Chimney TopDigital Services

Available now

Chimney Top Calculators

Calculators that show their work.

Free

No account needed. Calculations run in your browser.

Open the calculatorsCompare plans

Paid prices are in US dollars; sales tax may be added at checkout.

Narrow, technical calculators with the formula, a worked example and the sources on every page. Results update as you type, and every result has a link you can share.

Free calculators for equipment cost, radiation dose rate, decay and GPU hosting, with answers that update as you type. 1:17 · no sound, captions on screen.
Read the captions
  1. Chimney Top Calculators. Free, fast calculators for radiation safety, equipment costs and hosting. Answers update as you type. No sign-up, no tracking by default.
  2. Free calculators at calculators.chimneytopdigital.com
  3. Equipment cost per hour: what a machine really costs you to run.
  4. Enter the purchase price, resale value, hours, fuel and upkeep…
  5. …add the operator’s wage, and the hourly cost updates instantly.
  6. Radiation dose rate: for gauge users and radiation safety officers.
  7. Change the source activity and the dose rate follows: 2 Ci of Cs-137 at 1 m.
  8. Switch units in one click. Every result links back to its formula and sources.
  9. Radioactive decay: how much activity is left after a given time.
  10. One Co-60 half-life later, 10 mCi is down to 5 mCi.
  11. GPU hosting profitability: what a rented GPU earns after power.
  12. Pick a card, set how many, and see the monthly profit.
  13. Plus free study guides and practice quizzes.
  14. Free at calculators.chimneytopdigital.com. Works on any phone or computer. Results are shareable by link.

Open the calculators

The equipment cost per hour calculator: enter what the machine cost and what it burns, and the owning and operating cost per hour updates as you type. Mock-up with made-up data; the released screen may differ.

What it does

  • Gamma dose rate, activity and shielding: a point source through lead, steel or concrete, or solve for activity, distance or shield thickness.
  • Radioactive decay and half-life: remaining activity, elapsed time, original activity or half-life.
  • Radiation unit converter: Sv and rem, Gy and rad, Bq and Ci.
  • GPU and CPU hosting profitability: net per hour, per month and break-even against your power cost.
  • Equipment cost per hour: the owning and operating cost of any machine.
  • Free, with no sign-up, and everything runs in your browser.

Who it is for

Radiation workers, engineers and students; homelab owners renting out spare GPUs or CPUs; small contractors costing their equipment.

Availability

Live now at calculators.chimneytopdigital.com: free to use, with no account.

Good to know

Calculators give educational estimates from published formulas and constants. They are not professional, medical, regulatory or financial advice. Check the sources on each page.

Educational estimate — not for medical/clinical or regulatory dose assessment. Results come from idealized point-source formulas and published constants that vary by 5–20 % between references. Do not use them for patient dosimetry, licensing, shielding design sign-off or to decide whether an area is safe to enter. Use a calibrated survey instrument and your radiation safety officer for those decisions.

Planning estimate. Your own records (fuel logs, repair invoices, insurance bills) beat any default. This is not tax or accounting advice — depreciation for taxes follows different rules.

Connect an AI assistant

Chimney Top Calculators offers its calculations to AI assistants over the Model Context Protocol: 10 free, read-only tools, no account needed. How to connect, and what the tools do.

Related guides

All products and demos · Pricing · Support