If your customers are in Brazil, India or most of Europe, the WhatsApp vs SMS question mostly answers itself, because WhatsApp is how people talk there. In the US the picture is different. Almost every phone can receive a text with no app, no account and no setup. WhatsApp only reaches the people who installed it and actually open it, which in the US is a smaller and more specific group than the global numbers suggest.
This post compares the two channels for a US audience on reach, opt-in rules, cost and compliance. It also covers where WhatsApp is the better choice. We make Ready, an SMS platform, so we have a side in this. We've tried to be specific enough that you can check the reasoning yourself.
Reach: installed base vs every phone
SMS is built into the phone. A US mobile number can receive a text whether it belongs to an iPhone, an Android, or a flip phone that a contractor keeps in his truck. You don't need to know anything about the recipient beyond the number and the fact that they agreed to hear from you.
WhatsApp reaches people who have the app, are logged in and haven't muted you. Most survey estimates put regular US usage at a minority of adults. It is concentrated among people with family or business ties abroad, frequent international travelers, and some immigrant communities. For those groups WhatsApp can be the main channel. For a general US list it covers only part of your audience.
In practice this means:
- General US consumer list: SMS reaches nearly everyone with a mobile number. WhatsApp reaches whoever on the list happens to use it.
- Diaspora or international audience: WhatsApp may beat SMS on engagement, and texting international numbers from a US 10DLC number isn't what those numbers are for anyway.
- B2B in the US: Mostly SMS and email. Some international trades run on WhatsApp groups.
We cover the list-size side of this in more depth in Bulk SMS vs WhatsApp for US business messaging.
Opt-in rules: both require consent, and they enforce it differently
Neither channel lets you message people who never agreed to hear from you, but the two enforce that in different ways.
Meta requires opt-in before a business starts a conversation. The first message must be a pre-approved template, sorted into a category such as marketing, utility or authentication. Once a customer messages you, a 24-hour customer-service window opens, and inside it you can reply freely. Outside that window you're back to templates.
Meta also tracks a quality rating on your number. If too many people block or report you, your sending limits can drop or your account can be restricted. Meta's policy and Meta's decision are what govern this.
SMS
In the US, SMS marketing falls under the TCPA. Statutory damages run roughly $500 to $1,500 per text, so a sloppy list can cost a lot. On top of the law, carriers require A2P 10DLC registration: your brand and your campaign use case are registered and vetted before traffic flows on a local number. Unregistered traffic gets filtered. If you're new to this, what 10DLC is explains the basics. 10DLC vs toll-free vs long code vs RCS covers which sender type fits which business.
The practical difference: WhatsApp enforces consent mostly through platform rules and account health. SMS enforces it through carrier registration and federal law. SMS carries the higher legal stakes, which is why tooling around it matters.
A note on WhatsApp and the TCPA: don't assume a message is outside the TCPA because it went over an app. Get proper consent on both channels and keep your own records of it.
Cost: different pricing models
WhatsApp and SMS bill differently, so comparing them line by line takes some care.
WhatsApp charges per message or conversation, depending on Meta's current model. The rate varies by message category (marketing costs more than utility) and by the recipient's country code. A marketing template to a US number can cost more or less than an SMS segment. Check Meta's current rate card before you assume either way, because Meta has changed the model more than once.
SMS bills per segment. A segment is 160 GSM-7 characters. Longer messages split into 153-character parts. One emoji drops the limit to 70 characters, or 67 per part in a multipart message. Every segment is billed.
Worked example: a 5,000-contact SMS campaign on Ready
The assumptions here are an opted-in list of 5,000 contacts and Ready's Standard rate of $0.0075/segment plus a $0.0045 carrier fee per segment.
Version A: a 150-character plain-text promo, 1 segment
- 5,000 × 1 = 5,000 segments
- 5,000 × $0.0075 = $38, plus 5,000 × $0.0045 = $22.50 in carrier fees, $60.00 in all
Version B: a 175-character promo with one emoji, 3 unicode segments
- 5,000 × 3 = 15,000 segments
- 15,000 × $0.0075 = $113, plus 15,000 × $0.0045 = $67.50 in carrier fees, $180.00 in all
The emoji tripled the bill. Cut the copy to fit one segment and drop the emoji, and you get the same message at a third of the cost. Ready swaps curly quotes, long dashes and ellipses for plain ones before sending, so pasted copy from a doc won't push you into unicode by accident.
