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Calculate a percentage of a value, a part as a percentage, the missing whole, percentage changes, symmetric differences and percentage-point changes. Other modes cover reverse percentages, stacked discounts, tax-inclusive amounts, margin and markup, tip splitting and batches.

No. A rate moving from 10% to 15% rises by 5 percentage points, but the relative percentage increase is 50%. Percentage change uses the original value as its base; symmetric percentage difference uses the mean of two non-negative values.

Each percentage applies to the remaining price. On 100, a 20% discount followed by 10% leaves 72, so the combined discount is 28%, not 30%. This tool applies a purchase-wide fixed coupon afterward, then the entered tax rate, then shipping. Shipping is not taxed in this model.

Use Reverse & adjust, choose Find the original value and Decrease, then enter the final value and discount percentage. Divide the final value by one minus the discount as a decimal. A 100% reduction cannot identify a unique original price.

No. Enter the applicable rate yourself. Add tax multiplies the net amount by one plus the rate as a decimal. Extract tax divides the inclusive amount by that factor. The tool does not determine local tax rates, exemptions, registration rules or filing treatment.

Both start from profit, which is selling price minus cost. Margin divides that profit by selling price; markup divides it by cost. With cost 100 and selling price 150, markup is 50% and margin is approximately 33.33%. Other business expenses are not included automatically.

Inputs allow up to 18 integer digits and 12 decimal places, with an explicit dot or comma decimal setting and no grouping separators. Calculations keep exact decimal-input precision until a stated rounding step. Display rounding is half away from zero. Discount mode can round each stage; bill splitting uses its separate settlement precision.

An equal split may not fit the selected settlement unit. The calculator rounds the total once, then assigns the remaining small units to some shares. For example, 100 split three ways at two decimal places is one share of 33.34 and two shares of 33.33.

The calculator processes inputs in your browser. It keeps the last 10 successful calculations in page memory only, with restore and clear controls. Refreshing clears them. TXT, CSV and JSON reports contain the supplied inputs and rules; the tool does not upload them or save them automatically.

Yes. Batch mode accepts up to 200 non-empty rows or a UTF-8 TXT import up to 50,000 bytes. Enter one value per line for a shared percentage, or original;new for percentage changes. Errors remain visible in the results and exports; summary figures use only successful rows. No CSV headers or grouping separators are accepted.

Yes. In Reverse & adjust, choose Apply successive changes or Reverse successive changes. Enter up to 20 signed rates in order. A 20% increase followed by a 10% decrease combines to an 8% increase. A sequence containing a 100% decrease cannot be reversed uniquely.

A theoretical target price may need fractional currency units. Ordinary rounding can undershoot the target margin or markup. The minimum price rounds up to your chosen display precision, and the calculator shows the margin and markup achieved by that price.

In Compare, choose Percentage error. The absolute error is the absolute gap between the observed and reference values, divided by the absolute reference, times 100. A zero reference is undefined. The signed error is also shown.