Cobalt Tools

Free Online Calculators

Calculate percentages, energy costs, budgets, savings, date intervals, units and more. Free local calculators, with Romanian salary and VAT scenarios clearly identified.

Free · No account · Local calculations

Monetary amounts are in Romanian lei (RON) unless another currency is selected. Salary and VAT calculators use Romanian rules; changing language does not switch tax jurisdiction.

All calculators in one place

11 calculators

Percentage and Discount Calculator

Calculate discounts, percentages, proportions and percentage changes. Enter your own values and see the formula and result instantly.

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Electricity Cost Calculator

Estimate appliance energy use and monthly cost from power, hours and your tariff. Default examples use Romanian lei; no live electricity price is implied.

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Monthly Budget Calculator

Compare monthly income and household expenses to see your remaining budget or deficit. Currency examples use Romanian lei (RON).

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Savings and Compound Interest Calculator

Simulate monthly contributions and interest at a constant rate. Compare your contributions with interest; taxes, fees and inflation are not included.

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Days Between Dates Calculator

Count calendar days and Monday-to-Friday days between two dates. Optionally include the end date. Public holidays are not subtracted.

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Unit Converter

Convert length, area, mass, volume and temperature in both directions. Read the conversion formula and copy the result.

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Romanian VAT Calculator

Add or extract Romanian VAT with editable rate presets. Changing language does not change the Romanian tax jurisdiction.

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Romanian Net and Gross Salary Calculator

Estimate Romanian net or gross salary under the standard tax scenario, with a manually entered deduction. This is not a payroll statement or a foreign tax calculator.

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Mortgage Payment Calculator

Compare equal and declining mortgage payments at a fixed interest rate. Choose RON or EUR as the scenario unit; this does not perform currency conversion.

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Construction Material Calculator

Estimate concrete volume, tile boxes or paint litres with your dimensions and reserve percentage. This is a quantity estimate, not structural design.

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Fuel and Trip Cost Calculator

Estimate fuel quantity, trip costs and cost per passenger from your distance, consumption and price. Default examples use Romanian lei (RON).

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Start with an example

Fields are prefilled so you can see how it works.

Adjust what matters

Enter your values. The result updates instantly.

Understand and keep the result

Read the formula and copy your results.