Cal.ai vs Retell AI

Two fact sheets from our own research, side by side — pricing, platforms, API access and status re-checked by us rather than quoted from the vendors.

The short answer

Cheaper paid plan: Retell AI — $0.07/min vs $0.29/min for Cal.ai
Free plan: Only Retell AI (Cal.ai has paid plans only)
Public API: Both have one
Best fit: Cal.ai: Sales teams doing outbound meeting booking by phone · Retell AI: Teams replacing an outbound qualification or booking script
Trust score: About even — Cal.ai 92, Retell AI 92

From our own records as of each tool's last check. Anything we have not confirmed is left out rather than guessed. How we verify

Cal.aiAI phone agents from Cal.com that call to book, confirm, and follow up on meetings.

Retell AIBuild and run AI phone agents that book, qualify and transfer calls, billed by the minute.

Side by side

Fact	Cal.ai	Retell AI
Category	Meeting Scheduling	Voice Agents & Phone AI
Pricing model	Paid	Freemium
Starts at	$0.29/min	$0.07/min
Public API	Yes	Yes
Trust score	92 / 100	92 / 100
Platforms	Web, API	Web, API
Company	Cal.com, Inc.	Retell AI Inc.
Launched	—	2023
Last verified	Oct 15, 2026	Oct 15, 2026

What our research says

Cal.ai

Cal.ai replaces a human caller with an AI voice agent that actually dials out or answers to get a meeting on the calendar, a step beyond typical link-based scheduling tools. Because it bills per minute on top of a Cal.com plan, costs scale directly with call volume, and it makes most sense for teams already running calendar operations through Cal.com.

Pros

Handles outbound and inbound calls to book, confirm, and follow up on meetings
Integrates directly with existing Cal.com calendar workflows
Team and organization plans include a monthly credit allowance

Cons

Per-minute billing means costs are unpredictable at high call volume
Requires an underlying Cal.com subscription, so it's not a stand-alone tool
No free allotment beyond bundled plan credits

Retell AI

One of the more honest voice-agent stacks: the pricing page breaks out infrastructure, TTS and LLM cost per minute so you can predict a call's cost instead of guessing. Telephony choice is wide and the concurrency allowance is generous. The catch is that per-minute billing plus add-ons makes a busy contact centre expensive fast, and the cheap end of the range only holds if you pick the cheap models.

Pros

Per-minute cost broken down by voice infrastructure, TTS provider and LLM on the public pricing page
Telephony via SIP trunking, Twilio and Vonage plus n8n, HubSpot, Make and Go High Level integrations
20 concurrent calls included before any concurrency charge
Voice, chat and SMS agents share one platform and API
HIPAA path exists via a signed BAA covered in the terms of service

Cons

Cost per minute more than quadruples between the cheapest and most capable model combinations
Knowledge base, denoising, PII removal and branded caller ID are all metered extras
No flat-rate plan, so a spike in call volume lands straight on the invoice

Which one fits

Choose Cal.ai if you need

Sales teams doing outbound meeting booking by phone
Healthcare or service front desks confirming appointments
Teams already on Cal.com wanting to add voice

Choose Retell AI if you need

Teams replacing an outbound qualification or booking script
Contact centres that already have Twilio, Vonage or SIP trunking
Developers who want per-minute cost visibility before launch