Find your tool. Formula, example and result on the same page.
Calculate average density from mass divided by occupied volume. Use kilograms and cubic metres for an SI result.
Calculate uniform pressure from the force normal to a surface. The area must be expressed in square metres.
Estimate the pressure increase below a fluid surface. Atmospheric or other surface pressure must be added separately for absolute pressure.
Calculate the buoyant force from displaced fluid volume. This is the upward force, not the net force on the object.
Calculate torque magnitude using the angle between position vector and force. At 90 degrees the lever arm is fully effective.
Find the inward net force required for circular motion at the entered speed and radius.
Apply Hooke’s law within a spring’s elastic range. The restoring force opposes displacement and stored energy is nonnegative.
Estimate the period of a simple pendulum for small angular oscillations, negligible friction and a point-like mass.
Find wavelength from wave speed and frequency in the same medium. Wave speed is an input rather than a universal constant.
Convert cyclic frequency to period and angular frequency. Hertz means cycles per second, not radians per second.
Calculate current and dissipated power for an ideal ohmic resistor with positive resistance. This is a component model, not a wiring design.
Calculate DC electrical power. AC systems may require RMS values, phase information and power factor not represented here.
Add nonnegative ideal resistor values connected in series. Values must all use ohms.
Find equivalent resistance for positive ideal resistors in parallel. Zero resistance is excluded to avoid division by zero.
Calculate energy stored in an ideal capacitor. Capacitance is entered in microfarads and voltage in volts.
Estimate sensible heat with constant specific heat capacity and no phase change. A temperature difference in kelvin equals one in Celsius.
Estimate paint volume after deducting doors and windows from your area. Coverage depends on the product and surface condition.
Estimate whole packs of flooring including a waste allowance. Irregular cuts and installation pattern can change material needs.
Estimate whole tiles using nominal face dimensions. Grout spacing and cuts are not modelled individually.
Estimate concrete volume for a rectangular slab. This calculates material volume only and does not specify structural reinforcement.
Estimate loose gravel volume and mass using a supplier-provided bulk density. Compaction and moisture may change the actual quantity.
Estimate soil volume for a uniform layer. Settlement and compaction are excluded from the geometric volume.
Estimate whole bags for a uniform mulch layer. Bag volume and depth are converted to the same volume unit.
Estimate rolls from full-height strips. Include trimming in height; pattern repeats and openings require your own allowance.
Count posts for one open straight run with a post at each end. Gates, corners and closed loops need separate treatment.
Calculate slope percentage and angle from rise and horizontal run in the same unit. Material rules and local codes are not evaluated.
Divide a total rise into equal risers no higher than your target. Tread depth, landings and building-code compliance are not determined.
Estimate water volume in a rectangular pool using average water depth. Steps, curves and displaced volume are excluded.
Estimate filling time at a constant flow rate with no leaks or outflow. Supply pressure changes can alter actual time.
Estimate energy and variable usage cost from appliance power and time. Fixed fees, tax rules and changing tariffs are excluded.
Estimate consumption cost using one flat rate. Tiered tariffs, sewage charges and fixed fees are excluded.
Estimate fuel and cost at constant consumption. Include the full round-trip distance if you want a return journey estimate.
Calculate fuel economy from a measured distance and fuel quantity. Both outputs describe the same trip with inverse conventions.
Estimate charge time with a constant average power and efficiency. Real charging can taper; use average power rather than peak rating.
Estimate runtime from nominal energy and a usable-capacity allowance. Battery chemistry, temperature and current-dependent losses are not modelled.
Scale one ingredient in direct proportion to servings. Cooking time and temperature do not generally scale by the same factor.
Resize an image to a new width while preserving its aspect ratio. Rounded pixel height may cause a tiny ratio difference.
Estimate screen pixel density assuming square pixels and the stated active-display diagonal in inches.
Add or subtract calendar days, counting weekends and holidays. UTC date arithmetic prevents daylight-saving shifts.
Find the ISO weekday number for a Gregorian calendar date. Monday is 1 and Sunday is 7, independent of local timezone.
Find the ordinal day from 1 to 365 or 366. Leap days are included automatically.
Find the ISO week and week-year. Dates near New Year can belong to the preceding or following ISO year.
Return the number of days in a Gregorian year. Years divisible by 100 are common years unless also divisible by 400.
Find the length of a Gregorian calendar month, including February in leap years. Month numbers run from January 1 to December 12.
Count weekdays excluding the starting date and including the ending date. National and local public holidays are not removed.
Add Monday-to-Friday days after a starting date. Holidays are not excluded, so this is not a jurisdiction-specific deadline calculator.
Convert an hours-and-minutes duration into decimal hours. Thirty minutes is 0.5 hour, not 0.30 hour.
Subtract an unpaid break from each identical shift. This totals hours only and does not apply local overtime rules.
No matching calculators.
Choose the right calculation
Housing & loans
Compare loan payments and broader housing costs using separate amounts. Keep the financed principal and rate constant when testing another term.
Everyday money
Separate price, tax, fees and repayments with the calculator that matches your transaction. Compare scenarios using the same currency and cost basis.
Pay & work
Choose gross pay conversion or the country-specific payroll calculation that matches your question. Read the pay period and deductions included in the result.
Investing
Choose a one-time investment, regular contributions or deposit model that matches your cash flows. Compare total contributions alongside projected value.
Maths
Choose the operation that matches your percentage, ratio or equation problem. Match each symbol in the formula to the example input.
Dates & age
Choose elapsed days, calendar position or completed age according to your question. Date conventions matter at month ends and around leap days.
Unit converters
Select the quantity, then choose its source and destination units. Read variant names before converting units with similar labels.
Geometry
Choose a shape and enter the dimensions its formula requires. Check whether each label asks for a radius, diameter, perpendicular height or semiaxis.
Statistics
Choose the measure that matches your question about centre, spread or probability. Sample estimates, population measures and probability models use different assumptions.
Physics
Choose the physical quantity you want to find and supply the units required by its equation. Read the model assumptions before applying the result to a real system.
Home & construction
Estimate material quantities or project costs from measured dimensions. Choose the tool matching the material and measurement before comparing prices.