calculator1calculator
Official starter calculators from the 1calculator team.
Calculators (34)
Compound 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.
Profit Margin
Margin, profit per unit and markup from a selling price and unit cost.
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.
Percentage Calculator
What is X% of a number — type the percentage and the amount.
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.
Discount Calculator
The final price after a percentage discount.
Fuel Cost
What a trip costs in fuel, from distance, consumption and fuel price.
Decimal Hours
Convert hours and minutes into decimal hours for timesheets.
Final Grade Needed
The score you need on the final exam to end up with your target grade.
Running Pace
Your pace per kilometre from distance and finish time.
Dog Years
Your dog's age in human years (the classic ×7 rule of thumb).
Percentage Change
The percentage increase or decrease between two values.
Price per m²
Compare homes fairly — purchase price divided by living area.
Average Speed
Average speed from distance travelled and time taken.
Paint Needed
Litres of paint for a wall or room, from area and coverage.
Daily Travel Budget
How much you can spend per day from your total trip budget.
Ohm's Law
Current from voltage and resistance (I = V / R).
Rule of Three
Solve proportions: if A gives B, what does C give?
XP per Hour
Your grind rate — experience earned divided by hours played.
Driving CO₂
The CO₂ emitted by a car trip, from distance and an emission factor.
Daily Milk Intake
A newborn's typical daily formula amount from body weight (about 150 ml per kg).
Molarity
The molar concentration of a solution from moles and volume.
BPM to Milliseconds
Milliseconds per beat from a tempo — for delays and LFO sync.
Clip Duration
How long a clip runs, from its frame count and frame rate.
Plants per Row
How many plants fit in a row, from its length and plant spacing.
Cell Density
Cells per millilitre from a count and sample volume.