How does this Retell vs Vapi vs Hermes cost calculator work?

It compares the honest monthly cost of three ways to run an AI voice agency: a stack built on Retell, a stack built on Vapi, or the all-in Hermes platform. You enter your total voice minutes a month, how many clients you serve, whether you need white-label, and the dev hours and hourly rate you spend keeping the stack glued together. The tool multiplies your minutes by each engine's true blended rate, then adds the tools every engine path still needs bolted on around it: a CRM, an automation layer, telephony overhead, and the developer time. Against that it computes the Hermes plan that covers your workspaces and minutes, including any overage at $0.24 a minute, and shows the monthly and annual difference. Nothing is stored, every field has a sensible default, and your inputs live in the shareable link so you can send it to a partner and they see the same numbers.

What is the real difference between Retell and Vapi pricing?

Both Retell and Vapi are engines, not platforms, and both advertise a low per-minute headline that is only part of the bill. Retell and Vapi charge a platform fee per minute, then you pay separately for the LLM, the text-to-speech and speech-to-text, and the telephony minutes on top. Once every provider invoice is counted, a real blended voice cost usually lands somewhere between $0.13 and $0.33 a minute depending on the models and voices you pick. Vapi's platform layer tends to run a touch cheaper than Retell's at the base, which is why the calculator defaults Vapi slightly lower, but the gap between them is small compared to the gap between either engine and a finished platform. The bigger number is never the engine, it is everything you have to assemble around the engine to actually run an agency.

Why is a Retell or Vapi stack more expensive than it looks?

An engine gives you minutes and an API. It does not give you a CRM, a campaign dialer, client billing, a white-label portal, or the automation that ties a call outcome to a follow-up. So agencies bolt on GoHighLevel for CRM, Zapier for automation, Stripe for billing, Twilio for telephony, and a developer to keep the seams from splitting. The calculator models the common versions of those line items, roughly $297 a month for an agency CRM tier, $69 for automation, $25 for number and A2P overhead, and your dev hours at your rate, because that recurring maintenance is the cost most operators forget. On a modest book of clients the tooling and dev time around the engine often costs more than the voice minutes themselves. That is the number that quietly eats an agency's margin, and it is exactly what this tool surfaces.

How does Hermes come out cheaper if the per-minute rate is similar?

Hermes is not competing on the per-minute rate, it is replacing the five to seven tools you would otherwise stack on top of Retell or Vapi. A Hermes plan already includes the CRM, campaign orchestration, client billing, and white-label portal, so the $297 CRM, the $69 automation, and most of the developer glue simply disappear from the bill. You pay one plan price, $149 a month for Starter with 300 included minutes, $399 for Business with 1,000, or $699 for Agency with 2,000, plus $0.24 for any overage minute. When the calculator adds the real tooling and dev cost to the engine path, Hermes usually lands lower even before you count the hours you get back. The savings come from collapsing the stack, not from shaving a fraction of a cent off each minute.

How accurate are the default rates in the calculator?

The defaults are deliberately conservative so the comparison stays honest rather than flattering. Engine minutes are modeled at a blended all-in rate that includes the LLM, voice, and telephony, not just the platform headline, and you can steer the total by entering your real minute volume. The CRM, automation, and telephony line items reflect common agency-tier pricing for GoHighLevel, Zapier, and Twilio number overhead, and the dev cost is driven entirely by the hours and rate you enter, so if you maintain the stack yourself at zero cash cost you can set the rate to your own hourly value. If your real numbers differ, put them in and the output moves with them. The point is not a perfect quote, it is a defensible side-by-side you can pressure-test against your own invoices.

How do I move my agency from Retell or Vapi to Hermes?

Most operators do not rip everything out on day one, they move one client and compare. Hermes is the operating platform underneath the agency: you deploy and manage voice agents under your own brand, with CRM, campaign orchestration, and transparent billing in one place, so your client never sees Hermes and you stop reconciling five invoices by hand. The first agent is typically live within 72 hours, and the workspaces map to your clients, so the plan grows as your book does. Book a 20-minute walkthrough and we will take the exact minutes, client count, and stack you entered here, map them to the right plan, and show your real all-in cost against what you pay today. Bring an invoice or two and we will pressure-test the numbers together.

free tool

Retell vs Vapi vs Hermes: what does your stack really cost?

The per-minute rate is never the whole bill. Plug in your minutes, clients, and the tools you bolt on around the engine to see the true monthly cost of a Retell or Vapi stack against Hermes all-in, plus your annual savings.

/ total voice minutes per monthAll client calls combined, inbound plus outbound, across your whole book./ number of clientsEach client needs its own branded workspace under your agency./ white-label requiredOn the engine path, white-label means SaaS-mode CRM or custom portals./ dev hours per month on the stackTime you or a contractor spend keeping the glue between tools intact./ dev hourly rate (USD)What that hour costs, whether it is a contractor or your own time.

/ monthly cost, all in

Retell stack

$1,511

engine + CRM + automation + telephony + dev

Vapi stack

$1,451

engine + CRM + automation + telephony + dev

Hermes, all in

$639 · Business

Business plan (1,000 included minutes) plus $0.24 per overage minute. White-label, CRM, campaigns, and billing built in.

You save vs the cheaper engine path (Vapi)

$812/mo

$9,744 a year back in your pocket.

Book a 20-min walkthrough to cut this number, and we will map your minutes, clients, and stack to a plan and show your real all-in cost. Want the full breakdown for your agency? Book 20 min.

Book a 20-min walkthrough

how it works

The engine is the cheap part. The stack around it is not.

Retell and Vapi are engines, not platforms. They hand you minutes and an API, and both advertise a low headline rate that hides the LLM, the voice synthesis, and the telephony you pay for on top. Counted honestly, a blended voice minute usually lands between $0.13 and $0.33. That gap between Retell and Vapi is real, but it is small next to the gap between either engine and a finished agency platform, because the engine was never the expensive part.

The expensive part is everything you assemble around it. An engine does not give you a CRM, a campaign dialer, client billing, or a white-label portal, so agencies bolt on GoHighLevel, Zapier, Stripe, and Twilio, then pay a developer to keep the seams from splitting. This calculator models the common versions of those line items and adds the dev hours you enter at your own rate. On a modest book of clients, the tooling and maintenance around the engine routinely cost more than the voice minutes themselves. That is the number that quietly eats your margin.

Hermes does not win by shaving a fraction of a cent off each minute. It wins by collapsing the stack. The CRM, campaign orchestration, client billing, and white-label portal are already in the plan, so the $297 CRM, the $69 automation, and most of the developer glue disappear from the bill. You pay one price, $149 a month for Starter, $399 for Business, or $699 for Agency, plus $0.24 for any overage minute, with the whole book of clients under your own brand. Enter your real numbers above and see where the line lands.

frequently asked

Common questions.

next step

Run your agency on Hermes.

One platform. Your brand. From $149/month. First agent live in 72 hours.

Book a 20-min walkthrough See pricing

Retell vs Vapi vs Hermes: what does your stack really cost?

The engine is the cheap part. The stack around it is not.

Common questions.

Run your agency on Hermes.

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