Fax API Pricing: Per-Page vs. Subscription Compared (2026)

By Sarah Martinez · Published July 10, 2026 · Updated July 10, 2026 · 9 min read

Quick Answer: For under 300 pages/month, a pure pay-as-you-go API (Telnyx, Notifyre, or Phaxio) usually costs less. Above 300 pages/month, a subscription like mFax Business is almost always cheaper — and includes a virtual number, signed BAA, and team dashboard that PAYG APIs charge extra for.

Fax API pricing doesn't work like most cloud APIs. There's no single "per-request" model that everyone follows. Some providers charge $0.007 per page with no monthly fee. Others charge $40/month for 1,500 pages. A few bill per minute of transmission instead of per page. And the cheapest raw per-page rate isn't always the cheapest total cost once you add number rental, HIPAA compliance fees, and overage charges.

This guide breaks down every major pricing model, compares actual rates across providers, and gives you the break-even math so you can pick the right structure for your fax API integration. For a technical deep-dive on the mFax API itself, see our complete fax API guide.

The Two Main Fax API Pricing Models

Per-Page (Pay-As-You-Go)

You pay a fixed rate per page sent or received — typically $0.007 to $0.10 per page — with no monthly minimum. The meter only runs when faxes move.

Best when: volume is low, unpredictable, or seasonal. Ideal for dev/test environments, integrations where fax is an edge case, or MVP builds before you know your production volume.

Watch out for: number rental fees ($2–5/month per virtual number), international surcharges (usually +50%), and missing features like team inboxes or HIPAA BAAs.

Subscription (Monthly Fee + Page Allowance)

A flat monthly fee that includes a set number of pages per month. Overage is billed per page above the limit. Usually bundles a virtual fax number, team dashboard, and compliance features.

Best when: volume is consistent (300+ pages/month), you need a permanent inbound number, or your integration requires HIPAA compliance and a signed BAA.

Watch out for: overage rates (which can be 2–10x the base per-page rate), inbound/outbound page splits that count against the same allowance separately, and API access being locked to higher tiers.

Usage-Based (Hybrid)

Some providers — most notably mFax — don't fit neatly into either category. Usage-based pricing applies a predictable formula (seats × rate + pages × rate) rather than a fixed tier or pure PAYG. You set exactly the seats and pages you need, the price scales proportionally, and there are no tier jumps.

Per-Page Fax API Providers

Telnyx — $0.007/page

Telnyx offers the lowest published per-page rate for a fax API, at $0.007/page for both outbound and inbound domestic faxes. There's no monthly subscription required.

The catch: Telnyx's per-page fee doesn't include SIP Trunking transmission costs, which are added separately based on call duration and destination. The true all-in cost per page is therefore higher than the advertised rate, and varies by fax length. At low volumes the total is still very competitive.

Volume discounts are available via contract for high-volume senders, but exact thresholds require a sales engagement.

Notifyre — $0.03/page

Notifyre is a straightforward PAYG fax API with a published rate of $0.03/page. There's no monthly subscription — you fund your account with a $10 minimum deposit and pages are deducted as you send. HIPAA compliance and BAA are included.

Separate fax number plans are required if you need an inbound number, but they're available as add-ons. For pure outbound API use with no inbox requirement, Notifyre is one of the simplest per-page options available.

Phaxio (Sinch) — $0.07/page

Phaxio — now part of Sinch — charges $0.07/page for domestic US and Canada faxes, $0.10/page internationally. There's no monthly fee, and volume discounts kick in at 50,000+ pages/month ($0.05) and 100,000+ pages/month ($0.04).

Phone number rental is $2/month per number. HIPAA BAAs are included at no extra charge. Phaxio is one of the most established fax APIs with a large developer community and clean documentation.

Subscription Fax API Providers

mFax — ~$9/mo (Usage-Based)

mFax Business uses a usage-based pricing formula rather than fixed tiers: $3/seat/month + $4 per 100 pages/month, with a 20% discount on annual billing.

The entry plan (1 seat + 200 pages/month, billed annually) works out to ~$9/month — roughly $0.045/page at baseline. As your volume grows, you add pages in 100-page increments at $4 each, so the effective per-page rate stays consistent.

Every mFax Business plan includes:

• Full REST API access (no higher tier required)
• Virtual fax number — no separate rental fee
• Signed HIPAA BAA at no extra cost
• Web, mobile, and desktop dashboard for non-developer staff
• API documentation at developers.mfax.to

For teams building integrations that also need human-usable faxing alongside the API, this bundled model is a genuine differentiator. See our fax API code walkthrough for implementation details.

iFax Pro — $25/mo (1,000 pages)

iFax offers subscription plans starting at $8.33/month, but API access is locked to the Pro plan at $25/month (billed annually) or $33/month month-to-month. That plan includes 1,000 pages/month and overage at approximately $0.01/page.

For pure developer use where you need 500–1,000 pages/month and don't need team features, iFax Pro is competitively priced. Below 500 pages, the economics favor a PAYG option.

