High-volume TTS API: EasyVoice $9.99 flat up to 10M characters a month
At high text-to-speech volumes — millions of characters per month — the difference between per-character and flat-rate pricing is not a rounding error. It is the difference between a TTS bill that fits in a rounding line on your engineering budget and one that becomes a dedicated finance-team conversation. EasyVoice Pro costs $9.99 per month up to its fair-use guideline of 10,000,000 characters per rolling 30 days. OpenAI's tts-1 costs $15 per million characters; tts-1-hd costs $30 per million (OpenAI list prices checked September 2026). The two cost the same at about 666K characters a month on tts-1; below that, tts-1 can cost less, and above it the flat rate does. At 5 million characters per month, tts-1 costs $75/mo versus EasyVoice's $9.99. At 10 million characters per month, tts-1 costs $150/mo versus EasyVoice's unchanged $9.99. This page shows the cost math at 1M, 5M and 10M characters per month, the breakeven thresholds, what happens above the fair-use line, and when OpenAI's per-character billing is actually the right call.
5,000 characters per day free, no credit card. Pro $9.99/mo unlimited (fair use 10M characters per 30 days).
What does EasyVoice cost at enterprise scale?
At 5 million characters per month — a realistic volume for a customer-service platform handling about 833 interactions a day of 200 characters each — OpenAI tts-1 costs $75/month and tts-1-hd costs $150/month (list prices checked September 2026). EasyVoice Pro costs $9.99/month. The annual saving versus tts-1-hd alone is $1,680.12. At 10 million characters per month, OpenAI tts-1 costs $150/month versus EasyVoice's unchanged $9.99/month.
The cost math at three volumes: at 1 million characters per month, OpenAI tts-1 charges $15/mo, tts-1-hd charges $30/mo, EasyVoice charges $9.99/mo. At 5 million characters per month, OpenAI tts-1 charges $75/mo, tts-1-hd charges $150/mo, EasyVoice charges $9.99/mo. At 10 million characters per month, OpenAI tts-1 charges $150/mo, tts-1-hd charges $300/mo, EasyVoice charges $9.99/mo. Fair use: 10,000,000 characters per rolling 30 days; beyond that the account is slowed, never blocked or billed. Sustained volume above that line needs a separate written agreement — use the Send feedback button at easyvoice.ae.
The breakeven thresholds — 666K and 333K chars/mo
There are exactly two volume thresholds where the vendors cost the same (OpenAI list prices checked September 2026). Against OpenAI tts-1: 9.99 / 15 × 1,000,000 = 666,000 characters per month. Above 666K chars/mo, EasyVoice is cheaper. Against OpenAI tts-1-hd: 9.99 / 30 × 1,000,000 = 333,000 characters per month. Above 333K chars/mo, EasyVoice is cheaper. These are arithmetic facts, not estimates.
For high-volume applications, both breakevens are reached quickly. A customer support chatbot handling 1,500 conversations per day at 200 characters per bot response generates 1,500 × 200 × 30 = 9 million characters per month — about 13.5× the tts-1 breakeven and 27× the tts-1-hd breakeven, and still inside Pro's 10M fair use. The EasyVoice saving at that volume against tts-1 is $125.01/mo ($135 OpenAI vs $9.99 EasyVoice); against tts-1-hd it is $260.01/mo.
The OPENAI_PRICING_ROWS pricing table (imported from the shared pricing const) shows the cost comparison at 100K, 333K (tts-1-hd breakeven), 500K, 666K (tts-1 breakeven), 1M, 5M, and 10M characters per month. All rows use OpenAI list prices checked September 2026: tts-1 $15/1M, tts-1-hd $30/1M, EasyVoice Pro $9.99 flat.
Real enterprise-volume use cases and their bills
IVR and contact center: a contact center handling 3,000 calls per day, with about 100 characters of TTS-generated hold messages and menu prompts per call, generates 3,000 × 100 × 30 = 9 million characters per month. OpenAI tts-1: $135/mo. OpenAI tts-1-hd: $270/mo. EasyVoice Pro: $9.99/mo.
