Retell AI vs Vapi for a phone agent
Retell AI and Vapi both sell the parts of a voice agent by the minute, and both expect you or a developer to build it. Retell quotes an all-in range of $0.07 to $0.31 a minute and includes 20 concurrent calls. Vapi charges $0.05 a minute in hosting, then passes transcription, model and voice through at cost.
The pricing shape is the real difference. Retell's rate card itemizes its own layers, voice infrastructure at $0.055 a minute and US telephony at $0.015. Vapi keeps its fee to hosting and lets you pick every provider underneath, which makes the model you choose the biggest line on the bill.
Retell suits a builder who wants a published per-minute range and headroom on concurrent calls from day one. Vapi suits a builder who wants to choose each provider and pay for support in packages. Both pricing pages were read on 24 September 2026.
Published pricing, side by side
What each vendor prints on its own site. The billing unit decides more of the final bill than the headline price does.
| Retell AI | Vapi | |
|---|---|---|
| Billing unit | Per minute, plus monthly add-ons | Per minute, plus provider costs |
| Entry plan | Pay as you go at $0.07–$0.31 a minute, with $10 in free credits | $0.05 a minute hosting, with transcription, model and voice passed through at cost; $5 in free credit to start |
| Higher tiers | Pay as you go or Enterprise; voice infra $0.055/min, platform voices $0.015/min, US telephony $0.015/min, numbers $2.00/month | Core $29/mo (10 calls at once, 5 Vapi numbers); Pro at 10% of hosting with a $999/mo minimum (30 calls at once, 10 numbers); Premier custom |
| Overage rate | Every minute is metered; concurrency past the 20 free calls is $8.00 each a month | Every minute is metered; Vapi's own calculator puts 1,000 minutes at $82–$129 a month |
Read on each vendor's own website in September 2026. Prices move, so check before you buy.
What decides it
The dimensions that change the bill or the service, each as a fact read on the vendor's own site.
| Retell AI | Vapi | |
|---|---|---|
| Free credit to start | $10 | $5 |
| Platform fee per minute | Voice infra $0.055, platform voices $0.015 | Hosting $0.05 |
| Model, voice and transcription | Inside the $0.07–$0.31 range, by the parts you pick | Passed through at provider cost |
| Calls at once | 20 free, then $8.00 each a month | 4 with no package; 10 on Core ($29); 30 on Pro |
| Phone numbers | $2.00 a month each | 1 with no package; 5 on Core; 10 on Pro |
| Paid packages | Pay as you go, or Enterprise | Core $29 a month; Pro at 10% of hosting, $999 minimum; Premier custom |
Retell AI: retellai.com/pricing. Vapi: vapi.ai/pricing and its calculator. Both read September 2026.
Concurrency matters more for a receptionist than for a demo
A receptionist line gets bursts. Monday at nine, three people ring at once. A voice agent that can take only a few calls together sends the rest to busy or voicemail.
Retell includes 20 concurrent calls before it charges $8.00 a month for each extra line. Vapi's no-package start allows four at once. Core, at $29 a month, raises that to ten, and Pro raises it to 30.
So a small office testing on Vapi's free start can hit the ceiling on its first busy morning. Price the package you'd run in production, not the one you'd test on.
How each bill is put together
Retell publishes a range of $0.07 to $0.31 a minute for its voice agents. Where you land depends on the model and voice you pick. Numbers cost $2.00 a month each, and you start with $10 in free credits.
Vapi splits the bill into its hosting fee and everything else. Hosting is $0.05 a minute. Transcription, the language model and the voice are billed at the provider's price, and Vapi's own calculator estimates 1,000 minutes at $82 to $129 a month.
Either way, your average call length multiplies the whole bill. A three-minute receptionist call costs three times what a one-minute call does on both platforms.
The work that sits on top of the minutes
Neither platform arrives as a receptionist. You write the prompt that greets callers, the rules for who gets transferred, and the calendar connection that books a slot. Then you test it against real callers and keep it current when your hours change.
If you're a developer building a phone product, that's the job you signed up for, and both platforms give you the pieces. If you're a business owner who wanted the phone answered, count those hours in the cost before you compare per-minute rates.
If you want the receptionist, not the build
Disclosure: GreetKeeper is our product, and this is its only mention on the page. It's a finished AI receptionist sold per answered call. Starter is $49 a month for 200 calls, Professional $149 for 750 and Scale $349 for 2,000, with $0.45, $0.35 or $0.25 for each call past the plan.
There's no prompt to write. Point GreetKeeper at your website for a first draft of your hours, services and FAQs, then correct it. Booking into Google Calendar or Outlook, transfers to your team and a transcript with a short summary come on every plan, and calls that arrive together are answered at the same time.
Developers still get a hook: a signed JSON webhook for call.completed, booking.created, message.taken and transfer.made, retried on failure. Every plan starts with a 14-day free trial, every feature on and no card.
| Plan | Monthly | Calls included | After that |
|---|---|---|---|
| StarterFor a single location taking calls one line at a time. | $49 | 200 | $0.45 per call |
| ProfessionalBooking, routing and transfers included, not an add-on. | $149 | 750 | $0.35 per call |
| ScaleFor busy phones and longer opening hours. | $349 | 2,000 | $0.25 per call |
Questions people ask about this comparison
Is Retell AI or Vapi cheaper?
Neither has one price, because both bill by the minute and the model and voice you pick set the rate. Retell's all-in range is $0.07 to $0.31 a minute. Vapi's calculator estimates 1,000 minutes at $82 to $129 a month, including its $0.05 hosting fee (September 2026).
How many calls can Retell AI and Vapi take at once?
Retell AI includes 20 concurrent calls, then charges $8.00 a month for each extra. Vapi allows four with no package, ten on its $29 Core package and 30 on Pro, read September 2026.
Does Vapi charge for phone numbers?
Vapi includes one Vapi number with no package, five on Core and ten on Pro. Retell AI charges $2.00 a month per number. Both figures were read on the vendors' pricing pages in September 2026.
Do I need a developer for Retell AI or Vapi?
In practice, yes. Both are platforms for building a voice agent, so the greeting, transfer rules and calendar booking are yours to set up and maintain. If you don't write code, budget for someone who does.
Skip the build this week
Point GreetKeeper at your website, correct the draft and call your own number.