WestFax Team — $39.95/mo (1,500 pages)

WestFax's Solo plan ($14.95/month) excludes API access entirely. API access starts with the Team plan at $39.95/month, which includes 1,500 pages/month, 5 users, and a HIPAA BAA. Overage is $0.03/page.

For enterprise deployments that need high page volumes and dedicated account management, WestFax offers custom enterprise rates as low as $0.015/page. But for most API developers, the $39.95 minimum before API access is a meaningful barrier.

eFax — $16.95/mo (limited API access)

eFax's consumer and small-business plans include limited API-like features, but a proper developer fax API integration requires the Business plan ($39.99/month + $10 setup fee) or the Enterprise tier (custom pricing). Overage rates on eFax are among the highest in the market: $0.07–$0.10/page above the included allowance.

eFax also splits its page allowance between inbound and outbound separately — a plan with 200 inbound and 300 outbound pages can exhaust the inbound allowance while the outbound pages sit unused.

FAXAGE — $3.49/mo (bills per minute, not per page)

FAXAGE uses a unique model: it bills per minute of transmission, not per page. The entry plan ($3.49/month + $5 setup) includes 300 inbound + 300 outbound minutes. Overage is $0.05/minute.

For single-page faxes transmitted in under 30 seconds, this can be cheaper than per-page billing. For long documents (10+ pages at standard resolution), a minute-based model can cost more. API access is included on all FAXAGE plans at no extra charge.

Full Provider Comparison

*mFax effective per-page rate at entry plan (200 pages for ~$9/mo).

Break-Even: PAYG vs. Subscription

The break-even point depends on which PAYG provider you're comparing. Here's the math against the two most-used options:

The key insight: Telnyx PAYG is cheaper than any subscription for very low volumes. But Telnyx doesn't include a fax number (add $2–4/month), and SIP fees add to the per-page cost. Once you factor those in, mFax's subscription becomes competitive around 200–300 pages/month.

Against Phaxio, the subscription wins as early as 130 pages/month at mFax's entry price of $9.

5 Hidden Costs to Watch For

The advertised rate is rarely the total cost. These costs often don't appear in the headline pricing:

1. Fax number rental Most PAYG APIs don't include a virtual fax number. Phaxio charges $2/month, Telnyx charges separately. If you need an inbound number — for receiving faxes via webhook — add this to your PAYG cost.

2. API access gates WestFax's Solo plan ($14.95/month) and iFax's Basic/Plus plans exclude API access. You may pay for a plan and discover the API is not available until you upgrade.

3. Inbound/outbound page splits (eFax) eFax splits its monthly allowance into separate inbound and outbound buckets. A plan with 200 inbound + 300 outbound pages can hit the inbound limit while outbound pages sit unused. This double-counts volume against you.

4. Overage rates eFax charges $0.10/page in overage — compared to their base rate, that's 3–7x more expensive per page for anything above the plan limit. WestFax charges $0.03/page in overage. Always check the overage rate, not just the plan price.

5. International fax surcharges Every provider charges a premium for international faxes. Phaxio goes from $0.07 to $0.10/page (+43%) for international. Budget for this separately if your integration sends to international numbers.

Which Model Is Right for Your Integration?

Choose per-page (PAYG) when:

• Monthly volume is under 200 pages — you're in dev/test, building a prototype, or fax is an edge case in your app
• Your fax traffic is unpredictable or seasonal — a medical portal that only faxes during open enrollment, or a legal app that faxes based on case volume
• You need zero commitment — some integrations run for months without a single fax; a subscription wastes money during those stretches
• Best pick: Telnyx for lowest raw rate; Notifyre for simplicity without SIP cost confusion

Choose subscription when:

• Monthly volume is consistent at 300+ pages — the math reliably favors a subscription at this point
• Your API integration runs alongside a human-facing fax inbox — subscription plans include a team dashboard; PAYG APIs don't
• You need a permanent inbound fax number with webhooks — number rental on PAYG plans is a recurring add-on; subscriptions include it
• Compliance is non-negotiable and you want everything in one contract — BAA, encryption, audit logs
• Best pick: mFax Business for volume flexibility and bundled features; WestFax for high-volume enterprise

Choose usage-based (mFax) when:

• Your volume is predictable but growing — you don't want to pay for a 5,000-page enterprise plan when you use 400 pages
• Your team needs both API access and a portal — developers use the REST API; staff use the web and mobile apps under the same plan
• You want to right-size exactly without worrying about tier jumps

For applications in healthcare, legal, or finance that need the API alongside compliant team workflows, mFax Business is the most complete bundle. Every plan includes the mFax REST API, a virtual number, signed BAA, and web/mobile/desktop access — no separate API tier, no number add-on, no BAA upgrade required.

Get Started

Compare your expected monthly volume against the break-even table above, then pick the model that matches your trajectory — not just your current state. An integration that starts at 50 pages/month often grows to 500 once it's in production.

For teams that need a fax API with room to grow, mFax Business starts from about $9/month. Use the live calculator on the pricing page to set your exact seats and pages — no sales call required. Full API documentation is at developers.mfax.to.

If you're just starting and want to see the API in action first, our send-fax-via-API tutorial has copy-paste code in cURL, Node.js, Python, and PHP.