Calculators
Open Calculators on Happytails.ai. This view has the same page content and links, with explicit tool capabilities. Read the processing notes before using a tool.
Page guide
Find the right tool and get straight to your task.
No account needed.Coin flip
Flip a virtual coin and get Heads or Tails.
Random number
Generate random whole numbers within an inclusive range.
Concrete calculator
Estimate concrete volume, waste allowance and the number of bags for a slab or cylinder.
Percentage
Find a percentage of a number.
Scientific calculator
A proper calculator for powers, roots and trigonometry.
Dice roller
Roll virtual dice and see each roll and the total.
Graphing calculator
Plot functions, explore intersections and download a graph or table of values.
Tip
Calculate a tip, the total bill, and each person’s share.
Fractions
Add, subtract, multiply, or divide two fractions.
Percentage difference calculator
Compare two values without picking a starting point.
Square footage
Calculate rectangular floor area in square feet and square meters.
Margin
Calculate profit and profit margin from cost and selling price.
Percentage change
Calculate the percentage increase or decrease between two values.
Ratio
Simplify a ratio of two whole numbers.
Slope calculator
Find the slope, rise and run between two points.
Volume calculator
Calculate the volume of a box, cylinder, or sphere.
GCF calculator
Find the greatest common factor of a list of integers.
Lcm
Find the least common multiple of whole numbers.
Prime number checker
Check whether a whole number is prime.
Average
Find the mean, median, sum, minimum, and maximum of a list of numbers.
Pace calculator
Find your pace, finish time or distance, with kilometre and mile splits.
Standard deviation
Calculate the mean and standard deviation of a set of numbers.
Pythagorean theorem calculator
Find a missing side of a right triangle.
Quadratic formula calculator
Solve a quadratic, including complex and repeated roots.
All tools (208)
About calculators
These free online calculators cover math, money, home projects and hobbies in one place. Everyday picks include the Percentage, Tip, Discount and Fractions calculators, along with a Scientific calculator and a Graphing calculator for schoolwork. Home and garden projects are covered by the Concrete calculator, Square footage, Paint and Flooring calculators, and statistics users get tools such as Standard deviation, Z-score and Sample size. Coin flip, Dice roller and Random number handle quick decisions.
Search for the exact task rather than a general calculator. A dedicated tool such as the Concrete calculator asks for the right inputs and handles unit conversions for you. Check that your inputs use the units the calculator expects, and round only the final answer.
Popular calculators
Common questions
How accurate are the results?
The calculators apply standard formulas to the values you enter and show the result with sensible rounding. Accuracy depends on your inputs, so double check units and measurements. For building materials, add a waste allowance before ordering.
Is the random number generator truly random?
Random number, Coin flip and Dice roller use the random number source built into your browser. That is fair for games, draws and classroom use. For passwords or security keys, use a dedicated generator such as the Password generator instead.
Do I need to install anything?
No. Every calculator opens in your browser on a phone, tablet or computer. The popular calculators, including Percentage, Tip, Scientific calculator and Graphing calculator, run in your browser, so your numbers are not sent to our server.