The everyday calculator collection

Accurate online calculators.
Clear methods, dependable answers.

Choose from 31 free calculators for time, grades, finance, math and home projects. Each tool includes a formula, worked example and practical limits—no sign-up required.

Explore the collection31 calculators

Education

2 calculators

Final Grade Calculator

Find the score needed on a final exam or remaining assignment to reach a target course grade.

Cumulative & Weighted GPA Calculator

Calculate term or cumulative GPA with credits, letter grades, prior GPA, and optional course boosts.

Time & Pay

4 calculators

Hours Calculator

Calculate hours and minutes between two clock times, including shifts that cross midnight.

Time Calculator

Add or subtract durations in days, hours, minutes, and seconds.

Time Duration Calculator

Find the exact elapsed days, hours, minutes, and seconds between two date-times.

Overtime & Time Card Calculator

Total weekly shifts, deduct breaks, split regular and overtime hours, and estimate gross pay.

Finance

7 calculators

Bond & Savings Value Calculator

Price a fixed-rate coupon bond, solve yield to maturity, or project known-rate savings growth.

CD Interest Calculator

Calculate maturity balance and interest from APY or nominal APR with optional tax illustration.

Salary Increase Calculator

Calculate a salary raise from a percentage or compare old and new annual pay.

CPM Calculator

Calculate advertising CPM, campaign cost, or impressions from the other two campaign metrics.

Dividend Calculator

Estimate dividend yield, annual income, total dividends, and a transparent reinvestment projection.

Credit Card Payoff Calculator

Estimate payoff time, total interest, fees, and final payment for a fixed-rate credit card balance.

Markup Calculator

Calculate selling price, gross profit, markup on cost, and the corresponding gross margin percentage.

Construction

7 calculators

Gravel Calculator

Estimate gravel volume, bulk weight, order allowance, and material cost.

Mulch Calculator

Estimate cubic yards, cubic feet, full bag count, and bag cost for a garden bed.

Voltage Drop Calculator

Estimate resistive voltage drop using conductor size, material, distance, load, phase, and temperature.

Stair Calculator

Calculate riser count, actual rise, tread count, total run, angle, and stringer length.

Roof Pitch & Area Calculator

Convert rise and run into angle, slope, area multiplier, roof area, and roofing squares.

Square Footage Calculator

Calculate square footage for rectangles, circles, triangles, or a known area and convert it to other area units.

Asphalt Calculator

Estimate asphalt surface area, compacted volume, order weight, and material cost from project dimensions.

Math

6 calculators

Scientific Calculator

Evaluate scientific expressions with safe parsing, standard precedence, functions, and angle modes.

Scientific Notation Calculator

Convert and calculate scientific notation with exact decimal integers and controlled division precision.

Mixed Fraction Calculator

Add, subtract, multiply, or divide mixed numbers with exact integer fraction arithmetic.

Average Calculator

Calculate an arithmetic mean or weighted average, together with count, sum, median, and range.

Median Calculator

Find the median of a number list and review its sorted count, mean, minimum, maximum, and sum.

Volume Calculator

Calculate volume for cylinders, spheres, cones, cubes, prisms, frustums, and ellipsoids with unit conversion.

Health & Fitness