ROI calculator: let the buyer check the math themselves

A page where a buyer enters their own numbers and sees cost, savings, payback and return.

Live example

The example: Route planning for a 14-van heating company

Five inputs, two stated guesses, payback in months

Route planning for a 14-van heating company

Open the exampleThe names and numbers are made up.

What to notice

  • It opens on an answer, 6.1 months to pay back, worked from the 14 vans and 65 miles a day the buyer gave on the call.
  • Only half the saved driving time is counted, and the buyer can drag that slider down to 0%.
  • A three-row table reruns year one with routes 6%, 12% and 18% shorter. At 6% the net falls from $22,560 to $1,404.

The prompt that starts one like it

Make an ROI calculator as a single HTML page for [prospect], who is weighing up [product] at [price and any setup fee]. Start it on the numbers from our call: [their figures]. Let them change each one and watch cost, savings, return and payback update. Show the working line by line, put our assumptions on sliders, add a table for the main assumption being half as good, and a one-sentence summary for their boss. It must work on a phone. Then publish it on sharable.link with a password.

A vendor's ROI calculator usually proves that the vendor's product pays for itself, and buyers know it. This one, for a 14-van heating company, tries to earn more trust: every input is the buyer's own, every guess can be moved, and the arithmetic is on the page. Its answer is only as good as the numbers and guesses that go in.

Who it's for

Salespeople and founders whose buyer likes the product but has to get the spend past a boss or a finance team. Send it after the call where you learned their numbers, with those numbers already in.

It suits a product whose saving is time or material you can count. It's the wrong tool when the benefit won't go into dollars, a rebrand for instance. The page also forgets what the buyer types: reload it and your starting figures are back.

What a good one contains

  • The buyer's figures as the starting point. The example opens on 14 vans, 65 miles a day and $46 an hour, labeled "from our call". A calculator that opens on zeros asks the buyer to do your job.
  • A hint under each input. "Last month's fuel-card report has it" says where the real number lives.
  • One answer, large. Payback in months, with year one's cost, savings, net and return beside it.
  • Guesses the buyer can move. Routes getting 12% shorter is a slider with its reason underneath. A fixed assumption is the first thing a finance person attacks.
  • The working, line by line. 14 vans × 65 miles × 250 days is 227,500 miles, and 12% of those at $0.70 comes to $19,110. Anyone can redo it.
  • A worse case. The example reruns year one at half the main guess. Better the buyer sees that from you than works it out alone.
  • What you left out. Extra jobs and fewer missed arrival windows are named and counted at nothing, which makes the counted savings easier to believe.
  • A sentence to forward. "For 14 vans, Whimbrel costs $19,752 in year one and saves about $42,300." It changes with the inputs.

When the number looks too good

The usual failure is a return so large nobody believes it. If your first draft says 900%, look for a saving counted twice, or for freed minutes all treated as revenue. Halve what you're unsure of and say that you did.

Then set both guesses to zero. This one answers "Not within 3 years." A careless one shows a negative number of months. Count your own costs in full too: here setup is charged up front and month one saves nothing.

How to send it

With a password. It sets your price against one buyer's wages and fuel costs. Your contact will forward it to whoever signs off, so choose a password that's easy to pass along.

Every page you publish gets one link that opens in any browser. You choose who can open it: anyone with the link, anyone with the password, or only the people and company domains you name, who sign in with Google or Microsoft. Change the page later and the link stays the same.

Make yours in Claude

Add the connector once, then publish from any Claude conversation and get a link to send.

Add Claude Connector

Already have the file? Upload it here.

More in sales

  • One-pager: A single page with what you offer, the proof and the next step, for a reader you won't meet.
  • Pitch deck: Ten to twelve slides, one point each, sent to investors before or after a first call.
  • Business case: The argument for funding a project: today's cost, the options, three years of numbers and the ask.
  • Pricing calculator: A page where a prospect picks a plan, seats and add-ons and watches their own price add up.
  • Comparison chart: Three or four options across the criteria that matter, with a pick for each kind of need.
  • Battle card: One competitor on one page: where you win, where you lose, and what a rep should say.
  • All use cases

Keep reading