The garden almanac of useful numbers
A garden of calculators that just work.
Plant a number, harvest an answer. Every calculator in the catalogue lands with sensible defaults, shows the formula behind the result, and runs entirely in your browser. No sign-up, no clutter, new plots sown every week.
79 calculators6 garden beds0 sign-ups needed
Money & Finance
View all →UK Salary Take-Home Calculator
Estimate your monthly take-home from a UK gross salary using simplified 2025 tax bands.
Open calculatorPlot No. 2Mortgage Repayment Calculator
See your monthly mortgage payment and total interest over the life of the loan.
Open calculatorPlot No. 3FIRE Retirement Calculator
Find out when you can retire based on savings, monthly investing and target spend.
Open calculatorPlot No. 4Loan Amortization Calculator
Year-by-year breakdown of principal and interest for any fixed-rate loan.
Open calculatorPlot No. 8Compound Interest Calculator
See how a lump sum grows over time with compounding using the A=P(1+r/n)^nt formula.
Open calculatorPlot No. 11Savings Goal Calculator
Work out how long it takes to reach a savings target from your balance and monthly deposits.
Open calculatorPlot No. 13Hourly to Salary Calculator
Convert an hourly wage into annual, monthly and weekly gross pay in seconds.
Open calculatorPlot No. 16Inflation Calculator
See the future value of money and cumulative price rise from an inflation rate over time.
Open calculatorPlot No. 19Break-Even Calculator
Find the units and revenue needed to cover fixed costs from your price and cost per unit.
Open calculatorPlot No. 20Car Loan Calculator
Monthly payment, total interest and total cost on a car loan from price, deposit, APR and term.
Open calculatorPlot No. 21Credit Card Payoff Calculator
See how many months to clear a card balance at a fixed monthly payment, plus total interest.
Open calculatorPlot No. 22Simple Interest Calculator
Interest and final balance using interest equals principal times rate times time. Does not compound.
Open calculatorPlot No. 23ROI Calculator
Total ROI percent, net profit and annualised ROI from amount invested, final value and years held.
Open calculatorPlot No. 24CAGR Calculator
Compound annual growth rate and total growth from a beginning value, ending value and years.
Open calculatorPlot No. 25Rule of 72 Calculator
Estimate years to double money by dividing 72 by the rate, with the exact doubling time too.
Open calculatorPlot No. 26Net Worth Calculator
Add your assets and subtract your debts to see your true net worth in pounds.
Open calculatorPlot No. 27Debt-to-Income Ratio Calculator
Divide monthly debt by gross monthly income to see your DTI percentage and band.
Open calculatorPlot No. 28Emergency Fund Calculator
See your target emergency fund, the shortfall and how many months you already cover.
Open calculatorPlot No. 29Mortgage Affordability Calculator
Estimate your maximum mortgage and property price from income, multiple and deposit.
Open calculatorPlot No. 30Down Payment Calculator
Turn a property price and deposit percentage into your deposit, mortgage and LTV.
Open calculatorPlot No. 31Rent vs Buy Calculator
Compare the net cost of renting and buying over your time horizon to see which wins.
Open calculatorPlot No. 70Life Insurance Needs Calculator
Work out how much life cover you need from debts, income replacement, education costs and existing savings or insurance.
Open calculatorPlot No. 72Crypto DCA Calculator
See how a regular dollar-cost averaging contribution could grow, with total invested, projected value and profit.
Open calculatorPlot No. 78Student Loan Repayment Calculator (UK)
Estimate your monthly UK student loan repayment from your salary and Plan 1, 2, 4, 5 or Postgraduate plan.
Open calculatorPlot No. 79US Paycheck Tax Calculator
Estimate US take-home pay from gross salary using simplified federal tax brackets, FICA and a state tax rate.
Open calculatorEveryday & Shopping
View all →Tip & Bill Split Calculator
Quickly figure the tip, total bill and per-person share for any group.
Open calculatorPlot No. 7Percentage Calculator
Find a percentage of any number and see it added on or taken off, for discounts and tips.
Open calculatorPlot No. 9Age Calculator
Find your exact age in years, months and days, plus total days and weeks lived.
Open calculatorPlot No. 10VAT Calculator
Add VAT to a net price or remove VAT from a gross price at any rate in seconds.
Open calculatorPlot No. 12Discount Calculator
Find the sale price and how much you save from an original price and discount percentage.
Open calculatorPlot No. 17Fuel Cost Calculator
Estimate the fuel cost of any car journey from distance, mpg and the price per litre.
Open calculatorPlot No. 18Electricity Cost Calculator
Work out an appliance's running cost per day, month and year from watts and your kWh rate.
Open calculatorPlot No. 32Sales Tax Calculator
Add US sales tax to any price to see the tax owed and your total at the register.
Open calculatorPlot No. 33Gas Mileage (MPG) Calculator
Work out your car's MPG from miles driven and gallons used, with metric equivalents.
Open calculatorPlot No. 34Unit Price Comparison Calculator
Compare two products by price per unit to see which is genuinely cheaper.
Open calculatorPlot No. 35Cooking Measurement Converter
Convert recipe volumes between ml, tsp, tbsp, fl oz, cups, pints and litres.
Open calculatorPlot No. 36Pizza Size Value Calculator
Compare two pizzas by price per square inch to find the better deal.
Open calculatorPlot No. 37Time Duration Calculator
Find the gap between two clock times in hours and minutes, total minutes and decimal hours.
Open calculatorPlot No. 38Days Between Dates Calculator
Count the days, weeks and approximate months between any two calendar dates.
Open calculatorPlot No. 39Days Until a Date Calculator
Count down the days until a future date, or count up the days since a past one.
