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Pythagoras
Pythagoras is a collection of calculators I often use myself. From compound interest to your billable days as an interim professional. Timeless calculations, clearly presented, without noise. Free to use, no account needed.
Wat zit erin
Eleven calculators, one page.
A set of timeless calculators: compound interest, annuity, freelance rate, billable days and more. Ready to use, with charts and overviews.
Personal
Compound interest
Calculate how your wealth grows with compound interest. You see straight away how your contributions and the compounded return add up together, with a chart and an annual overview.
Annuity / monthly loan payment
Calculate the monthly payment on a loan or mortgage, annuity-based or linear. If you have a mortgage that's partly annuity-based and partly linear, you calculate both parts together, each with its own interest rate. With a full repayment schedule and remaining-debt trajectory.
Saving towards a goal
Know how much you want to have, but not how much you need to put in? Enter your savings goal, term and expected return and calculate how much you need to set aside each month to reach that goal.
Inflation / purchasing power
See what your money will still be worth in a number of years. Enter an amount, an expected inflation rate and a number of years and calculate the future purchasing power.
Doubling time (rule of 72)
How quickly does your money double? The rule of 72 gives you a quick indication: divide 72 by your annual return and you'll know roughly after how many years your contribution has doubled.
Business
Rate converter
Quickly convert between hourly, daily, weekly, monthly and annual rates. Enter your hours per week and working weeks per year. Handy for freelancers and clients who want to express a rate in a different time frame.
Freelance hourly rate
Calculate the hourly rate you need to charge as a freelancer or interim professional. Enter your desired annual income, your billable hours and your annual costs and see what hourly rate that requires.
Billable days
Calculate how many days you're actually billable this year. Choose a year and the tool shows the working days and the official Dutch public holidays that fall on a working day.
Project ROI / payback time
Calculate the return on an investment or project. Enter the one-off investment and the annual net saving or revenue and see the ROI and the payback time.
General
VAT
Easily add or remove VAT. Enter an amount, choose the VAT rate and see the amount including and excluding VAT, plus the VAT amount itself.
Percentage
A handy calculator for percentages. Calculate what percentage one is of another, a percentage of an amount, or the percentage increase or decrease between two numbers.
Do the maths yourself.
Open the calculator and work out your own figures straight away. Free to use, no account needed.
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