9 free tools · run in your browser
Everyday tools and calculators
Free, quick answers for the questions that come up every day: how many days until a date, what time it is for a colleague abroad, how many pounds are in 5 kilograms, or what your GPA is now.
Everyday tools
- Age calculatorWork out an exact age, the days or business days between two dates with US, UK, Canadian or Australian public holidays, and add or subtract time.
- Time zone converterConvert a date and time between IANA zones with daylight-saving rules.
- Time zone meeting plannerPick several cities and see their working hours side by side to find meeting times that suit everyone, with daylight saving handled.
- Unit converterConvert length, weight, temperature, volume, data and more between metric, imperial and US units.
- Random name pickerShuffle a list, pick random names with a spinning wheel, or split people into balanced teams.
- GPA calculatorCalculate semester and cumulative GPA, weighted or unweighted, with letter grade and percentage conversion.
- Pomodoro timerFocus with work sessions, short breaks and long breaks, with optional notifications.
- PPI calculatorCalculate pixel density, physical dimensions and compare two displays.
- Send text from PC to phoneSend text, links, GUIDs, JSON and small files between a PC and a phone with a temporary code — encrypted in your browser, received once.
Pick the right tool
- Exact age, days between two dates, or business days with US, UK, Canadian or Australian holidays: Age & Date Calculator.
- What time a given moment is somewhere else: Time Zone Converter.
- A meeting slot that suits people in several cities: Time Zone Meeting Planner.
- Length, weight, temperature, volume, data and more: Unit Converter.
- Semester or cumulative GPA, weighted or unweighted: GPA Calculator.
- Draw a name, spin a wheel or split a group into teams: List Randomizer.
- Focus in timed sessions with breaks: Pomodoro Timer.
- Compare screen sharpness before buying a monitor: PPI Calculator.
- Move a link or small file from your PC to your phone: Northlane Transfer.
Private by default
The calculators and converters run in your browser. Dates, names and grades you enter aren't uploaded or stored, and there's no account to create. Northlane Transfer is the one tool that uses a server, because it has to pass data between two devices: the content is encrypted in your browser before it's sent, held temporarily under a short code, and can be received once.
Time zones, done properly
Time zone mistakes usually come from fixed offsets: assuming New York is always five hours behind London, for example. It isn't. The US and Europe change their clocks on different dates, so for a week or two each spring and fall the gap is four hours. The converter and meeting planner use the IANA time zone database built into your browser and work out the offset for the exact date you choose, including half-hour zones like India and 45-minute zones like Nepal.
For a step-by-step method and overlap tables for common city pairs, read how to find the best meeting time across time zones.
Guides
Frequently asked questions
Are these tools free to use?+
Yes. All of them are free, with no sign-up and no limit on how often you use them.
Does the date calculator count the end date?+
You can choose. Counting from one date to the next normally excludes the start day; an option lets you include both ends, which is how many people count days of a trip or a notice period.
How does the meeting planner handle daylight saving time?+
It calculates every local time from the actual date, so a meeting planned for next March reflects the clock changes that will have happened by then, even if they differ between countries.
What's the difference between weighted and unweighted GPA?+
Unweighted GPA uses a 4.0 scale for every class. Weighted GPA adds extra points for honors, AP or IB courses, so it can go above 4.0. Colleges often look at both.
Is the list randomizer truly random?+
It draws from your browser's cryptographic random number generator, which is fine for picking names, raffles in class or splitting teams. It isn't meant for regulated draws or lotteries.
How big a file can I send with Northlane Transfer?+
A transfer can carry up to 10 MB in total, which suits text, links, documents and photos rather than large media. For big videos or folders, use a cloud storage link instead.
Do the tools work on my phone?+
Yes. Every page is built to work on a phone browser as well as a desktop, with no app to install.