Free Online Tools for the United States

Because sales tax is set locally, not nationally. Forty-five states plus the District of Columbia charge it, and counties and cities stack their own rates on top, which produces well over ten thousand distinct taxing jurisdictions. Two addresses on opposite sides of the same street can owe different amounts. Five states charge no statewide sales tax at all — Alaska, Delaware, Montana, New Hampshire and Oregon — though Alaskan boroughs may still levy their own. That is why the calculator asks you for the rate instead of guessing it from a country.

In the US, sales tax is added at the register rather than built into the displayed price. This surprises visitors from VAT countries, where the tax is already inside the number on the tag by law. So a 20.00 item at an 8.25% rate comes to 21.65 at checkout. If you need to work backwards from a total that already includes tax, divide by 1 plus the rate — 21.65 / 1.0825 — rather than multiplying the total by the rate, which gives a figure that is slightly too high.

Fifteen to twenty percent is the normal range for table service, with twenty percent common in cities and for good service. Convention is to tip on the pre-tax subtotal, though plenty of people simply use the total, and the difference is small. Tipping matters more in the US than most countries because federal law still allows a tipped minimum cash wage well below the standard minimum, with tips expected to make up the rest. The tip calculator can split a bill across several people and round each share.

It is a US peculiarity, supported by a secondary market that buys these loans from lenders so they do not have to hold thirty years of interest rate risk themselves. In most other countries a fixed period of two to five years, then a reset, is normal. Two costs the headline payment often hides: private mortgage insurance, usually required when the down payment is under twenty percent, and escrow, where property tax and homeowners insurance are collected monthly along with the payment. The calculator shows principal and interest; budget for those separately.

The exact formula is (F minus 32) times 5, divided by 9. The 32 comes first because the two scales do not share a zero — water freezes at 32F and 0C. For a quick mental version, subtract 30 and halve it: 70F gives about 20C, and the real answer is 21.1C, which is close enough to decide on a jacket. The two scales cross at minus 40, where both read the same number.

Because the US uses Letter and almost everyone else uses A4, and they are not the same shape. Letter is 8.5 by 11 inches, roughly 216 by 279mm; A4 is 210 by 297mm. Letter is about 6mm wider and 18mm shorter, so an A4 document printed on Letter loses content off the bottom, and a Letter document on A4 leaves an odd gap. When a PDF tool here asks for a page size, pick Letter for US printing, and set "fit to page" in the print dialog when you are working with a document from elsewhere.

In the US it is the fourth of March, because the American order is month, day, year. Most of the world reads the same string as the third of April. There is no way to tell from the digits alone once both numbers are twelve or under, which is why invoices and contracts crossing borders go wrong on dates so often. The safe form is either the ISO order, 2026-03-04, or spelling the month out. The date tools here show the weekday alongside the result so a misread is obvious.

There is no fixed conversion, because each school sets its own cutoffs. The common unweighted scale maps A to 4, B to 3, C to 2 and D to 1, with an A often starting somewhere between 90 and 93 percent. Weighted scales push honors and AP courses above 4.0, which is how a GPA over 4.0 appears at all. Because the mapping is a school policy rather than a national standard, the grade calculator lets you enter your own scale rather than assuming one and quietly producing the wrong number.