usefulweb.site Is It Worth It?

Everyday problem-solving

Is It Worth It?

Buy, rent, repair or subscribe? Compare total cost and NPV over the years you need it.

years
%/year

What money is worth to you per year (e.g. savings interest). Used for NPV only.

Shown in results only; no conversion is performed.

Options (required)

Costs are positive numbers. Resale is what you expect to get back at the end. One-off year 0 = at the start.

Options
#OptionTypeUpfront costRecurring / monthOne-off costsOne-off in yearResale at endRepair allowance / year
1
2
3
4

Try an example: Washing machine: buy, rent or repair the old one (5 years) · Design software: perpetual licence vs subscription (4 years)

How it works

Enter the options you are considering (buy new, rent, repair what you have, subscribe) with upfront, monthly and one-off costs, resale value and a repair allowance. The tool computes total cost of ownership, net present value of costs, cost per month, a ranking and when the best option overtakes the runner-up.

  • Annual running cost = recurring per month × 12 + repair allowance per year.
  • Total cost (nominal) = upfront + one-off costs + years × annual running cost − resale value.
  • NPV cost = upfront + one-off ÷ (1 + r)^y + Σ(t = 1..N) annual running cost ÷ (1 + r)^t − resale ÷ (1 + r)^N, where r = discount rate and y = the one-off year (running costs are discounted at each year end).
  • Cost per month = total cost ÷ (12 × years); NPV cost per month = NPV cost ÷ (12 × years).
  • Options are ranked by NPV cost (lowest first); ties keep input order.
  • Break-even: nominal cumulative costs of the best and runner-up options are compared at each year end (resale counted only at the end, one-off costs from their year) and the crossing point is interpolated linearly.

For scripts and AI agents

  • JSON API: POST https://isitworthit.usefulweb.site/api/v1/calculate (same calculation as this page)
  • Interface description: OpenAPI 3.1 · AI guide: llms.txt
  • MCP server (Streamable HTTP): https://isitworthit.usefulweb.site/mcp · tool name is_it_worth_it
Example request
curl -s -X POST https://isitworthit.usefulweb.site/api/v1/calculate \
  -H 'content-type: application/json' \
  -d '{"years":5,"discountRatePercent":3,"currency":"EUR","options":[{"name":"Buy new","kind":"buy","upfront":650,"resale":100,"repairPerYear":20},{"name":"Rent","kind":"rent","monthly":15,"oneOff":30},{"name":"Repair old","kind":"repair","upfront":220,"repairPerYear":60,"oneOff":650,"oneOffYear":3}]}'
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