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Free online calculators for confident decisions.
Use free online calculators with checked formulas, clear assumptions and step-by-step results—not just a final number.
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01 · Category
Free online calculators for construction & engineering
These free online calculators estimate dimensions, materials and engineering values from measured inputs.
Explore the free online calculators in this category.
| Calculator | Best used for |
|---|---|
| Asphalt Calculator | Estimate asphalt volume, weight, tons, and material allowance from project dimensions. |
| Concrete Calculator | Estimate concrete volume and whole purchase units for several common project shapes. |
| Concrete Slab Calculator | Estimate area, volume, whole bags, or ready-mix units for one or more rectangular slabs. |
| Cubic Feet Calculator | Calculate rectangular volume in cubic feet, cubic yards, and cubic meters from length, width, and height. |
| Cubic Yard Calculator | Convert rectangular project dimensions into cubic yards, cubic feet, and cubic meters. |
| Fill Dirt Calculator | Convert target compacted fill volume into loose purchase volume with an explicit factor and waste. |
| Framing Calculator | Estimate studs, plate length, gross wall area, and standard sheathing panels for a simple straight wood-framed wall. |
| Gravel Calculator | Estimate gravel volume and weight for a rectangular landscaping or construction area. |
| HVAC Duct Calculator | Estimate geometric round and square duct dimensions from airflow in CFM and a chosen target velocity in FPM. |
| Mulch Calculator | Convert rectangular landscape coverage and mulch depth into bags or bulk volume. |
| Roof Pitch Calculator | Convert roof rise and run into pitch, slope percentage, angle, and rafter length for planning. |
| Sand Calculator | Estimate sand volume and purchase weight from dimensions, editable bulk density and waste. |
| Square Foot Calculator | Calculate rectangular area in square feet, square meters, and square yards from dimensions. |
| Stone Calculator | Estimate landscaping stone volume, weight, tons, and waste from project dimensions and material density. |
| Tank Volume Calculator | Calculate full geometric volume for rectangular, vertical cylindrical, or horizontal cylindrical tanks and convert it to liters and US gallons. |
| Topsoil Calculator | Estimate topsoil coverage volume, bags, bulk units, optional weight and cost. |
| Voltage Drop Calculator | Estimate electrical voltage drop from circuit length, current, AWG conductor size, material, phase, and supply voltage. |
| Wallpaper Calculator | Estimate whole wallpaper rolls from wall size, roll size, vertical pattern repeat, and a chosen waste allowance. |
02 · Category
Free online calculators for math
These free online calculators solve statistics, algebra, fractions, geometry and number-format problems.
Explore the free online calculators in this category.
| Calculator | Problem type |
|---|---|
| Binomial Distribution Calculator | Calculate exact, at-most, or at-least binomial probabilities from trials, successes, and a fixed success probability. |
| Fraction Simplifier Calculator | Reduce an integer fraction to lowest terms and show its greatest common divisor, decimal value, and mixed number. |
| Mixed Fraction Calculator | Add, subtract, multiply, or divide mixed numbers and convert between mixed and improper fractions. |
| Percent Difference Calculator | Calculate the percent difference between two values using their average as the reference. |
| Pythagorean Theorem Calculator | Find a missing side of a right triangle using the Pythagorean theorem. |
| Quadratic Formula Calculator | Solve a quadratic equation from coefficients a, b, and c and identify real or complex roots. |
| Scientific Notation Calculator | Convert decimal numbers to scientific notation and expand scientific notation into standard decimal form. |
| Standard Deviation Calculator | Calculate population or sample standard deviation, mean, variance, and spread for a data set. |
03 · Category
Free online calculators for business & finance
These free online calculators help you work out prices, advertising metrics, interest and commercial margins.
Explore the free online calculators in this category.
| Calculator | Decision supported |
|---|---|
| CD Interest Calculator | Estimate certificate of deposit interest, maturity value, and annual percentage yield from deposit terms. |
| CPM Calculator | Calculate advertising cost per thousand impressions, campaign cost, or impressions from two known values. |
| Discount Calculator | Calculate sale price and savings from an original price and percentage discount. |
| Markup Calculator | Calculate selling price, markup amount, markup percentage, or gross margin from product cost. |
| Reverse Sales Tax Calculator | Remove a known sales-tax percentage from a tax-inclusive total to estimate the pre-tax subtotal and the tax amount included. |
| Time to Decimal Calculator | Convert clock time in hours and minutes to decimal hours, or convert decimal hours back to normalized hours and minutes. |
04 · Category
Free online calculators for other
These free online calculators support education, science, brewing and everyday planning.
Explore the free online calculators in this category.
| Calculator | Task |
|---|---|
| ABV Calculator | Estimate alcohol by volume from original and final gravity readings for fermented beverages. |
| Chronological Age Calculator | Calculate chronological age in years, months, and days from a birth date and reference date. |
| College GPA Calculator | Calculate a term college grade point average from course credits and grade points. |
| Cousin Relationship Calculator | Name a cousin degree and removal from each person's generation distance to their closest shared ancestor. |
| Cumulative GPA Calculator | Calculate an updated cumulative GPA from prior credits, prior GPA, and current term credits and GPA. |
| Dilution Calculator | Determine the volume of stock solution and diluent needed to prepare a target concentration. |
| Pizza Calculator | Compare pizza sizes by circular area and price per square inch to choose the better value. |
| Weighted Grade Calculator | Calculate a course grade from assignment scores and category weights. |
How to use free online calculators
Use these free online calculators in three simple steps.
Find the calculator
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Enter your numbers
Fill in the boxes in free online calculators and choose the units you measured in.
Check the result
Check the numbers and units in free online calculators before using the answer. If money, health or safety is involved, ask a professional.
These free online calculators are reviewed by the Calculator Center Editorial Team. Last reviewed: . Unit conversions follow NIST guidance.
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