# Free Online Calculator for Math, Units & Dates

Calcul.io is a free online calculator for arithmetic, percentages, formulas, unit conversions, dates, currencies, and advanced math. No account required.

calcul.io / the editable calculator

## Free online calculator.

More than simple math: Calcul.io handles unit conversions, variables, functions, dates, and money in one editable workspace.

[Open calculator](https://calcul.io/app/index.md)

[See what it handles](#capabilities)

free to use

no account required

shareable calculations

```calculio
245 * 15%
5 km to miles
today + 30 days
20 EUR to USD
sqrt(144)
```

## Type the question the way you think about it.

Calcul.io stays useful when a calculation stops being one neat equation. Each line keeps its expression beside its result, so you can check any step, change it, and see the effect without starting over.

### Everyday math and percentages

Work out tips, discounts, splits, totals, ratios, and markups with expressions that read like the question in your head.

```calculio
245 * 15%
86 + 15%
250 - 30%
```

[See examples](https://calcul.io/examples/index.md)

### Unit conversion without the detour

Convert length, mass, temperature, area, volume, speed, digital data, and other supported units by naming the target unit.

```calculio
5 km to miles
180 lb to kg
3 cups to ml
```

[Read conversion help](https://calcul.io/instructions/conversions/index.md)

### Dates, times, and durations

Add days to a date, compare calendar intervals, and keep a time calculation readable instead of translating it into seconds first.

```calculio
today + 30 days
90 days ago
8 hours + 45 minutes
```

[Learn date math](https://calcul.io/instructions/time/index.md)

### Currencies, stocks, and crypto

Use supported currency codes, stock tickers, and cryptocurrency symbols in the same workspace as the rest of your budget or estimate.

```calculio
1 BTC to AAPL
0.5 BTC to USD
1 AAPL + 10 MSFT to USD
```

[See currency syntax](https://calcul.io/instructions/currency/index.md)

### Advanced math, functions, and constants

Go further with algebra, trigonometry, statistics, matrices, probability, complex numbers, built-in constants, and named variables.

```calculio
round(hypot(3, 4) * sin(pi / 2), 3)
derivative("x^3 + 2x", "x")
sqrt(-4)
```

[Browse the function reference](https://calcul.io/functions/index.md)

```calculio
net = 2400
vat = 19%
net + net * vat
```

## Change a line. The rest follows.

Most quick calculators hand you an answer and forget it. Calcul.io keeps every step beside the final number, so you can reuse a value further down and update it whenever the real-world detail changes.

1. 1
   **Write an expression.** Start with plain arithmetic or a supported function.
2. 2
   **Give a value a name.** Reuse a bill, rate, distance, or any other number further down.
3. 3
   **Share the whole calculation.** The URL keeps the lines together for a later check.

## Start from a calculation that works.

Pick a worked example, replace the sample values with your own, and keep the reference pages nearby for syntax when you need a closer look.

Worked example / budgeting

### [Plan a vacation across currencies.](https://calcul.io/examples/vacation/index.md)

Keep transport, lodging, food, and activities on separate lines, then convert and total the trip in a target currency.

[Portfolio example**Total mixed holdings with symbols and quantities**](https://calcul.io/examples/portfolio/index.md)

[Browser workflow**Calculate from the Chrome address bar**](https://calcul.io/examples/google-chrome-search/index.md)

[Reference / aggregates**Sum, average, min, max, median, and mode**](https://calcul.io/aggregate-functions/index.md)

[Reference / units**Browse supported conversion units**](https://calcul.io/instructions/units/index.md)

[How to use Calcul.io](https://calcul.io/instructions/index.md)

[Math function reference](https://calcul.io/functions/index.md)

[Math and scientific constants](https://calcul.io/constants/index.md)

[Calculator guides](https://calcul.io/blog/index.md)

**Is Calcul.io free to use?**

Yes. Calcul.io is free to use and does not require an account. It runs in a browser, so you can start with a blank calculation whenever you need it.

**What can I type into Calcul.io?**

You can enter arithmetic, percentages, variables, supported math functions, unit conversions, dates, currencies, and supported stock or cryptocurrency symbols. Start with a simple expression and build from there.

**Can I use more than one line?**

Yes. Lines run top to bottom, and each one keeps its result beside it. Name a value on one line and use it again below, or keep intermediate steps visible so you can check them.

**How do unit conversions work?**

Write a value with its source unit and name the target unit, such as `5 km to miles`. Calcul.io converts compatible units and keeps the expression editable.

**Can I calculate dates and times?**

Yes. Calcul.io supports date arithmetic, time calculations, and durations. Expressions such as `today + 30 days` keep the calendar operation readable.

**Can I share a calculation?**

Yes. Calcul.io stores the calculation lines in the page URL, so you can copy the link and reopen the same work later or send it to someone else.

[Open calculator](https://calcul.io/app/index.md)