Open calculatorPlot No. 40Hours Calculator
Turn clock in and clock out times into paid hours and gross shift pay.
Open calculatorPlot No. 41Roman Numeral Converter
Convert numbers from 1 to 3999 into Roman numerals and decode numerals back to numbers.
Open calculatorPlot No. 71Currency Converter (Indicative Rates)
Convert between major currencies using a fixed, manually set rate table for rough budgeting. Not live rates.
Open calculatorPlot No. 73Subscription Cost Calculator
Add up streaming, music, software, gym and other subscriptions to see monthly, annual and 5-year totals.
Open calculatorPlot No. 74Wedding Budget Calculator
Split a total wedding budget across venue, catering, attire and more using typical percentage shares.
Open calculatorPlot No. 75Moving Cost Calculator
Estimate a house move's cost from movers, truck rental, packing materials and a long-distance surcharge.
Open calculatorHealth & Fitness
View all →BMI Calculator
Work out your body mass index from your height and weight, and see your weight category.
Open calculatorPlot No. 14BMR and Calorie Calculator
Estimate your daily maintenance calories with the Mifflin-St Jeor BMR and activity level.
Open calculatorPlot No. 42Body Fat Percentage Calculator
Estimate body fat percent from height, neck and waist using the US Navy tape method.
Open calculatorPlot No. 43Ideal Weight Calculator
Find a target weight for your height with the Devine formula plus a healthy BMI range.
Open calculatorPlot No. 44Waist-to-Height Ratio Calculator
Divide waist by height to screen for central fat. Keep your waist under half your height.
Open calculatorPlot No. 45Macronutrient Calculator
Split a daily calorie target into protein, carb and fat grams by your chosen ratio.
Open calculatorPlot No. 46Daily Protein Intake Calculator
Set a daily protein target from your body weight and activity goal, with a working range.
Open calculatorPlot No. 47Daily Water Intake Calculator
Estimate daily fluid from body weight and exercise, in litres and 250 ml glasses.
Open calculatorPlot No. 48Calories Burned Calculator
Estimate calories burned during exercise from activity, body weight and duration using MET values.
Open calculatorPlot No. 49Target Heart Rate Zone Calculator
Find your max heart rate and fat-burn, cardio and peak training zones from your age.
Open calculatorPlot No. 50Running Pace Calculator
Turn a run distance and finish time into pace per km, pace per mile and average speed.
Open calculatorPlot No. 51One-Rep Max (1RM) Calculator
Estimate your one-rep max from weight and reps with the Epley formula, plus training loads.
Open calculatorPlot No. 52Pregnancy Due Date Calculator
Estimate your due date with Naegele's rule and see your current pregnancy week and trimester.
Open calculatorPlot No. 53Sleep Cycle Calculator
Find the best times to sleep or wake based on 90-minute sleep cycles.
Open calculatorEducation
View all →GPA Calculator
Calculate your weighted GPA on the 4.0 scale from each course's credits and letter grade.
Open calculatorPlot No. 54Final Grade Calculator
Find the score you need on your final exam to reach the overall grade you want.
Open calculatorPlot No. 55Grade Calculator
Convert points earned out of points possible into a percentage and letter grade.
Open calculatorPlot No. 56Average Calculator
Find the mean, median, mode, range, sum, count, min and max of a list of numbers.
Open calculatorPlot No. 57Ratio Calculator
Simplify a ratio to its lowest terms and solve a proportion A:B = C:x for the missing value.
Open calculatorPlot No. 58Fraction Calculator
Add, subtract, multiply or divide two fractions and get the answer in lowest terms plus a decimal.
Open calculatorPlot No. 59Standard Deviation Calculator
Get the mean, variance and both population and sample standard deviation from a list of numbers.
Open calculatorPlot No. 60Circle Calculator
Find a circle's area, circumference and diameter from its radius or diameter.
Open calculatorPlot No. 61Pythagorean Theorem Calculator
Find the hypotenuse or a missing leg of a right triangle using a squared plus b squared equals c squared.
Open calculatorHome & Garden
View all →Paint Calculator
Work out litres of paint and 2.5 litre tins from room size, coats and coverage.
Open calculatorPlot No. 63Tile Calculator
Find how many tiles to buy from the area and tile size, including a waste allowance.
Open calculatorPlot No. 64Concrete Calculator
Estimate concrete volume and 25 kg bags for a slab, with a 10 percent waste buffer.
Open calculatorPlot No. 65Mulch Calculator
Convert bed size and depth into mulch volume, litres, 50 litre bags and cubic yards.
Open calculatorPlot No. 66Raised Bed Soil Calculator
Work out the soil to fill a raised bed in cubic metres, litres and 50 litre bags.
Open calculatorPlot No. 67Gravel Calculator
Estimate gravel by tonnes and bulk bags from area, depth and stone density.
Open calculatorBusiness & Work
View all →Profit Margin Calculator
Turn cost and sale price into profit, profit margin percent and markup percent.
Open calculatorPlot No. 69Markup Calculator
Set a sale price from a cost and markup percent, with profit and resulting margin.
Open calculatorPlot No. 76Freelance Day Rate Calculator
Turn a target income into the day rate and hourly rate to charge, accounting for overheads and non-billable time.
Open calculatorPlot No. 77Sales Commission Calculator
Work out commission earned and total pay from base salary, sales, commission rate and quota.
Open calculatorFrom the potting shed
New calculators every week
We sow tools across personal finance, everyday maths, health and education on a regular cadence, and write a plain-English guide for the ones that need explaining. Browse the guides to see the maths behind the numbers, or bookmark the site and check back for what is new.