About AstraCalculator

AstraCalculator is a small independent site that answers the everyday questions people put into a search box with a number in them. How much will this loan cost. How many bags of mulch. What is left of a bonus after tax. How many days until the deadline.

It started from a simple frustration: nearly every calculator online gives you one number and no reasoning, so you still cannot tell whether to trust it.

What makes these different

Every calculator here shows the arithmetic it used, in plain language, under the answer. A materials page that tells you to buy 25 bags also tells you how many cubic feet that is and what a bag is assumed to hold. A tax page names the bracket every dollar fell into. You can check the working against the label in the store or against the IRS table, which is the whole point.

Each one also returns the things people forget: the fabric under the stone, the payroll tax a 401(k) does not avoid, the closing costs that come on top of a down payment. Those are the items that send you back to the store on a Saturday, or produce a bill you were not expecting.

Nothing here asks you to sign up, and the numbers you type stay in your browser. They are put into the address bar so you can send a result to somebody, and that link is the only place they go.

Where the numbers come from

Volumes, areas and dates are straight arithmetic. Materials use published trade figures: bag yields printed on the bag, densities in pounds per cubic yard, standard coverage rates and normal waste allowances. Finance pages use the standard formulas - the amortized payment, compound growth - and name them. Health pages name the formula too, because Mifflin-St Jeor and Harris-Benedict do not agree and you deserve to know which one you are reading.

Tax pages carry the current federal figures, and every one of them lets you type in a different year's numbers, because a tax table is a fact about a year rather than a piece of math. Where a figure genuinely varies, it is a field you can change rather than a hidden assumption, since the honest answer is that it depends.

Estimates are estimates. Real material varies with moisture, compaction and supplier. Tax depends on circumstances no calculator can see. Nothing here is professional advice, and for anything that matters, check it with somebody who is responsible for the answer.

How the site is paid for

Advertising. There is nothing to buy here, no account to make, and no email to hand over. See the privacy policy for what advertising means for your data.

Found a mistake?

Tell me and I will fix it. A calculator that is wrong is worse than no calculator, so corrections are genuinely welcome: get in touch.

There are 131 calculators on the site today, and more are added every week.