Family plan

A family plan (also called multi-line plan) bundles two or more cellular lines on a single account, with the per-line cost dropping as more lines are added. The economics work out because carriers prefer high-LTV multi-line accounts (lower churn, higher ARPU at the household level), so they discount aggressively to keep them.

Typical pricing curves

Per-line cost on a postpaid family plan in 2026 looks roughly like:

• 1 line: $70–90
• 2 lines: $55–70 each
• 3 lines: $45–55 each
• 4 lines: $35–45 each
• 5 lines: $30–40 each

So a four-line family on T-Mobile Magenta is about $160/month total, vs $80 for a single Magenta line. The marginal cost of each additional line drops sharply.

The catch with the cheapest family plans

To get the lowest advertised per-line price, the big-three usually require all of: (1) auto-pay enrolled, (2) paperless billing, (3) the full number of lines listed in the promo (often four or five). Drop one line and the remaining lines don't automatically reprice — they stay at the higher tier until you renegotiate or switch plans. Read the fine print.

MVNO family-plan options

MVNOs handle multi-line differently. Visible has a "Visible Party Pay" group rate that gives you their lowest per-line price as long as enough strangers join your group. Mint Mobile gives volume discounts on annual plans. Cable MVNOs (Spectrum Mobile, Xfinity Mobile) heavily discount multi-line if you're also their cable internet customer — often the cheapest family-plan option available for an existing cable subscriber.

Lines for kids and parents

Adding a child or older parent line to your existing family plan is almost always cheaper than starting them on their own carrier. Even if you switch primary lines later, keep the family plan structure for line-cost reasons. Most carriers also let you put device-finance and protection on a per-line basis, so you can have a flagship line and a budget line on the same plan without penalty.