Verified 2026 API Rates • Prompt Caching & Batch ROI

Gemini 1.5 Flash vs OpenAI: GPT-6 Astra

Compare real-world API costs for Gemini 1.5 Flash ($0.075/$0.3) vs OpenAI: GPT-6 Astra ($10/$50). Calculate Prompt Caching ROI & Batch API savings.

Gemini 1.5 Flash saves up to 99% on base input tokens
Google

Gemini 1.5 Flash

gemini-1.5-flash
Base Input Rate
$0.07 / 1M
Output Rate
$0.30 / 1M
Prompt Cache Read
$0.019 / 1M (-75%)
Cache Write Surcharge
$0.00 (Free write)
Batch API Discount
-50% Off
Context Window
1,000k tokens
Quality Index (MMLU)
78.9
OpenAI

OpenAI: GPT-6 Astra

gpt-6-astra
Base Input Rate
$10.00 / 1M
Output Rate
$50.00 / 1M
Prompt Cache Read
$1.00 / 1M (-90%)
Cache Write Surcharge
$0.00 (Free write)
Batch API Discount
-50% Off
Context Window
1,050k 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 Gemini 1.5 Flash and OpenAI: GPT-6 Astra:

Gemini 1.5 Flash Caching Profile-75% read discount

  • Cached Read Price: $0.019 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 Astra Caching Profile-90% read discount

  • Cached Read Price: $1.000 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
Gemini 1.5 Flash$0.07 / $0.30$0.04 / $0.15 (-50%)24 Hours max (typically 30m - 2h)Bulk evaluation, dataset labeling, background summarization
OpenAI: GPT-6 Astra$10.00 / $50.00$5.00 / $25.00 (-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.

Gemini 1.5 Flash Context Capacity

Provides a 1,000k token context window with a maximum output limit of 8.192k tokens.⚠️ Note: Prompts exceeding 128k tokens double in price to $0.15/1M in and $0.6/1M out.

OpenAI: GPT-6 Astra 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.

Gemini 1.5 Flash:$23.48/mo
OpenAI: GPT-6 Astra:$3137.50/mo
Delta Savings:-$3114.02 (99%)
Architecture Verdict:Gemini 1.5 Flash delivers 99% lower monthly spend ($3114.02/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.

Gemini 1.5 Flash:$13.35/mo
OpenAI: GPT-6 Astra:$1822.25/mo
Delta Savings:-$1808.90 (99%)
Architecture Verdict:Gemini 1.5 Flash delivers 99% lower monthly spend ($1808.90/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).

Gemini 1.5 Flash:$42.66/mo
OpenAI: GPT-6 Astra:$6200.00/mo
Delta Savings:-$6157.34 (99%)
Architecture Verdict:Gemini 1.5 Flash delivers 99% lower monthly spend ($6157.34/mo savings) for this workload profile.
ミリ秒単位の対話型シミュレータ

Gemini 1.5 Flash vs OpenAI: GPT-6 Astra

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%
Gemini 1.5 Flash 安価

月間推定削減額

Gemini 1.5 Flash$44.25$0.442// 1,000リクエスト
vs
OpenAI: GPT-6 Astra$6,480.00$64.800// 1,000リクエスト
Developer FAQs

Frequently Asked Questions: Gemini 1.5 Flash vs OpenAI: GPT-6 Astra

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

1Which model is cheaper overall: Gemini 1.5 Flash or OpenAI: GPT-6 Astra?

At base pricing, Gemini 1.5 Flash costs $0.075/1M input and $0.3/1M output, while OpenAI: GPT-6 Astra costs $10/1M input and $50/1M 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 Gemini 1.5 Flash vs OpenAI: GPT-6 Astra?

Gemini 1.5 Flash offers a 75% read discount ($0.01875/1M), whereas OpenAI: GPT-6 Astra provides a 90% read discount ($1/1M). High cache hit ratios (>70%) significantly compress the cost delta in agentic and RAG architectures.

3Can I use Batch API with Gemini 1.5 Flash or OpenAI: GPT-6 Astra to save 50%?

Gemini 1.5 Flash supports 50% batch offload discounts for asynchronous 24-hour turnaround tasks. OpenAI: GPT-6 Astra supports 50% batch discounts.

4What are the context window limits and tiered pricing rules for Gemini 1.5 Flash vs OpenAI: GPT-6 Astra?

Gemini 1.5 Flash features a 1,000k context window with tiered escalation above 128k tokens. In comparison, OpenAI: GPT-6 Astra supports 1,050k tokens with flat per-token pricing.