Why this site exists
Getting paid involves a surprising amount of small, easy-to-get-wrong maths: when does a Net 30 invoice actually fall due? What price keeps a 40% margin after that discount? How much VAT is inside this gross figure? Every tool here answers one of those questions instantly, with the formula explained on the same page so you can check the working.
What you can do here
- Dates & deadlines — invoice due dates (Net 7–90, EOM, custom), a business days calculator and a date calculator for days between dates, adding or subtracting days, and working-day counts.
- Invoicing — a printable invoice generator and a bulk due-date tool for spreadsheet users.
- Tax — a UK VAT calculator and a US sales tax calculator with state base rates.
- Pricing — profit margin, markup and discount calculators that also show the margin behind a promotion.
How we build and verify our calculators
Every calculator on TermCalc is built the same way, and the method matters more than a badge:
- Formulas come from primary sources — statutory text (the UCC for payment terms, HMRC Notices for VAT, OPM for federal holidays, FTC rules for pricing claims), not from other websites. Each page lists the primary sources it used, and the date that page was last reviewed.
- Every engine ships with a test suite. Our date and money engines run 100+ automated assertions covering leap years, month-end boundaries, weekend rollovers and cross-year spans. A calculation that has never been tested is not allowed on this site.
- Worked examples are computed, not invented. Every figure in the examples on our pages was produced by the same engine you can use in the tool above — if the page says $60 at 40% margin prices at $100, that came out of the code, not a textbook.
- Each page carries a review date and is re-checked when the underlying rule changes — most visibly the federal holiday table, which is maintained through 2028 with observed-date handling.
Found a figure you believe is wrong? Email xtwh888@gmail.com with the page and the number — corrections are applied and re-verified the same week. This is how we earn accuracy rather than claim it.
Who runs TermCalc
TermCalc is an independent, self-funded project run by a small team that has spent years doing exactly what the tools here support: invoicing clients, chasing due dates and arguing about margins. There is no venture capital and no data business model — the site is funded by the advertising slots, and your inputs are never sold or profiled because they never leave your browser.
Our data promise
Every calculation runs locally in your browser. Nothing you enter — dates, terms, invoice lists or prices — is uploaded, stored, or shared. There are no accounts and no tracking cookies from us. Read the details in our Privacy Policy.
Disclaimer
TermCalc provides date and money calculations for general informational purposes only. Results do not constitute financial, legal, tax, or accounting advice. The binding due date for any invoice is whatever you agreed with your customer or supplier — always check the actual contract when money is on the line.
Contact & suggestions
The site is operated by the TermCalc team. Reach us at xtwh888@gmail.com — or faster: use the suggestion box at the bottom of every page. User suggestions decide what we build next.