Are these calculator tools free?

Yes. No usage limits, no account, no ads.

Do these calculators need an internet connection?

Only to open or reload a page. Once a calculator's page has loaded, every calculation runs locally in JavaScript, so you can disconnect from Wi-Fi and keep using that calculator until you close or reload the tab or open another page. Each page needs the connection again when it opens, because the site installs no service worker.

How accurate are the unit conversions?

The conversion factors come from official SI and NIST definitions. Internally everything is computed in double-precision floating-point, which is accurate to about 15 significant digits. For everyday conversions the result is exact to as many digits as you would normally care about.

What does Round up per person do in the tip calculator?

It rounds each person's share up to the next whole amount, so a share of 23.60 becomes 24.00, and the extra goes to the tip. The tip total and the grand total shown update to match.

Does the byte converter use 1024 or 1000 as the base?

Both, one at a time. Choose Decimal (SI), where a megabyte (MB) is 1,000,000 bytes, or Binary (IEC), where a mebibyte (MiB) is 1,048,576 bytes. Switching keeps the same byte count, so you can compare the two conventions.

How does the discount calculator combine two discounts?

It applies each discount to the price left after the one before, so 20% and then 10% off leaves 72% of the original price, an effective 28% off rather than 30%. In stacked and double-discount modes it lists each step under the result.

Why is there no calculation history?

Keeping a history would mean writing your inputs to browser storage, and these calculators keep your inputs only in the open page. Copy the result to a note app if you need to keep it.

Free online calculator tools

A collection of everyday calculators that run in your browser. Split a bill and its tip between guests, work out percentages and percentage change, find the sale price after one or more discounts, calculate an exact age in years, months, and days, convert between metric and imperial units, and convert file sizes between bytes and gigabytes. Results update as you type.

Every calculation runs locally in JavaScript, and the numbers you enter are not sent to our servers. For dates, Unix timestamps, and time zones, see the time tools.

Read the complete calculator tools guide

Tip calculator

Calculate tip amount, total per person, and split a bill between up to 20 guests.

Unit converter

Convert length, weight, temperature, speed and volume between metric and imperial. Instant results.

Byte converter

Convert between bytes, KB, MB, GB and TB in both decimal (SI) and binary (IEC) units.

Percentage calculator

Calculate percentages three ways: X% of Y, X is what % of Y, and percentage change.

Age calculator

Calculate your exact age in years, months, and days from your date of birth. Includes birthday countdown and total days lived.

Discount calculator

Calculate sale price and savings from a percent-off discount. Handles single or stacked discounts.

Why these calculators run in your browser

A calculator is one of the smallest things a computer does. Converting 5 kilometres to miles is a single multiplication. Working out an exact age is a subtraction with calendar awareness. There is no engineering reason to send the numbers to a server, wait for a response, and pay the latency cost. The browser can do it in microseconds.

The inputs are also things that simply do not need to be uploaded for the math to work. A tip split, a percentage, a unit conversion all run in a few lines of JavaScript. There is no good reason for those few lines to live on a remote server.

In-browser calculators show the result as you type. All processing happens locally in your browser. Close the page and the site keeps no copy of what you entered.

How the calculators work

Each calculator is a small JavaScript function. The unit converter has a lookup table of SI and imperial conversion factors and converts through a base unit, with offset formulas for temperature. The byte converter handles both decimal (SI) and binary (IEC) units, and switching between them keeps the same byte count. The percentage calculator does the three classic percentage operations (X percent of Y, X is what percent of Y, percentage change between two values). The tip calculator multiplies the bill by the tip rate and divides the total by the number of guests. The discount calculator applies each discount to the running price in turn, and the age calculator counts whole calendar months, then days, from the date of birth to today.

All math runs in JavaScript's 64-bit floating-point, which gives about 15 significant digits of precision. That is more than enough for any unit conversion or percentage you would do without a spreadsheet.

In-browser calculators vs the alternatives

Approach	Privacy	Cost	Best for
In-browser (this site)	Processed locally	Free	One-off lookups, ad-hoc questions
Search engine quick conversions	Query sent to the search provider	Free	Quick conversions when search is already open
Spreadsheet applications	All local, or synced if stored in the cloud	Free to paid	Repeated calculations on many rows

For a single conversion or a quick percentage, a dedicated in-browser tool is faster than typing into a search bar and waiting for the answer card. For repeated calculations on many values, a spreadsheet is the right answer.

When to use these tools

Working with everyday measurements? Switch metric and imperial values with the unit converter, or work out file sizes between bytes and gigabytes using the byte converter.
Splitting a restaurant bill with friends? The tip and split calculator handles gratuity per person, and the discount calculator finds the sale price after a percent-off promotion.
Doing percentage math for a school assignment or budget? The percentage calculator covers the three common operations (X percent of Y, what percent X is of Y, and change between two values).
Marking a milestone? Work out your exact age in years, months, and days with the age calculator.

Frequently asked questions

Are these calculator tools free?: Yes. No usage limits, no account, no ads.
Do these calculators need an internet connection?: Only to open or reload a page. Once a calculator's page has loaded, every calculation runs locally in JavaScript, so you can disconnect from Wi-Fi and keep using that calculator until you close or reload the tab or open another page. Each page needs the connection again when it opens, because the site installs no service worker.
How accurate are the unit conversions?: The conversion factors come from official SI and NIST definitions. Internally everything is computed in double-precision floating-point, which is accurate to about 15 significant digits. For everyday conversions the result is exact to as many digits as you would normally care about.
What does Round up per person do in the tip calculator?: It rounds each person's share up to the next whole amount, so a share of 23.60 becomes 24.00, and the extra goes to the tip. The tip total and the grand total shown update to match.
Does the byte converter use 1024 or 1000 as the base?: Both, one at a time. Choose Decimal (SI), where a megabyte (MB) is 1,000,000 bytes, or Binary (IEC), where a mebibyte (MiB) is 1,048,576 bytes. Switching keeps the same byte count, so you can compare the two conventions.
How does the discount calculator combine two discounts?: It applies each discount to the price left after the one before, so 20% and then 10% off leaves 72% of the original price, an effective 28% off rather than 30%. In stacked and double-discount modes it lists each step under the result.
Why is there no calculation history?: Keeping a history would mean writing your inputs to browser storage, and these calculators keep your inputs only in the open page. Copy the result to a note app if you need to keep it.