI: GPT-6.1 Terra Cheaper

saves approximately

GPT-4o (Omni)$1,650.00$16.500// 1k reqs
vs
OpenAI: GPT-6.1 Terra$634.00$6.340// 1k reqs
Developer FAQs

Frequently Asked Questions: GPT-4o (Omni) vs OpenAI: GPT-6.1 Terra

Authoritative answers on API rate limits, pricing math, break-even thresholds, and architectural migration.

1Which model is cheaper overall: GPT-4o (Omni) or OpenAI: GPT-6.1 Terra?

At base pricing, GPT-4o (Omni) costs $2.5/1M input and $10/1M output, while OpenAI: GPT-6.1 Terra costs $1/1M input and $5/1M output. The cheaper option depends on your input-to-output token ratio and whether prompt caching or batch discounts are utilized.

2How does Prompt Caching impact the cost of GPT-4o (Omni) vs OpenAI: GPT-6.1 Terra?

GPT-4o (Omni) offers a 50% read discount ($1.25/1M), whereas OpenAI: GPT-6.1 Terra provides a 95% read discount ($0.05/1M). High cache hit ratios (>70%) significantly compress the cost delta in agentic and RAG architectures.

3Can I use Batch API with GPT-4o (Omni) or OpenAI: GPT-6.1 Terra to save 50%?

GPT-4o (Omni) supports 50% batch offload discounts for asynchronous 24-hour turnaround tasks. OpenAI: GPT-6.1 Terra supports 50% batch discounts.

4What are the context window limits and tiered pricing rules for GPT-4o (Omni) vs OpenAI: GPT-6.1 Terra?

GPT-4o (Omni) features a 128k context window with flat per-token pricing. In comparison, OpenAI: GPT-6.1 Terra supports 1,050k tokens with flat per-token pricing.