Verified 2026 API Rates • Prompt Caching & Batch ROI

OpenAI: GPT-6.1 Terra vs SpaceXAI: Grok 4.6

Compare real-world API costs for OpenAI: GPT-6.1 Terra ($1/$5) vs SpaceXAI: Grok 4.6 ($2/$6). Calculate Prompt Caching ROI & Batch API savings.

OpenAI: GPT-6.1 Terra saves up to 50% on base input tokens
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
xAI

SpaceXAI: Grok 4.6

grok-4.6
Base Input Rate
$2.00 / 1M
Output Rate
$6.00 / 1M
Prompt Cache Read
$0.50 / 1M (-75%)
Cache Write Surcharge
$0.00 (Free write)
Batch API Discount
-20% Off
Context Window
500k tokens
Quality Index (MMLU)
88
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 OpenAI: GPT-6.1 Terra and SpaceXAI: Grok 4.6:

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.

SpaceXAI: Grok 4.6 Caching Profile-75% read discount

  • Cached Read Price: $0.500 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
OpenAI: GPT-6.1 Terra$1.00 / $5.00$0.50 / $2.50 (-50%)24 Hours max (typically 30m - 2h)Bulk evaluation, dataset labeling, background summarization
SpaceXAI: Grok 4.6$2.00 / $6.00$1.00 / $3.00 (-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.

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.

SpaceXAI: Grok 4.6 Context Capacity

Provides a 500k token context window with a maximum output limit of 450k 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.

OpenAI: GPT-6.1 Terra:$300.63/mo
SpaceXAI: Grok 4.6:$546.25/mo
Delta Savings:-$245.63 (45%)
Architecture Verdict:OpenAI: GPT-6.1 Terra delivers 45% lower monthly spend ($245.63/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.

OpenAI: GPT-6.1 Terra:$174.36/mo
SpaceXAI: Grok 4.6:$315.25/mo
Delta Savings:-$140.89 (45%)
Architecture Verdict:OpenAI: GPT-6.1 Terra delivers 45% lower monthly spend ($140.89/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).

OpenAI: GPT-6.1 Terra:$616.25/mo
SpaceXAI: Grok 4.6:$1620.00/mo
Delta Savings:-$1003.75 (62%)
Architecture Verdict:OpenAI: GPT-6.1 Terra delivers 62% lower monthly spend ($1003.75/mo savings) for this workload profile.
ミリ秒単位の対話型シミュレータ

OpenAI: GPT-6.1 Terra vs SpaceXAI: Grok 4.6

エンタープライズの代表的な3大ユースケース(RAG検索、コーディングAgent、バッチ抽出)で精密試算:

Live 50ms Engine
月間リクエスト数 (Requests)100,000
入力トークン数/回 (Input Tokens)4,000
出力トークン数/回 (Output Tokens)1,000
Prompt キャッシュヒット率 (Cache Hit)70%
Batch API 分流比率0%
OpenAI: GPT-6.1 Terra 安価

月間推定削減額

OpenAI: GPT-6.1 Terra$634.00$6.340// 1,000リクエスト
vs
SpaceXAI: Grok 4.6$980.00$9.800// 1,000リクエスト
Developer FAQs

Frequently Asked Questions: OpenAI: GPT-6.1 Terra vs SpaceXAI: Grok 4.6

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

1Which model is cheaper overall: OpenAI: GPT-6.1 Terra or SpaceXAI: Grok 4.6?

At base pricing, OpenAI: GPT-6.1 Terra costs $1/1M input and $5/1M output, while SpaceXAI: Grok 4.6 costs $2/1M input and $6/1M 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 OpenAI: GPT-6.1 Terra vs SpaceXAI: Grok 4.6?

OpenAI: GPT-6.1 Terra offers a 95% read discount ($0.05/1M), whereas SpaceXAI: Grok 4.6 provides a 75% read discount ($0.5/1M). High cache hit ratios (>70%) significantly compress the cost delta in agentic and RAG architectures.

3Can I use Batch API with OpenAI: GPT-6.1 Terra or SpaceXAI: Grok 4.6 to save 50%?

OpenAI: GPT-6.1 Terra supports 50% batch offload discounts for asynchronous 24-hour turnaround tasks. SpaceXAI: Grok 4.6 supports 50% batch discounts.

4What are the context window limits and tiered pricing rules for OpenAI: GPT-6.1 Terra vs SpaceXAI: Grok 4.6?

OpenAI: GPT-6.1 Terra features a 1,050k context window with flat per-token pricing. In comparison, SpaceXAI: Grok 4.6 supports 500k tokens with flat per-token pricing.