About Binary Decimal
Free calculators and tools that give a clear answer, show their working, and keep your data on your device.
- Health & fitness
- Money
- Maths & school
- Write & create
- Developer
- Time & focus
- free tools
- 57
- free tools
- groups
- 6
- groups
- sign-ups needed
- 0
- sign-ups needed
- calculations run in your browser
- Local
- calculations run in your browser
At Binary Decimal, we’re passionate about making calculations easier and more accessible for everyone. We build free online calculators and tools that take a complex task — converting between number systems, planning a mortgage, reading a lab result — and give you a clear answer in plain words.
Whether you’re a student tackling homework, a professional streamlining your workflow, or simply curious about the world of numbers, the right tool should be fast, honest about what it knows, and pleasant to use.
What we build
57 tools in 6 groups. Most open with a worked example, so you see an answer before you type anything.
Health & fitness
11 toolsTraining plans, trackers and percentiles built on clinical data.
Money
6 toolsMortgages, loans, savings and big purchases, with honest verdicts.
Maths & school
12 toolsAnswers with the working shown, for homework and grades.
Write & create
9 toolsBoards, notes, diagrams and colour, saved in your browser.
Developer
12 toolsQuick utilities and capacity maths for engineers.
Time & focus
7 toolsTimers that keep exact time, and dates worked out to the day.
Where the numbers come from
The maths is standard, and most tools show how the answer was worked out. When a tool compares you with other people or turns one measurement into another, it uses published research and names it, so you can check it:
- Glucose ↔ A1Cthe ADAG study formula (Nathan et al., 2008)
- Kids growthWHO growth standards to age 2, CDC growth charts from 2 to 20
- GLP-1 weight lossthe STEP-1 and SURMOUNT-1 trial results
- Penis size percentileVeale et al. (2015), 15,521 men measured by clinicians
Health tools give information, not a diagnosis. If something on the site is wrong, we want to know and we fix it.
Privacy: it runs in your browser
- Calculations happen on your device. What you type into a calculator isn’t sent to us.
- Your work stays in this browser. Notes, Markdown and Mermaid documents, vision boards and workout progress are saved locally, with no account.
- We count visits, not you. Google Analytics tells us which pages and features are used so we know what to improve; it never sees the numbers you enter.
The details are in our Privacy Policy and Terms of Use. Questions, bugs or ideas: use the contact form.
Keep it free
Binary Decimal has no paywall and no sign-up, and it costs money to run. If a tool saved you time or helped you understand something, a coffee is a lovely way to say thanks and keeps new tools coming.
Buy me a coffeeStart with a popular tool
Base converterMortgage calculatorWorkout plan generatorRead the blog