The phone plan comparison calculator above puts three plans on the same footing by totalling everything you will actually pay over a term you choose. That means the advertised monthly price, the per-line multiplier, the account discount, the device instalment, the upfront charge, and the taxes and fees added to the service line — because the last four are where a cheaper-looking plan usually stops being cheaper.
Arb Digital builds free comparison tools that take every price as an input and publish none of their own. Carrier pricing changes constantly, differs by country and region, and is loaded with promotional terms; a page that shipped with prices would be wrong within weeks. What it can do is hold the arithmetic steady while you type in today's numbers.
What This Phone Plan Comparison Calculator Does
Each of the three plans takes five figures: monthly price per line, a monthly account discount, a device instalment, an upfront cost, and a percentage for taxes and fees. The number of lines and the comparison term are shared, because comparing plans on different line counts or different terms tells you nothing.
The tool totals each plan across the term, names the cheapest, and reports the gap to the next cheapest — which is the figure that tells you whether switching is worth the effort. The bars show the three totals side by side, and the note breaks the winner down into service, device and tax so you can see what is actually driving it.
Setting a plan's monthly price to zero removes it from the comparison, so the tool works just as well for two plans as for three.
How to Use It
- Set the comparison term. Match it to the longest device instalment plan you are considering, or to how long you realistically stay with a carrier.
- Set the number of lines. Multi-line pricing is where quoted per-line prices stop being comparable.
- For each plan, enter the monthly price per line and any account-level discount as a monthly amount.
- Add the device instalment and any upfront charge — activation, a down payment, a SIM fee.
- Enter the taxes and fees percentage from a real bill, not from the advertised price, then read the totals.
The Formula / How It's Calculated
For each plan the tool computes:
Service per month = (price per line × lines) − monthly discount.
Tax per month = service per month × tax rate.
Monthly total = service + tax + device instalment.
Term total = monthly total × months + upfront cost.
Work the defaults through over 24 months on 2 lines. Plan A is 45 × 2 = 90, less a 10 discount, so 80 of service; tax at 12% is 9.60; the device adds 12.50, giving 102.10 a month. Over 24 months that is 2,450.40, plus 50 upfront, so 2,500.40.
Plan B is 60 × 2 = 120, less 25, so 95; tax at 8% is 7.60; no device instalment, so 102.60 a month, 2,462.40 over the term and nothing upfront — 2,462.40.
Plan C is 30 × 2 = 60, no discount; tax at 5% is 3.00; the device adds 20.00, giving 83.00 a month, 1,992.00 over the term, plus 200 upfront — 2,192.00. Plan C wins by 270.40 over Plan B, despite having the largest upfront cost and the highest device instalment of the three.
That result is the point. Ranked on advertised monthly price alone the order would be C, A, B. Ranked on total cost it is C, B, A — the plan with the highest headline price comes second, and the one that looked mid-priced comes last.
Why the Advertised Price Is Almost Never the Comparable One
Four things sit between the advertised figure and the amount that leaves your account, and all four are in the calculator for that reason.
Per-line pricing is not linear. Carriers quote the price a line costs at four or five lines and show it as "per line", so a single line or two lines costs materially more than the advertised figure implies. Setting the line count explicitly is the only way to make two plans comparable.
Discounts are conditional and often temporary. Autopay discounts, paperless-billing discounts and promotional credits are frequently tied to a payment method or expire after a fixed number of months. If a discount only runs for 12 months of a 24-month comparison, enter half of it as a monthly figure rather than the full amount.
The device is a loan. A monthly instalment is repayment of a device you are buying, and it usually carries an early-termination consequence: leave early and the remaining balance falls due. That is not part of the service price and should not be compared against a plan that assumes you already own a handset.
Taxes and fees are not the sales tax you expect. Mobile bills in many countries carry line-item surcharges on top of general sales tax — regulatory recovery fees, administrative charges and universal service contributions among them. The FCC's consumer guide to understanding your telephone bill explains what those lines are and which are government charges rather than carrier ones. Take the percentage from a real bill, because the advertised price rarely includes them.
Total Cost of Ownership, Applied to a Phone Bill
What this page is really doing is a total cost of ownership comparison — a financial estimate of the direct and indirect costs of a product over its life, rather than its purchase price. The concept exists because acquisition price is a poor predictor of lifetime cost, and mobile plans are a textbook case.
