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See allCompound Interest
See how savings grow with monthly contributions and compounding — future value, total contributed and interest earned.
Tip & Bill Split
Split any restaurant bill — tip amount, total and what each person pays.
Mortgage Calculator
Estimate your monthly mortgage payment, total interest and lifetime cost. Adjust the loan, term and rate — every figure updates as you type.
BMI Calculator
Your body mass index from height and weight, with the healthy weight range for your height.
Concrete Slab
Volume, number of 25 kg bags and cost for a slab — just enter length, width and thickness.
Miles to Kilometres
Convert miles to kilometres, metres and feet instantly.
Freelance Day Rate
Work out the day rate you need from your target take-home, business costs and billable days.
GPA Calculator
Your grade point average on the 4.0 scale — add each course with its credits and letter grade, and the GPA, total credits and quality points update as you type.
New & Notable
See allProjector Screen Illuminance Comparison
Compare the average screen illuminance from the same projector at two image sizes. Keep the aspect ratio, picture mode and surface fixed for the comparison.
VAT Calculator
Add VAT to a net amount or take it back out of a gross one — the VAT, the net and the gross together, at the standard, reduced, zero or any custom rate.
Bolt Pattern Force Distribution
The elastic-method load on every bolt of an in-plane pattern under an eccentric force — centroid, direct shear and the critical bolt's load, straight from the bolt coordinates.
Invoice & Quote Total
Add line items with quantity and unit price — each amount, the net subtotal, tax and the invoice total update as you type. Apply an overall discount for quotes.
Stress–Strain Curve
Approximate a material's engineering stress–strain curve with the Ramberg–Osgood equation — strain hardening exponent, yield and failure strains, and the full interactive curve from four material properties.
GPA Calculator
Your grade point average on the 4.0 scale — add each course with its credits and letter grade, and the GPA, total credits and quality points update as you type.
Miles to Kilometres
Convert miles to kilometres, metres and feet instantly.
Profit Margin
Margin, profit per unit and markup from a selling price and unit cost.
Staff Picks
See allCompound Interest
See how savings grow with monthly contributions and compounding — future value, total contributed and interest earned.
Mortgage Calculator
Estimate your monthly mortgage payment, total interest and lifetime cost. Adjust the loan, term and rate — every figure updates as you type.
BMI Calculator
Your body mass index from height and weight, with the healthy weight range for your height.
Concrete Slab
Volume, number of 25 kg bags and cost for a slab — just enter length, width and thickness.
GPA Calculator
Your grade point average on the 4.0 scale — add each course with its credits and letter grade, and the GPA, total credits and quality points update as you type.
Profit Margin
Margin, profit per unit and markup from a selling price and unit cost.
VAT Calculator
Add VAT to a net amount or take it back out of a gross one — the VAT, the net and the gross together, at the standard, reduced, zero or any custom rate.
Invoice & Quote Total
Add line items with quantity and unit price — each amount, the net subtotal, tax and the invoice total update as you type. Apply an overall discount for quotes.