Content audio versions: a publisher generating MP3 audio versions of 25 articles per day, each approximately 2,000 words (≈12,000 characters), generates 25 × 12,000 × 30 = 9 million characters per month. OpenAI tts-1: $135/mo. OpenAI tts-1-hd: $270/mo. EasyVoice Pro: $9.99/mo. A newsroom voicing hundreds of articles a day (for example 500 × 12,000 × 30 = 180 million characters a month) is far beyond Pro's fair use and needs a separate written agreement — contact us through the Send feedback button at easyvoice.ae.
E-commerce product catalog: an e-commerce platform with 50,000 products generating audio descriptions of 200 characters each, re-synthesized monthly for freshness, generates 50,000 × 200 = 10 million characters per batch. Monthly cost on OpenAI tts-1: $150. Monthly cost on EasyVoice Pro: $9.99. Annual difference: $1,680.12.
Why does flat-rate work at this scale?
EasyVoice's flat-rate model works at high volume because the underlying TTS engine — Kokoro-82M — is a small model: 82 million parameters, much smaller than frontier AI models, and it runs efficiently on commodity GPU infrastructure. The marginal cost of a generated character at Kokoro's inference efficiency is low enough that a flat $9.99/mo plan with a fair-use guideline is sustainable. OpenAI does not publish the size of its TTS models; its per-character pricing is a metered business model.
The trade-off is real: Kokoro-82M is not GPT-4o-audio. For the dominant TTS use cases — customer service scripts, IVR prompts, content narration, accessibility read-aloud, chatbot responses — we have no blind-test record, so listen to the voices before you commit. For specialized use cases where voice nuance is the primary deliverable (premium audiobooks, close-mic'd character voice acting), tts-1-hd's quality premium may be worth $150/mo at 5M chars.
Is there a per-character surcharge at high volume?
No. EasyVoice Pro is a flat $9.99 per month with no per-character surcharge, no volume tier, and no overage charges, ever. The $9.99 you pay at 1 million characters per month is the same $9.99 you pay at 10 million characters per month. Fair use: 10,000,000 characters per rolling 30 days; beyond that the account is slowed, never blocked or billed. Sustained volume above the line — or building a voice service for other people — needs a separate written agreement; use the Send feedback button at easyvoice.ae.
This is worth stating explicitly because most API pricing — including OpenAI's — works the opposite way: higher volume means a higher bill. EasyVoice's model inverts this up to the fair-use line: the bill stays flat as volume grows. For finance teams modeling TTS cost as a function of user growth, EasyVoice's line item is a constant up to 10M characters a month; OpenAI's is a variable proportional to product success.
When should high-volume users stay on OpenAI?
Switch to EasyVoice if your monthly volume exceeds approximately 666,000 characters per month (the tts-1 breakeven) or 333,000 characters per month (the tts-1-hd breakeven). At these thresholds and above, EasyVoice's $9.99 flat costs less than OpenAI's per-character billing at the list prices checked September 2026, and the gap widens as volume grows.
Stay on OpenAI if you stay under a few hundred thousand characters per month and want pay-as-you-go billing with no monthly commitment — below the breakeven, OpenAI's per-character rate is genuinely cheaper than $9.99 flat. Also stay on OpenAI if tts-1-hd's fidelity is a hard requirement for your specific use case (close-mic'd character voice acting, premium audiobook production) and your monthly volume is moderate enough that the cost is acceptable.
Pricing at common monthly volumes
Real arithmetic, not estimates. Verified against OpenAI's official pricing ($15/1M chars on tts-1, $30/1M on tts-1-hd) as of 2026-09-27. Negative savings values mean OpenAI is cheaper at that volume (below breakeven).
| Volume | OpenAI tts-1 | OpenAI tts-1-hd | EasyVoice Pro | Savings vs tts-1 /mo | Annual savings vs tts-1-hd |
|---|---|---|---|---|---|
| 100K chars/mo | $1.50 | $3.00 | $9.99 | -$8.49 | -$83.88 |
| 333K chars/mo (tts-1-hd breakeven) | $5.00 | $9.99 | $9.99 | -$4.99 | $0.00 |
| 500K chars/mo | $7.50 | $15.00 | $9.99 | -$2.49 | $60.12 |
| 666K chars/mo (tts-1 breakeven) | $9.99 | $19.98 | $9.99 | $0.00 | $119.88 |
| 1M chars/mo | $15.00 | $30.00 | $9.99 | $5.01 | $240.12 |
| 5M chars/mo | $75.00 | $150.00 | $9.99 | $65.01 | $1680.12 |
| 10M chars/mo | $150.00 | $300.00 | $9.99 | $140.01 | $3480.12 |
Breakeven points: 666K chars/mo (vs tts-1), 333K chars/mo (vs tts-1-hd). Above those volumes, EasyVoice's flat $9.99/mo Pro is cheaper — and the gap widens linearly because the EasyVoice price doesn't change with volume.
