67 tools · no sign-up · no ads
Calculators that get to the point
Solve one specific thing and get on with your day. Always showing where each figure comes from and what has been assumed.
- 67tools
- 38with a chart
- 9topics
- 100 %in your browser
What you used last
Start here
Six of the most looked-for, one from each topic.
- Loan payment calculator Work out the monthly payment on a loan or mortgage and, above all, how much you will end up paying in interest. Money
- Exact age calculator Enter a date of birth and we work out the exact age in years, months and days, plus how long is left until the next birthday. Dates
- Percentage calculator Enter a percentage and a number. Instead of making you pick an operation first, we give you all four answers at once. Percentages
- What a trip costs in fuel Distance, consumption and fuel price. What the trip really costs, tolls included, and whether the train was cheaper after all. Cars
- Appliance running cost calculator Power rating, hours of use and your electricity price. That is enough to know what any appliance is really costing you. Home
- Running pace calculator Give me any two of them and I give you the third, plus the split table to take to the race. Sport
- JSON formatter and validator Paste the JSON, pick an indent, done. If something is off we tell you exactly where, and how many keys and how deep it goes. Code
- Compound interest calculator Work out how much your savings will grow with compound interest and regular contributions, and how much of that total came from interest rather than from you. Money
- Base64 encoder and decoder Text to Base64 and back again. With real UTF-8, which is where half the home-made implementations fall over. Code
Just added
The most recent to go up.
- Simple interest calculator Simple interest always pays on the original capital and never on what you have already earned. Here it sits next to compound, which is where the difference shows.
- CAGR calculator Two figures and a term give the constant rate that would have taken the first to the second. It is the honest way to compare investments of different lengths.
- ROI calculator ROI is a simple division that gets misused constantly: 50% in six months and 50% in ten years give the same figure. So here it comes annualised too.
- What day of the week a date falls on What day you were born on, what day your birthday falls on, when a deadline lands. With the week number and the days between it and today.
- Fraction calculator The four operations on fractions, simplified at the end and with the intermediate step visible, which is where you see why the answer is what it is.
- Greatest common factor and lowest common multiple Both at once, for as many numbers as you like, with each one broken into primes alongside. Which is where you see why the answers are what they are.
The six topics
Every tool lives inside one of them.
- Money 13 Compound interest, loans, mortgages and savings goals, with a breakdown of where every figure comes from and a chart of how it evolves. See all 13 tools
- Home and energy 6 What your appliances cost to run, what standby really adds up to, and how much material a room actually needs. See all 6 tools
- Dates and time 8 Days between dates, ages, working days, deadlines and hours worked. Instant results, no sign-up. See all 8 tools
- Cars and travel 6 Real fuel economy, what a trip costs, cost per mile and splitting the bill between everyone in the car. See all 6 tools
- Sport 5 Running paces, race-time equivalents, splits and training zones. For running with your head as well as your legs. See all 5 tools
- Health and body 4 Body mass index, healthy weight, body fat and daily calories, with the formula in plain sight and what each number leaves out. See all 4 tools
- Percentages and maths 10 Discounts, increases, proportions, VAT, averages and grades. Everyday maths, properly explained. See all 10 tools
- Business and pricing 5 Margin, markup, commission, asset depreciation and what a campaign costs. The sums you do before setting a price. See all 5 tools
- Developers 10 Format JSON, encode and decode, convert bases and colours. The things you look up mid-afternoon with the editor open. See all 10 tools
Missing one?
The ones here came from real problems. If yours is not, tell us: it is the best clue about what to build next.