Online Calculators
Free online calculators and tools for the numbers in your day — instant, accurate, no signup.
ziffaro brings fast, no-nonsense calculators together in one place. Every tool runs right in your browser, shows the result instantly, and is completely free — no account needed. From health and math to everyday conversions, get your numbers figured in seconds.
A1C Calculator
A1C ↔ average glucose
BMI Calculator
Body Mass Index + category
BMR Calculator
Basal metabolic rate
TDEE Calculator
Maintenance calories
Calorie Calculator
Daily calories for your goal
Body Fat Calculator
U.S. Navy method
Ideal Weight Calculator
Devine, Hamwi & BMI range
Average Calculator
Mean, median, weighted, %
Cubic Feet Calculator
Volume in cubic feet
Surface Area Calculator
Cube, sphere, cylinder…
Overtime Calculator
Overtime & total pay
Average Time Calculator
Mean of multiple times
Average Rate of Change Calculator
Slope between two points
Dice Average Calculator
Average dice roll (NdX)
Average Atomic Mass Calculator
From isotope abundances
Average Acceleration Calculator
Δv ÷ Δt
Dividend Calculator
Income, yield & reinvestment
Average Velocity Calculator
Displacement ÷ time
Average Daily Balance Calculator
Credit-card interest
Average Value of a Function Calculator
Mean value over [a, b]
Weighted Grade Calculator
Grades by weight
Semester Grade Calculator
Combine term grades
Length Converter
mm, cm, m, in, ft, mi…
Weight Converter
g, kg, oz, lb, st…
Temperature Converter
Celsius, Fahrenheit, Kelvin
Percentage Calculator
% of, is what %, % change
Paycheck Calculator
Take-home pay after tax
Income Tax Calculator
Federal + state income tax
Mortgage Calculator
Monthly payment & interest
Mortgage Recast Calculator
New payment after a lump sum
Pay Off Mortgage Early Calculator
Extra payments, interest saved
Capital Gains Tax Calculator
Federal + state on your gain
1099 Tax Calculator
Self-employment + income tax
Salary Increase Calculator
Raise %, dollar difference
Auto Loan Calculator
Car loan payment & interest
Car Payment Calculator
Monthly car payment
Tip Calculator
Tip, total & split
ROI Calculator
Return on investment %
Sales Tax Calculator
Add or reverse sales tax
Compound Interest Calculator
Growth with contributions
401(k) Calculator
Retirement balance projection
Markup Calculator
Price, profit & margin
Break-Even Calculator
Units to cover costs
Net Worth Calculator
Assets minus liabilities
Debt Snowball Calculator
Smallest balance first
Debt Avalanche Calculator
Highest APR first
FERS Retirement Calculator
Federal pension estimate