Voices to try
Every voice below is callable via the same voice parameter — preview audio samples and read the full character profile.
Frequently asked questions
What does EasyVoice cost at 10 million characters per month?▾
EasyVoice Pro costs $9.99 per month at 10 million characters per month — the same flat rate as at 1 million or 100,000 characters. OpenAI tts-1 costs $150/month at 10M chars/mo, and tts-1-hd costs $300/month (OpenAI list prices checked September 2026). 10 million characters per rolling 30 days is Pro's fair-use guideline: above it the account is slowed — never blocked or billed — and sustained higher volume needs a written agreement.
At what monthly volume does OpenAI tts-1 break even with EasyVoice?▾
666,000 characters per month. The calculation: $9.99 / $15 per million × 1,000,000 = 666,000 chars/mo (OpenAI tts-1 list price checked September 2026). Below 666K chars/mo, OpenAI tts-1 costs less. Above 666K chars/mo, EasyVoice's $9.99 flat costs less — and the saving grows linearly. At 1M chars/mo EasyVoice saves $5.01/mo; at 5M chars/mo it saves $65.01/mo; at 10M chars/mo it saves $140.01/mo.
Is there a per-character surcharge at high volume on EasyVoice?▾
No. EasyVoice Pro is $9.99 per month with no per-character surcharge, no volume tier, and no overage charges. The flat rate covers everything up to Pro's fair-use guideline of 10,000,000 characters per rolling 30 days; above that, API requests are paced and long-form jobs wait behind other customers' jobs, but it is never billed. Finance teams can model EasyVoice TTS cost as a constant line item up to that line.
Does the $9.99 flat rate change at enterprise scale?▾
No. The $9.99 EasyVoice Pro monthly rate does not change based on volume, and there are no overage charges. The same plan that covers 500,000 characters per month covers 10 million characters per month at the same price. Above 10 million characters per rolling 30 days, fair use applies: the account is slowed (never blocked or billed), and sustained volume at that level — or reselling capacity to others — needs a separate written agreement (use the Send feedback button at easyvoice.ae).
What is the annual saving on OpenAI tts-1-hd at 5M chars/mo?▾
At 5 million characters per month, OpenAI tts-1-hd costs $150/month ($1,800/year) and EasyVoice Pro costs $9.99/month ($119.88/year). The annual saving is $1,680.12. The monthly saving of $140.01 means an assumed $300-$600 of engineering time (at $150/hr fully-loaded, for the change plus validating it on your own test cases) is recovered in 2-4 months.
Related OpenAI migration guides
OpenAI TTS pricing vs EasyVoice — when flat-rate wins
OpenAI TTS costs $15 per 1M characters on tts-1 and $30 on tts-1-hd, with no free tier. Monthly cost at 100K to 10M characters and the $9.99 flat breakeven.
OpenAI TTS has no free tier — EasyVoice gives you 5,000 chars/day, permanently
OpenAI TTS has no free tier. EasyVoice offers 5,000 characters/day free — no credit card, no 30-day trial, permanent daily reset at UTC midnight. Start free.
OpenAI TTS commercial use vs EasyVoice — Apache-2.0 license, AudioSeal watermark, consent gate
OpenAI TTS commercial use vs EasyVoice: Kokoro-82M is Apache-2.0, every plan allows commercial use, and cloning needs consent plus an AudioSeal watermark.
Vendor comparison: EasyVoice vs OpenAI TTS
Side-by-side feature comparison covering voices, languages, pricing tiers, free limits, API surface, and the why-people-look / where-each-wins breakdown.
API reference: /audio/speech, Jobs API and limits
Every request parameter, rate limit and error code, the Jobs API for long text, and copy-paste examples using the official openai SDK with the EasyVoice base URL.
Start migrating off OpenAI TTS today
5,000 characters per day free, no credit card. Pro $9.99/mo unlimited replaces per-character bills once they grow past the breakeven shown on the pricing page.