These all-in figures don't include screening. TCPA/DNC scrubbing and landline validation each add $0.003 per segment when switched on for an account, and both are off by default. Replies you receive are billed like a sent text.
There are fixed costs too. 10DLC registration has no setup fee. You pay $25 at submit, which covers the first month. After that, the monthly cost is $25/mo for registration plus $2 per number. Most approvals take 2 to 7 days.
To be clear about price: if all you need is the lowest per-segment cost, raw carrier APIs like Twilio come in lower than our Standard rate. What you get with Ready is everything that sits around the send: registration in the app, compliance tooling, the inbox and automations. For a fuller breakdown, see the SMS marketing pricing buyer's guide.
Side-by-side comparison
| SMS (10DLC) | WhatsApp Business | |
|---|---|---|
| US reach | Nearly every mobile number | Only app users, a minority of US adults |
| Recipient needs | Nothing | App installed and logged in |
| Business-initiated messages | Allowed with consent and registration | Approved templates only |
| Rich media | MMS (picture) | Images, buttons, catalogs, documents |
| Pricing model | Per segment | Per message or conversation, by category and country |
| Main compliance pressure | TCPA plus carrier registration | Meta policy plus quality rating |
| Best fit | US consumer and local audiences | International and diaspora audiences |
Where WhatsApp wins
WhatsApp is the better pick in these cases:
- Your audience is outside the US or uses WhatsApp as its default messenger.
- You need rich interactions, such as catalogs, buttons and long threaded support chats, and your audience already lives in the app.
- Your customers start the conversation, for example through a click-to-WhatsApp ad, so the 24-hour window covers most of your messaging.
If any of those describe your business, run WhatsApp. Many brands run both channels and route each contact to the one they actually reply on.
Where SMS wins
SMS is the better pick in these cases:
- US consumer lists of any size. You aren't limited to people who installed a particular app.
- Time-sensitive messages, such as appointment reminders, shipping updates, flash sales and lead follow-up, where the message has to arrive and be seen without depending on app notifications.
- Local businesses and platforms texting on behalf of many customers. Sub-accounts with their own numbers and registration scale better than separate WhatsApp Business setups for every customer.
- Teams that need compliance controls in the send path. These are covered below.
If you want a richer, branded experience in the US without leaving native messaging, look at iMessage or RCS rather than WhatsApp. Ready's blue line sends as iMessage to iPhones, showing your business name and photo, for $99 a month per line plus 6 cents a segment. Texts to Android phones go as regular SMS from your regular number at its normal rate; if your green number came with the blue line, they bill at 6 cents a segment once you register. RCS vs SMS for marketing covers the Android side.
What the SMS compliance stack looks like on Ready
Compliance is ultimately the sender's responsibility. Good tooling reduces risk but doesn't remove it. Here is what Ready handles:
- Registration in the app. Brand and campaign 10DLC registration is submitted from your dashboard. Most approvals take 2 to 7 days.
- STOP handling. Inbound STOP and UNSUBSCRIBE are honored automatically. The opt-out applies across all your campaigns, and later sends to that number are refused without charge.
- Quiet hours. Sends are held outside permitted local hours based on the recipient's area, and you're charged only when they go out. Campaigns, drip campaigns and automations wait up to 24 hours for the window; a one-to-one or API text is held only if the window opens within 6 hours, otherwise it is refused and must be resent; a one-to-one reply to someone who texted you in the last 24 hours goes out at any hour.
- Litigator and DNC scrubbing. When switched on, this runs at $0.003 per segment. A standalone scrub is $0.005 per contact.
- Attestation records. Ready logs who sent each bulk send, and each API send that sets consent_attested, to how many recipients, and when. It does not store each contact's opt-in wording or time. Your signup form or store keeps that record. (A contact who signs up on a Ready-hosted opt-in page is the exception: Ready stores that sign-up, with the time, IP address and exact wording, and support@tryready.com can send you a copy.)
For platforms, the same controls come through the API: POST /v1/messages with consent_attested: true, plus opt-out and scrub endpoints. See the messages API docs.
The practical takeaway
Start by working out where your audience actually reads messages. For a US list, SMS reaches nearly everyone, and the costs are predictable once you understand segment math. WhatsApp is worth adding when a meaningful share of your customers live in it, especially international ones.
If you want to test SMS, your first 20 texts on Ready are free. They're one-to-one sends, so use them before you register. Campaigns are paid from the first text, and to send any text you need a card and a number ($2 a month, the first month charged when you get it). You can sign up here and send a few to yourself to check how your copy splits into segments.