Comparing subscription offers with a small, auditable cost function

Tihmlo — Sun, 15 Nov 2026 20:41:57 +0000

A lower monthly price can hide an upfront fee or a longer commitment. A comparison tool should show its assumptions before ranking offers.

Start with explicit inputs

For a fixed evaluation period, keep the upfront cost, monthly charge, number of months and unconditional credits separate. Do not subtract a conditional rebate until its conditions are met.

function totalCost({ upfront, monthly, months, credits = 0 }) {
  const values = [upfront, monthly, months, credits];
  if (!values.every(Number.isFinite)) throw new Error("Use finite numbers");
  if (values.some(v => v < 0)) throw new Error("Use non-negative inputs");
  if (!Number.isInteger(months)) throw new Error("Use whole months");
  return upfront + monthly * months - credits;
}

A synthetic example

Offer A: zero upfront plus $85 per month for 24 months = $2,040. Offer B: $600 upfront plus $40 per month for 24 months = $1,560. The difference is $480 before taxes, fees or financing. These are illustrative numbers, not current carrier offers.

Test the boundary cases

Zero months should return upfront minus credits.
Zero upfront cost is valid.
Negative values, infinity and missing numbers should be rejected.
A credit larger than the modeled cost should trigger a review of the assumptions rather than an automatic claim of profit.

For production currency calculations, store integer minor units and define rounding at the input boundary. Keep taxes, termination fees, financing, price changes and device resale value as separate visible assumptions when they apply.

Preserve the explanation

Show the formula and the selected time horizon alongside the answer. A result should be reproducible from the displayed inputs. Do not treat an estimated total as a guarantee of the final bill.

This is the kind of transparent comparison logic I explore through TIHMLO. The code and numbers above are demonstrations.

Disclosure: this article was prepared with AI assistance and reviewed for arithmetic and scope.

A five-person AI subscription is a break-even problem, not a seat-price problem

Tihmlo — Thu, 12 Nov 2026 03:52:18 +0000

A per-seat price is easy to quote. It is not the same thing as the cost of adopting a tool—or proof that the tool pays for itself.

For a five-person team, the useful question is:

Will the team save enough reviewed, usable work time to cover the subscription and the overhead of introducing it?

Start with published seat prices

Public US pricing checked on November 11, 2026:

Plan	Monthly billing	Annual billing	Five-seat annual cash cost
ChatGPT Business	$25 per user/month	$20 per user/month	$1,500 monthly-billed or $1,200 annual-billed
Claude Team	$30 per person/month	$25 per person/month	$1,800 monthly-billed or $1,500 annual-billed

Claude Team currently has a five-seat minimum. ChatGPT Business has a two-seat minimum. Taxes, promotions, features, and usage policies can change, so verify the vendor pages before purchasing.

Add the cost most comparisons omit

Assume five people spend two hours each on onboarding, policy review, prompt patterns, and basic workflow setup. At a loaded labor cost of $40 per hour:

5 people × 2 hours × $40 = $400

That makes the first-year example:

ChatGPT Business, annual billing: $1,600 including onboarding
Claude Team, annual billing: $1,900 including onboarding

This still excludes integration work, administration, review time, and any work that cannot be sent to the tool.

Convert the bill into a break-even target

Use one simple formula:

required hours saved per month = monthly subscription cost ÷ loaded hourly labor cost

For five ChatGPT Business seats billed monthly:

$125 ÷ $40 = 3.13 team-hours per month

The tool does not need to eliminate a job. It needs to produce a little more than three hours of usable, reviewed time savings across the whole team every month. If correction and review take back those hours, the subscription has not cleared the bar.

Run a four-week pilot before buying annually

Choose three recurring tasks with clear inputs and outputs.
Record completion time, correction time, and review time.
Count failed attempts and work excluded for privacy, security, or policy reasons.
Retain the tool only if the measured benefit clears the subscription plus the review burden.

Examples of good pilot tasks include first-pass meeting summaries, restructuring internal drafts, or extracting fields from a repeatable document type. “Use AI more” is not a measurable task.

What price alone cannot answer

A purchasing decision should also cover:

identity and access administration;
data handling and retention controls;
export and account offboarding;
integrations with the team's actual workflow;
usage limits and model availability;
the cost of human verification.

I published the full source-linked model, a paid-seat cost calculator, a monthly-versus-annual calculator, and an AI feature-evaluation worksheet on TIHMLO:

Official pricing sources

This is a public-price and decision-model comparison, not a hands-on performance claim. Pricing and plan terms were checked on November 11, 2026.

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