Add two or more numbers or compatible measurements, with automatic unit conversion, precise calculation steps, and downloadable results.
Enter between 2 and 20 values. Commas and scientific notation are supported.
General formula: S = x₁ + x₂ + ... + xₙ S = sum xᵢ = each entered value n = number of values
| Item | Entered | Converted | Running Total |
|---|---|---|---|
| — | — | — | — |
For plain numbers, the calculator adds the entered values directly. For measurements, each value is first converted to a consistent internal base unit. The base-unit values are added with full JavaScript numerical precision, and the total is then converted to the selected result unit.
The general formula is S = x₁ + x₂ + … + xₙ, where S is the total, each xᵢ is an addend, and n is the number of values. For unit-aware addition, each addend is converted using bᵢ = xᵢ × fᵢ, where fᵢ is its base-unit conversion factor. The final displayed total is Sᵤ = (Σbᵢ) ÷ fᵤ.
Adding 1.5 metres, 75 centimetres, and 2 feet requires a common unit. In metres, the values are 1.5 m, 0.75 m, and 0.6096 m. Their sum is exactly 2.8596 m, which displays as 2.86 m when rounded to two decimal places.
The Total card shows the rounded result in the selected output unit. The exact internal result retains additional significant digits for inspection. Average is the total divided by the number of valid addends, while Range is the largest converted value minus the smallest converted value.
Length uses metres, mass uses kilograms, duration uses seconds, and digital storage uses bytes as internal base units. Decimal storage units use powers of 1,000, while binary units use powers of 1,024. Very large or very small results may be displayed in scientific notation to remain readable.
Yes. Negative values are valid and reduce the total. The visual separates positive and negative contributions where applicable.
Yes, provided all values represent the same type of quantity, such as several lengths or several durations.
The exact result shows more available precision, while the primary total follows the selected decimal-place and rounding settings.
No. Calculations, saved settings, sharing data, and file creation are handled locally in your browser without network requests.
This calculator is suitable for general arithmetic and routine measurement conversions. JavaScript uses IEEE 754 floating-point arithmetic, so extremely large values, extremely small values, or calculations requiring regulated financial, scientific, engineering, or legal precision should be independently verified with an appropriate specialist system.