AWS Cost Allocation

Amazon Polly Pricing and Cost Optimization

Top 5 Proven Strategies to Reduce Amazon Polly Costs
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Amazon Polly supports over 60 languages and 30+ voices! It can generate lifelike speech in seconds, helping you create voice apps with natural-sounding voices in multiple accents worldwide.

Amazon Polly is a powerful text-to-speech (TTS) service that helps developers create natural-sounding voice applications. Whether you're building an interactive assistant, an e-learning platform, or an audiobook service, Polly offers high-quality speech synthesis at scale. However, understanding its pricing model and finding ways to reduce costs can make a big difference in your budget.

In this guide, we’ll break down Amazon Polly’s pricing structure, explore key cost factors, and share practical tips to help you optimize expenses while making the most of its capabilities.

Amazon Polly Pricing Structure

AWS text-to-speech pricing includes Standard, Neural, Long-Form, and Generative Voices, with Free Tier allowances for the first 12 months. AWS GovCloud (US) has slightly higher rates. The pricing structure helps users understand different voice types and their associated costs.

Pricing Table

Voice Type Price per 1M Characters Free Tier (First 12 Months)
Standard Voices $4.00 5 million characters/month
Neural Voices $16.00 1 million characters/month
Long-Form Voices $100.00 500k characters/month
Generative Voices $30.00 100k characters/month

AWS GovCloud (US) Pricing

Voice Type Price per 1M Characters
Standard Voices $4.80
Neural Voices $19.20

Pricing Example

A digital publishing company in the US East (N. Virginia) region is converting its latest novel into an audiobook using Amazon Polly. The book contains 120,000 characters, and the company chooses Neural TTS for its natural and high-quality speech output.​

Pricing Calculation:

  • Text Length: 120,000 characters​
  • Estimated Speech Duration: Approximately 2 hours 45 minutes​
  • Neural TTS Cost: $16 per 1 million characters​

Total Cost Calculation:

(120,000 ÷ 1,000,000) × $16 = $1.92​

Alternative Pricing Options:

  • Standard TTS: $0.48​
  • Long-Form TTS: $12.00​

By analyzing these pricing models, publishers can choose the most cost-effective option based on their budget and desired audio quality.​

Comparison of Amazon Polly Voice Options

Feature Standard Voices Neural Voices Long-Form Voices Generative Voice
Use Case Basic applications, notifications Premium applications, virtual assistants, audiobooks Extended content like podcasts, lectures, audiobooks Real-time, personalized, and interactive applications
Quality Clear and understandable, but less natural More realistic, human-like tone with emotional depth High-quality, natural-sounding speech suitable for long-form content Context-sensitive, highly dynamic and interactive
Best For Simpler tasks where high quality isn’t necessary Applications needing high-quality, lifelike speech Projects requiring extended speech synthesis Conversational AI, interactive agents, dynamic narration
Example Notifications, alerts, basic apps Audiobooks, virtual assistants, premium content Podcast narration, extended speeches Real-time virtual assistants, personalized podcasts

Strategies to Optimize Amazon Polly Costs

1. Implement Serverless Batch Processing

AWS Serverless Batch Processing

To efficiently convert large amounts of text into speech using Amazon Polly while minimizing costs, a fully serverless, event-driven solution is implemented using AWS Lambda, Amazon S3, Amazon DynamoDB, and AWS Step Functions. Users upload a YAML-formatted set file containing text phrases to an S3 bucket, which triggers the process. The Set Processor Lambda function parses the file and queues synthesis tasks in Amazon SQS, which are then processed by the Item Processor function, submitting requests to Amazon Polly asynchronously. Once synthesis is complete, the Response Processor function renames and stores the generated audio files in S3 while updating task status in DynamoDB. AWS Step Functions orchestrate the workflow, monitoring progress and sending notifications via Amazon SNS upon completion.

This strategy ensures parallel processing, scalability, and cost efficiency by leveraging pay-as-you-go pricing, allowing synthesized audio to be stored and replayed without additional charges.

Cost Comparison: Serverless vs. Non-Serverless Approach for Text-to-Speech with Amazon Polly

Non-Serverless Approach (EC2, Polly, S3, DynamoDB)

  • EC2 Instance (m5.large): In a non-serverless setup, you'd need to provision EC2 instances to process the workloads. For an m5.large instance running 24/7 for the month, the cost is around $69.12. You’re paying for the uptime of the instance regardless of whether it’s actively processing data or not, which can lead to inefficiencies and higher costs.
  • Amazon Polly: The cost of using Amazon Polly for the same workload is still $1.92, as the pricing for Polly is not affected by the underlying infrastructure.
  • S3 Storage: As in the serverless approach, the cost of storing audio files on S3 is $0.023.
  • DynamoDB: The cost for DynamoDB usage is $0.375, similar to the serverless model, since it’s based on storage and request usage.
  • Miscellaneous (ELB, Data Transfer, Security): In a non-serverless setup, you'll also incur costs for services like Elastic Load Balancer (ELB), data transfer, and security measures such as firewalls, which may add an additional $10.00 for the month.
  • Total Non-Serverless Cost: $81.44 per month.

