About FigureMill
Free calculators for building materials, heating and cooling, and the recurring costs of owning a home — each built to answer one question quickly, privately, and with the formula visible.
Who maintains this site
My name is Xiaojie Liu. I am a PhD student in computer science at Xinjiang University.
I am not a contractor, an HVAC technician, a structural engineer, or a tax professional. Nothing on this site is professional advice, and no page has been reviewed by someone who is licensed in any of those fields. If your project needs a stamped drawing, a load calculation you can submit for a permit, or a tax position you can defend, hire the person who does that for a living.
What I can do is narrower, and worth stating plainly: make sure the arithmetic is right, publish the formula each page uses, and trace every input back to a named standard rather than a rule of thumb. Where a page cannot be reliable, it says so in a Limitations section instead of rounding the uncertainty away.
Why the site exists
Most material calculators return a single number and nothing else — no indication of the bag yield it assumed, no allowance for waste, no note that the answer changes with slab thickness. Several of them disagree with each other on the same inputs. FigureMill was built to fix the part that is fixable: show the work, name the source, and state the boundary.
Where the numbers come from
Every calculator page ends with a sources line, and those sources are linked so you can check them. The recurring ones:
- Concrete quantity and bag yield — published coverage charts from bagged-mix manufacturers
- Rebar spacing, cover, and lap — ACI 318
- Board feet and nominal lumber sizes — North American nominal sizing conventions
- Heating and cooling load — ACCA Manual J methodology; equipment sizing ranges from ACCA guidance
- Duct sizing — ACCA Manual D friction-rate method
- Operating cost comparisons — DOE fuel energy content and AFUE / HSPF / SEER2 efficiency ratings
- Mortgage interest and property tax — IRS Publication 936 and state revenue department schedules
- Self-employment tax — IRS Schedule SE and the SSA annual wage base
Where a figure changes year to year — the Social Security wage base, standard deductions, efficiency minimums — the page states the value it used so you can compare it against the current publication.
What these calculators are not
They are estimates. A real project depends on local code, soil bearing capacity, climate zone, ceiling height, window area, insulation, and equipment you have not chosen yet. Each page has a Limitations section that says where its answer stops being trustworthy — read that before you order material or sign a contract.
How the tools are built
The site is static HTML, CSS, and JavaScript. There is no backend, no database, and no server-side calculation. Every number you type is processed in your browser and never transmitted.
Privacy
No account, no email capture, no newsletter popup, no cookie wall. Measurements, mortgage balances, and income figures stay on your device. See the privacy policy for the current detail.
Corrections
If a result disagrees with an authoritative source, or a formula is wrong, I want to know — corrections take priority over new pages. Write to liuxj412412@gmail.com and include the page and the inputs you used. Pages that get corrected show a revised updated date.
Advertising
FigureMill does not currently run advertising. If ad space is introduced later, it will sit in fixed-size containers so pages do not shift while loading, and no advertiser will have any influence over a result or a ranking.
What is next
New calculators are added when a page can do one job better than what already ranks for it. Suggestions are welcome, especially from people who use these numbers at work and know which edge cases break first.