Calculator Tools
Quick calculators for everyday questions: dates, working days and hours, pay, percentages, statistics and school maths, prices, tax and margins, fuel and electricity, savings, ROI, depreciation and loans, GPA, and health and fitness. Results update as you type.
Real-Time Calculations
Outputs recalculate instantaneously as you enter numbers and dates
Standard Formulas
Formulas tested for leap years, month ends and rounding
Strictly Private
Financial, loan, and health metrics are never logged or stored
Formula Transparency
Every formula, rule, and worked example is openly documented
Loans, savings and investments
5 toolsShopping and business
7 toolsHome and travel
2 toolsMaths
9 toolsEducation
1 toolWork and pay
1 toolDates and time
4 toolsHealth and fitness
4 toolsDecision Guidance
Which calculator should I use?
Task to Tool Directory (38 jobs)
Scroll horizontally on mobile| What you need to do | Recommended Tool |
|---|---|
| How old someone is today or on a set date | Age Calculator |
| Days left until a birthday | Age Calculator |
| Days, weeks or months between two dates | Date Difference Calculator |
| Working days between two dates, without weekends or holidays | Business Days Calculator |
| A deadline a number of working days away | Business Days Calculator |
| A sale price or saving after a discount | Discount Calculator |
| A percentage of an amount | Percentage Calculator |
| Which pack size is cheaper per kg, litre or item | Unit Price Calculator |
| How savings grow with compound interest and monthly deposits | Compound Interest Calculator |
| Interest on a loan or deposit without compounding | Simple Interest Calculator |
| How many units to sell to cover your costs | Break-Even Calculator |
| Add GST or VAT to a price, or take it out | Tax Calculator |
| Simplify a ratio or scale a recipe | Ratio Calculator |
| Add or divide fractions | Fraction Calculator |
| The monthly payment on a home, car or personal loan | EMI Calculator |
| Adult BMI from weight and height | BMI Calculator |
| Hours worked between two times | Time Duration Calculator |
| A week’s hours from several shifts, and the pay for them | Time Duration Calculator |
| Take-home pay after tax and deductions, or an hourly wage as a yearly salary | Salary Calculator |
| How much sooner a loan ends with an extra monthly payment | EMI Calculator |
| The date 90 days, 6 weeks or 3 months from a date | Date Difference Calculator |
| The score you need on a final exam | Weighted Average Calculator |
| The average of test scores, prices or times | Average Calculator |
| Profit margin or markup on a sale | Profit Margin Calculator |
| The return on an investment, overall and per year | ROI Calculator |
| How long a savings goal takes, or how much to save each month | Savings Goal Calculator |
| The fuel cost of a trip or commute, a passenger’s share, or two cars compared | Fuel Cost Calculator |
| A GPA or CGPA from grades and credits | GPA Calculator |
| A course grade from assignments worth different percentages | Weighted Average Calculator |
| Estimated calories your body uses at rest (BMR) | BMR Calculator |
| A sales commission at a percentage rate | Percentage Calculator |
| Your running pace or a race finish time | Pace Calculator |
| What an appliance costs to run | Electricity Cost Calculator |
| An electricity bill from two meter readings | Electricity Cost Calculator |
| An asset’s yearly depreciation and book value | Depreciation Calculator |
| Estimated body fat from tape measurements | Body Fat Calculator |
| A test score as a percentage | Percentage Calculator |
| Growth or decline between two values | Percentage Calculator |
Frequently Asked Questions
Why don’t percentages simply add or subtract?
Because each percentage is taken of a different amount. Discounts of 20% and then 10% give 28% off, because the second applies to the reduced price. A 25% rise followed by a 20% fall brings you back to the start. And tax included in a price can’t be removed by subtracting the rate: 118 including 18% tax is 100 before tax, not 96.76. The Discount, Percentage and Tax calculators each handle one of these.
Do the date calculators handle leap years?
Yes. The Age, Date Difference and Business Days calculators all use calendar arithmetic, so 29 February and the different lengths of months are counted correctly.
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