With a non-serverless model, you’re paying for always-on infrastructure, even when it's idle. This model typically results in higher fixed cost.

Summary

Component Serverless Non-Serverless
Lambda/Compute $0.02 N/A
Amazon Polly $1.92 $1.92
S3 Storage $0.023 $0.023
DynamoDB $0.375 $0.375
Step Functions $2.50 N/A
SNS $0.025 N/A
EC2 N/A $69.12
Miscellaneous Costs N/A $10.00
Total $4.72 $81.44

By using a serverless approach, you can save approximately 94.4% in costs compared to a non-serverless solution. This substantial savings is primarily due to the pay-as-you-go nature of serverless computing, which avoids the need for provisioning and maintaining always-on infrastructure like EC2 instances.

2. Pre-generate and Cache Speech Files

Instead of synthesizing speech in real time, pre-generating the required speech files and storing them in an Amazon S3 bucket for reuse is a more efficient approach. This eliminates redundant synthesis requests and allows unlimited playback at no additional cost. The implementation involves identifying frequently used phrases or sentences, converting them into speech files using Amazon Polly, and storing the audio files in Amazon S3 for direct access.

 This method is particularly useful for applications such as public announcement systems in airports and bus stations, pre-recorded responses for customer service bots, and interactive media like video games.

3. Optimize Voice and Engine Selection

Amazon Polly offers Standard and Neural voices, with neural voices being more expensive. Selecting the appropriate engine based on the use case helps reduce costs. To optimize spending, Standard Voices should be used for applications where high-quality neural voices are unnecessary, while Neural Voices should be reserved for premium applications requiring a more natural tone. Additionally, testing multiple voices allows users to find the best balance between cost and quality for their specific needs.

Comparison Table:

Feature Standard Voices Neural Voices
Cost More affordable More expensive
Use Case Basic applications, notifications Premium applications, virtual assistants, audiobooks
Example Use Case A mobile app sending simple notifications or a text-to-speech alert system for weather updates An AI-powered virtual assistant offering lifelike responses or a premium audiobook narration
Quality Clear and understandable, but less natural More realistic, human-like tone with emotional depth
Best For Simpler tasks where high quality isn’t necessary Applications needing high-quality, lifelike speech
Customization Limited customization options Supports voice customization (e.g., pitch, speaking rate)
Languages and Accents Fewer languages and accents available Supports more languages and regional accents, offering greater localization
Speed of Processing Faster processing, suitable for real-time use cases May have slightly slower processing due to the complexity of neural models

By adding these extra factors, we help paint a fuller picture of when and why you'd choose Standard versus Neural voices depending on the needs of your application, your budget, and your audience. This gives users more context to make informed decisions about Amazon Polly's voice options.

4. Utilize SSML for Dynamic Speech Modification

The Speech Synthesis Markup Language (SSML) is a markup language specifically designed to control how text is converted into speech. It provides a range of features to dynamically modify the speech output without needing to create new audio files or make additional API calls. By using SSML, you can control the prosody (such as pitch, rate, and volume) and speech emphasis, allowing for a more natural-sounding speech experience with dynamic adjustments. SSML helps reduce costs by enabling real-time changes to speech characteristics within the same audio file. For example, if you want a phrase to be spoken slowly or with emphasis, you can insert SSML tags like <prosody rate="slow"> or <emphasis> around specific text.

Without SSML, you might need to generate separate audio files for every variation of speech (e.g., one file for the standard voice and another with slower speech). By using SSML, you can alter these properties dynamically, leading to fewer API calls and lower usage charges. Additionally, SSML streamlines workflows by reducing the need to regenerate audio for every minor tweak, cutting down on storage costs (fewer audio files to store) and preventing additional compute costs associated with unnecessary audio generation.

5. Use AWS Free Tier 

The AWS Free Tier is a promotional offering that allows users to access a limited amount of AWS resources for free, either every month or for a certain duration (typically the first 12 months). Amazon Polly, part of AWS, offers free usage under the AWS Free Tier for Standard TTS voices. This is an excellent option for smaller projects, testing, or low-volume workloads.

Amazon Polly is used by companies like FICO, GE Appliances, Best Western, Twilio, Vonage, and National Australia Bank for lifelike speech in customer service, banking, and healthcare. Other users include Credit Saison, PolicyBazaar, Inhealthcare, and Pillo Health.

Conclusion

Amazon Polly offers powerful TTS capabilities for various applications, but understanding its pricing model and optimizing costs is crucial for maximizing efficiency. By implementing serverless processing, pre-generating speech files, selecting the right voice engine, using SSML, and leveraging AWS Free Tier, businesses can significantly reduce expenses while delivering high-quality speech synthesis solutions.

References

1. Amazon Polly Pricing

2. Optimize your budget and time by submitting Amazon Polly voice synthesis tasks in bulk

3. AI Voice Generator and Text-to-Speech Tool - Amazon Polly

4. Amazon Polly Customers

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