Date and time calculators
Days, dates, ages and work hours, worked out in your browser
Pick a task below. Every calculator runs in your browser, opens with a worked example, and explains how the answer is reached. No sign-up and nothing you type is sent anywhere.
Dates and days
Count the days between dates, move a date forward or back, and work out ages.
Days between dates
Count days, weeks and months from one date to another.
Add or subtract days
Find the date a number of days, weeks or months from now.
Working days between dates
Count Monday to Friday days and leave out dates you choose.
Age calculator
Exact age from a date of birth, plus the next birthday.
Hours and work time
Add up hours for a shift, a week or a list of durations.
Grades and school
Turn scores into grades, work out a GPA, see what you need on the final, and more.
Grade calculator
Test score to percentage and letter, with a grading chart.
Weighted grade calculator
Class grade from parts that count different amounts.
Final grade calculator
The score you need on the final for the grade you want.
GPA calculator
GPA on the 4.0 scale, unweighted and weighted.
CGPA to percentage
CGPA to percentage with CBSE's 9.5 formula, and back.
Attendance calculator
Attendance percent, and classes needed for 75%.
UCAS points calculator
UCAS Tariff points for A levels, EPQ and Scottish Highers.
Molecular weight calculator
Molar mass from a formula, with brackets and hydrates.
Area and volume
Square feet and square metres, shapes, land and cubic volume.
Square footage calculator
Square feet and square metres of rooms, L-shapes and odd shapes.
Area calculator
Area of rectangles, triangles, circles and more, in any unit.
Volume calculator
Volume of boxes, cylinders and other shapes, in cubic feet, yards or metres.
Acreage calculator
Acres and hectares of a plot from its measurements.
Concrete, bricks and landscaping
How much concrete, block, brick, gravel, mulch or soil to order.
Concrete calculator
Cubic yards, cubic metres and bags for slabs, footings, holes and steps.
Brick and block calculator
Bricks or concrete (cinder) blocks for a wall, any size.
Gravel calculator
Cubic yards and tons of gravel, stone or sand for an area.
Mulch calculator
Cubic yards and bags of mulch or bark for a garden bed.
Topsoil calculator
Cubic yards and bags of topsoil for a lawn or raised bed.
Paint, tiles, flooring and drywall
Cover walls and floors, with the allowance for cuts shown.
Paint calculator
Gallons or litres of paint for a room, with doors and windows taken off.
Tile calculator
How many tiles and boxes, with grout gaps and cutting waste.
Flooring calculator
Boxes of laminate, vinyl or wood flooring, with cutting waste.
Drywall calculator
Sheets of drywall or plasterboard for walls and ceilings.
Roofs, stairs and heating
Roof area and pitch, stair rise and run, and room heating or cooling size.
Roofing calculator
Roof area, roofing squares and shingle bundles from footprint and pitch.
Roof pitch calculator
Roof pitch from rise and run, as x in 12, degrees and percent.
Stair calculator
Number of steps, riser height and total run for a straight stair.
BTU calculator
Heat output for a room in watts and BTU, or an air conditioner size.
Percentages
Percent of a number, percentage change, and adding or taking off a percentage.
Math and numbers
A scientific calculator that shows its working, fractions, ratios, factors and primes.
Scientific calculator
Trig, powers, roots and logs, with the order of working shown.
Fraction calculator
Add, subtract, multiply, divide and simplify fractions.
Ratio calculator
Simplify ratios, solve A:B = C:D and share an amount.
Factor calculator
All factors, factor pairs and prime factorization.
Prime number checker
Is a number prime? See the factor that proves it.
GCF calculator
Greatest common factor (HCF) of two or more numbers.
LCM calculator
Least common multiple of two or more numbers.
Quadratic formula calculator
Solve ax² + bx + c = 0 with exact roots and steps.
Graphs, shapes and density
Plot a graph, find a slope, solve a right triangle or a circle, and work out density.
Graphing calculator
Plot y = f(x), with crossing points and a table of values.
Slope calculator
Slope, line equation and angle from two points.
Pythagorean theorem calculator
Missing side of a right triangle with a² + b² = c².
Circle calculator
Circumference, area, radius and diameter from any one.
Density calculator
Density, mass or volume with ρ = m/V, any units.
Averages and statistics
Mean, median, mode, range and standard deviation, with every step shown.
Random numbers and words
Fair random numbers, list picks and words from your browser's secure random source.