One monetary amount, one tax rate
NettoKlar calculates gross, net and percentage-based tax for a single amount using a rate you choose. Calculations run locally in your browser and assume that one rate applies to the entire net amount. Choose EUR, USD, GBP or CHF as the display currency. Changing the currency does not convert amounts or apply an exchange rate. The calculator determines neither the legally appropriate tax rate nor a tax liability in any country. The initial 19% and the preset buttons are illustrative examples.
Three calculation directions
- Enter gross
- Net = Gross ÷ (1 + Tax rate ÷ 100). Net is rounded to two decimal places. Tax = Gross − Rounded net.
- Enter net
- Tax = Net × Tax rate ÷ 100, rounded to two decimal places. Gross = Net + Rounded tax.
- Enter the tax amount
- Net = Tax amount ÷ (Tax rate ÷ 100), rounded to two decimal places. Gross = Net + Entered tax amount. At 0%, this reverse calculation has no unique answer and is rejected.
Rounding and accuracy
All supported currencies use two decimal places in this tool. Monetary values are processed as whole numbers of hundredths of the selected currency unit. The calculation engine uses integer fraction arithmetic, avoiding floating-point errors in the formulas. Half-unit fractions are rounded up for the supported non-negative values. The three displayed amounts always satisfy: Net + Tax = Gross.
This rounding convention is a deliberate technical choice, not a claim that every invoice must use this rounding method. Multiple line items or rounding each invoice line may produce different totals. For example, €0.03 net at 19% becomes €0.04 gross after rounding. In the reverse direction, €0.03 gross at 19% appears as €0.03 net and €0.00 tax. Rounding to two decimal places is not always reversible.
If an already rounded tax amount is used as the starting point, the result is only a mathematical approximation. It does not prove which net amount appeared on the original invoice.
Inputs and limitations
- Amounts from 0 to 999,999,999.99 in the selected currency. The result must not exceed this limit either. Currency selection changes the label and formatting, not the numeric amount.
- Up to two decimal places. Both 1,234.56 and 1234.56 are supported. Use a period as the decimal separator and commas to group thousands: 1,234 = 1,234.00.
- Tax rates from 0 to 100%, with up to two decimal places. Rates accept either a decimal period or a decimal comma; English output uses a decimal period.
- Negative amounts, credit notes, scientific notation and currency symbols in the input are not supported.
- No tax classes, income tax on wages, social security contributions, multiple invoice items, discounts, mixed or compound tax rates, or assessment of tax deductions. No country-specific tax rules, exchange rates or cash-payment rounding rules are applied.
Examples to check
| Input | Rate | Net | Tax | Gross |
|---|---|---|---|---|
| €119 gross | 19% | €100.00 | €19.00 | €119.00 |
| €100 gross | 19% | €84.03 | €15.97 | €100.00 |
| €107 gross | 7% | €100.00 | €7.00 | €107.00 |
| €100 net | 19% | €100.00 | €19.00 | €119.00 |
| €1 tax | 19% | €5.26 | €1.00 | €6.26 |
Mathematical basis and verification
The formulas follow from Tax = Net × Rate ÷ 100 and Gross = Net + Tax. Rearranging these identities gives the three calculation directions above. No national tax-rate schedule or legal classification is used.
The calculation code is tested against example amounts, boundary cases and rounding behavior. Technical tests do not constitute official certification, tax advice or a guarantee that a result satisfies local invoice requirements. The example rates and EUR figures illustrate the arithmetic only.
Responsibility and updates
The calculator does not replace an individual assessment or tax advice. Despite careful technical testing, there is no guarantee that it is free of errors or suitable for tax purposes in any particular case. Check applicable rules independently; the calculator does not establish compliance with any country’s tax law.
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