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Money
- 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.
- How much to save each month Say what you want and when. We work out the monthly amount, and how much of it the return contributes instead of you.
- Rental yield calculator Gross yield is the number in the advert. Net yield, after costs and empty months, is the one you actually get.
- Rule of 72 calculator The mental shortcut everyone knows, next to the exact answer. And how much the shortcut is off by at your rate.
- 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.
- Loan amortisation schedule Every payment broken down. The interesting part is not the total, it is watching how long it takes before you are mostly paying off the debt.
- Early repayment: term or payment One lump sum, two ways to use it. Which saves more interest is not close, but the other one has its reasons.
- How much mortgage can I afford Two things limit you: what you can pay each month and what you have saved. We tell you which one is binding, because that decides what to do about it.
Home and energy
- 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.
- Standby power cost calculator The devices you never really switch off. Individually trivial, and together a line on your bill that nobody looks at.
- Is it worth replacing that appliance The efficient one costs more today and less every year. Whether that trade works out depends on numbers, and usually it is closer than the shop suggests.
- Paint calculator for a room Room dimensions, number of coats and the area of doors and windows. We give you litres, tins and cost.
- Floor tile calculator Room size and tile size. We give you tiles, boxes and cost, with the wastage that cuts and breakages actually need.
- Air conditioner size calculator A rule of thumb for what size unit to look for, adjusted for the things that actually change the answer.
Dates and time
- Days between two dates calculator Enter two dates and we tell you how many days lie between them, broken down into weeks, spare days and hours.
- Difference between two dates in years, months and days Rather than counting loose days, this gives you the difference the way you would say it out loud: "2 years, 3 months and 5 days".
- Working days between two dates Count only the real working days between two dates: weekends come out, and public holidays too if you want them to.
- Add or subtract days from a date Give me a date and how many days to add or subtract. Count every day, or working days only.
- 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.
- Work hours calculator With your start time, finish time and break, we work out the effective day and what it adds up to over a week, a month and a year.
- Week number of the year Which week of the year a date falls in, under ISO 8601, which is the standard businesses use and does not always match what you would guess.
Cars and travel
- Real fuel economy calculator Fuel put in and distance covered. That is all it takes to know what your car really does, rather than what the trip computer claims.
- Cost per unit of distance of your car Fuel is the part you notice and the smallest part of the bill. This adds the ones you do not: insurance, tax, servicing and, above all, depreciation.
- Compare the fuel cost of two cars Two cars, two consumption figures, two fuel prices. What the difference actually adds up to over the years you will keep it.
- Electric car charging cost What a charge costs and how far it takes you. Including the energy you pay for that never reaches the battery, which nobody mentions.
- 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.
- Split the cost of a trip The awkward conversation, settled with a number. Fuel, tolls and extras split between everyone, or everyone except the driver.
Sport
- Running pace calculator Give me any two of them and I give you the third, plus the split table to take to the race.
- Your equivalent time at another distance From one recent result we estimate what you could do at any other distance. And we tell you when not to trust it.
- Splits for your race Your target time shared out kilometre by kilometre. With the option to plan a negative split, which is how the good races get run.
- Heart rate training zones Your five training zones in beats per minute, and what each one is for. With the heart-rate-reserve method if you have your resting figure.
- Swimming pace calculator Your pace per 100 metres, which is how swimming is measured, plus your time per length and what you would do over other distances.
Percentages and maths
- Percentage calculator Enter a percentage and a number. Instead of making you pick an operation first, we give you all four answers at once.
- Percentage change calculator From one value to another, how much has it gone up or down in percent? And how many times one is of the other.
- Stacked discount calculator 50% and then an extra 20% is not 70%. Here you see the real final price and the single discount you are actually being given.
- VAT calculator Add VAT to a price, or strip it out of one that already includes it. With the net and tax split, which is what an invoice needs.
- What percentage one amount represents Two numbers, and we tell you what percentage the first is of the second. With the remainder and the ratio in plain language.
- Rule of three calculator Solve a direct or inverse proportion. We show the working, not only the result.
- Weighted average calculator Paste your values with their weights, one per line. We give you the weighted average, the simple one, and how much each item contributes.
- What grade do I need on the final Tell us what you have and how much it counts. We tell you what you need on the rest, and if it is already out of reach we say so plainly.