The three components pull in different directions. A low monthly price with a large upfront cost front-loads the spend; a zero-upfront plan with a device instalment spreads it; a plan with a big discount that expires halfway through hides it. Only a total over a fixed term makes them commensurable.
Choosing that term is the one judgement call. Comparing over 24 months when one plan's device instalment runs 36 months flatters that plan, because you stop counting before the payments end. The safest approach is to compare over the longest commitment in the set, then check the shorter term as a second scenario.
How This Differs From Our Subscription Cost Calculator
Arb Digital's subscription cost calculator totals flat recurring fees across any number of services and projects them forward. It is the right tool for a list of streaming, software and membership charges, and it treats each one as a single repeating amount.
A mobile plan is not that shape. It has a per-line multiplier, an account-level discount that is not per line, a device loan running alongside the service at a different tax treatment, and an upfront charge — four structures the subscription tool has no fields for. This page exists to handle those, and to compare three of them at once rather than adding up a list. If your phone bill is genuinely a flat monthly figure with no device and no lines to multiply, the subscription tool is the simpler choice.
For the wider budget, the budget calculator places the winning figure among your other outgoings, and the data usage calculator answers the question this page cannot: how much data you actually need, which is what should narrow the shortlist before you start comparing prices at all.
Arb Digital designs and builds free interactive calculators that take every price as an input, publish none of their own, and earn links because they are genuinely useful. Browse what we have already published, or tell us what your audience keeps searching for.
Browse the Free Tools Hub Talk to Arb DigitalCommon Mistakes to Avoid
- Comparing advertised per-line prices at different line counts. Quoted rates usually assume four or five lines. Fix the line count first, then compare.
- Counting a temporary discount for the whole term. If a credit runs 12 months of a 24-month comparison, enter half of it. Otherwise the total is simply wrong.
- Comparing a device-instalment plan against a bring-your-own plan. One includes a phone and one does not. Either add the handset's cost to the second plan or strip the instalment from the first.
- Using the advertised price for taxes and fees. Surcharges on mobile bills are frequently several percentage points above general sales tax. Take the figure from a real bill.
- Ending the comparison before the instalments do. A 24-month comparison of a 36-month device plan stops counting a third of the payments.
Related Free Tools From Arb Digital
For a list of flat recurring fees rather than a structured plan comparison, use the subscription cost calculator. The data usage calculator sizes the allowance you actually need, the budget calculator sets the winning figure against your other outgoings, and the sales tax calculator handles the tax arithmetic on any single purchase. The break-even calculator works out when a higher upfront cost pays back, and the inflation calculator puts a multi-year total into today's money. Everything else is on the free online tools hub.
Frequently Asked Questions
Fix the line count and the term first, then total everything: service after discounts, taxes and fees on the service line, device instalments, and any upfront charge. Comparing advertised monthly prices alone reorders the plans, sometimes completely.
Usually a combination of per-line pricing quoted at a higher line count, a discount that requires autopay or has expired, a device instalment running alongside the service, and surcharges added on top of the plan price. All four are separate fields here for that reason.
It counts towards what you pay, but it is a loan for a handset rather than a service charge. Compare like with like: either include the handset cost in every plan, or strip the instalment out of all of them.
The longest commitment in the set. Comparing over 24 months when one plan's device runs 36 flatters that plan by stopping before its payments end. Check a shorter term as a second scenario.
Enter the average across the term. A discount that runs 12 months of a 24-month comparison should be entered at half its monthly value, or the total will understate the real cost.
Because that is how most mobile bills work: recurring service is taxed monthly, while a device is generally taxed at purchase and repaid as a fixed instalment. If your bill differs, fold the device tax into the instalment figure.
Yes. Set the third plan's monthly price per line to zero and it drops out of the comparison entirely.
No. Every figure is a placeholder for you to replace with the prices you have actually been quoted. Carrier pricing changes constantly and varies by country and region.
This is a cost arithmetic tool, not advice about which carrier or plan to choose. Every price is one you supply, contract terms and early-termination conditions vary, and the figures here are only as accurate as the quotes you enter.
