Pay-per-message pricing charges for every message your automation sends, so the bill follows your volume message by message. Per-contact pricing charges by how many people you talk to. Flat pricing charges the same each month and caps usage with quotas instead. For a quiet account, paying per message can cost less than any monthly plan. Once a post brings in hundreds of comments and each one gets a reply and a DM, the message count grows faster than the number of people, and that is where the three models drift apart.
How per-contact and flat plans behave when a post goes viral is covered in flat vs per-contact pricing. This article works through the per-message math.
What each model counts
| Model | What is counted | One person who comments, gets a public reply and a DM |
|---|---|---|
| Per message | every message sent | 2 messages |
| Per contact | every person you talk to | 1 contact |
| Flat with quotas (VivaDialog) | conversations with an automatic reply, and AI replies | 1 conversation |
In VivaDialog a conversation is one comment thread or one DM thread, counted once a month when the first automatic reply goes out to it. A DM sent for a comment counts as the same conversation as the comment. Each AI reply also counts toward a separate AI reply quota. Replies your team writes by hand are never counted. What counts as a conversation has the full rules.
The numbers used below
VivaDialog’s prices and quotas come from the pricing page:
| Plan | Monthly | Billed yearly, per month | Conversations a month | AI replies a month |
|---|---|---|---|---|
| Starter | $9 | $7.20 | 500 | 200 |
| Growth | $12 | $9.60 | 2,000 | 1,000 |
| Pro | $20 | $16 | 10,000 | 3,000 |
| Premium | $35 | $28 | 50,000 | 8,000 |
For the per-message side we use a made-up rate of $0.01 per message. It is a round number for the arithmetic, not any real tool’s price. Swap in the rate from the pricing page of the tool you are comparing and the method stays the same.
Example 1: a keyword post
A bakery posts “Comment PRICE for the cake menu”. 1,000 people comment it. The automation posts a short public reply and sends each person the menu by DM.
- Messages sent: 1,000 public replies + 1,000 DMs = 2,000.
- Per message at $0.01: $20.
- Per contact: 1,000 contacts, so the plan tier that includes at least 1,000 contacts.
- VivaDialog: 1,000 conversations and no AI replies. Starter’s 500 conversations would run out halfway; Growth’s 2,000 covers it for $12 a month.
Example 2: the same post, with DM follow-ups
Of those 1,000 people, 300 answer the DM with a question, and an automation answers each of them twice with AI.
- Messages sent: 2,000 from example 1 + 600 AI answers = 2,600.
- Per message at $0.01: $26. Every extra exchange in a DM adds to the bill.
- Per contact: still 1,000 contacts, since nobody new joined.
- VivaDialog: each of the 300 DM threads is a conversation of its own, so 1,300 conversations, plus 600 AI replies. Both fit in Growth (2,000 and 1,000), and the bill stays $12.
In a per-message model a long back-and-forth costs more with every reply. VivaDialog counts a thread once a month, however many automatic replies go out in it. AI replies are the exception, since each one counts toward the AI reply quota.
Example 3: a quiet month
A small account gets 40 questions in the comments and answers each with one public reply.
- Messages sent: 40.
- Per message at $0.01: $0.40.
- VivaDialog: 40 conversations, well inside Starter at $9.
Here paying per message costs less. At the made-up rate, the per-message bill only reaches Starter’s $9 at 900 messages a month, and Growth’s $12 at 1,200. If your volume stays low and steady, a per-message tool can be the cheaper choice for you.
When the volume passes the plan
A per-message bill has no ceiling: a month with 12,000 automatic messages costs 12,000 times the rate. A flat plan keeps the price and stops part of the automation instead. In VivaDialog:
- when the conversation quota is used up, automations and AI stop answering new conversations until the 1st of the next month (UTC); conversations already counted that month keep getting automatic replies;
- when the AI reply quota is used up, AI replies stop, and automations with fixed text keep working;
- replies you write in the inbox always go out, and incoming comments and DMs keep arriving.
The workspace owner gets an email at 80% and at 100% of a quota. Add-on packs for a busy month are listed on the pricing page but are not on sale yet, so for now a bigger month means a bigger plan or waiting for the reset.
Questions to ask any pricing page
- Does a public reply count as a message, and does a DM sent for a comment count separately?
- Are replies you type yourself charged or counted?
- Are AI replies included, or charged as extra messages or credits?
- What happens at the limit: a higher bill, an upgrade, or a pause?
How VivaDialog pricing works answers these for VivaDialog in one place. VivaDialog is in early access right now, and participants get the Growth plan free for 30 days. The pricing page has the details.