Free Online Calculators
& Everyday Tools
Calculate, convert and solve everyday problems in seconds.
Fast • Accurate • Always Free
🔥 Most Popular
cm to Inches Converter
Convert centimeters to inches — most searched length converter
🔥 Popular❄️Debt Snowball Calculator
Pay off debt faster — see payoff order, interest saved, debt-free date
🔥 Popular⚖️kg to lbs Converter
Convert kilograms to pounds instantly — 1 kg = 2.205 lbs
🔥 Popular🏦CD Calculator
Calculate Certificate of Deposit earnings with compound interest
🔥 Popular🏷️Percent Off Calculator
Find sale price instantly — great for shopping and discount deals
🔥 Popular📅Days From Today Calculator
Find exact date 30, 60, 90 days from today — deadlines made easy
🔥 Popular💰 Finance Calculators
Mortgage Calculator
Monthly payment, total interest, PMI estimate & full amortization schedule
New❄️Debt Snowball Calculator
Pay off debt faster — payoff order, interest saved, debt-free date
⭐ Most engaged tool🏦CD Calculator
Calculate Certificate of Deposit earnings with compound interest
🏠Mortgage Payoff Calculator
See how extra payments reduce your mortgage term and total interest
📆Biweekly Mortgage Calculator
Save years off your mortgage by switching to biweekly payments
🧾Reverse Sales Tax Calculator
Find original price before tax from the total amount paid
🏙️Cost of Living Calculator
Compare salaries between cities — see what you need in a new city
New📊APR Calculator
Calculate true Annual Percentage Rate including fees for any loan
New🏦Roth IRA Calculator
See how your Roth IRA grows tax-free — balance at retirement
New💼401k Calculator
Calculate 401k retirement balance including free employer match
New📋Amortization Calculator
Full loan payment schedule — principal, interest & balance every month
New📈Compound Interest Calculator
See how your money grows with compounding — includes monthly contributions & year-by-year table
New💰Savings Calculator
Calculate balance, time to reach a goal, or monthly savings needed — 3 modes in one tool
New🏦Personal Loan Calculator
Find your monthly payment, total interest, and full year-by-year amortization schedule
New🚗Car Payoff Calculator
Calculate car loan payment with down payment, trade-in, tax, and extra payment savings
New📅 Date & Time Tools
30 Days From Today
What date is exactly 30 days from today? Net 30 payment deadline
🗓️60 Days From Today
Find the exact date 60 days (2 months) from today's date
📆90 Days From Today
Find the date 90 days (one quarter / 3 months) from today
📆Weeks in a Year
52 weeks + 1 day — work weeks, school weeks & pay periods
New🕐Hours in a Year
8,760 hours per year — work hours & salary to hourly conversion
New⏱️Minutes in a Day
1,440 minutes in a day — complete time unit reference
New⏰Seconds in a Year
31,536,000 seconds per year — exact with π × 10⁷ trick
New🗓️Hours in a Week
168 hours in a week — work week hours, free time breakdown
New🕐Hours in a Month
730 avg hours per month — exact hours for any month
🎖️Military Time Converter
Convert military time to standard time — 1300 = 1:00 PM, 0800 = 8:00 AM
New⏱️Time to Decimal Calculator
Convert hours & minutes to decimal for timesheets and payroll
🏷️ Discount Calculator
View All 308 →⚖️ Unit Converters
kg to lbs Converter
Convert kilograms to pounds — 1 kg = 2.205 lbs
56 pre-calculated pages →📐cm to Inches
Convert centimeters to inches instantly
📏Meters to Feet
Convert meters to feet and inches — height conversion table included
37 height pages →📐Yards to Meters
Convert yards to meters — football fields, fabric, golf distances
109 pre-calculated pages →💾MB to GB Converter
Convert megabytes to gigabytes — binary and decimal results
53 pre-calculated pages →🛣️km to Miles
Convert kilometers to miles — includes race distance chart
🌡️Celsius to Fahrenheit
Temperature converter — °C to °F applied instantly
🌡️Fahrenheit to Celsius
Convert °F to °C — body temp, freezing, boiling and more
🪣Liters to Gallons
Convert liters to US or Imperial gallons — 1 gal = 3.785 L
🧃Oz to Quarts
Convert fluid ounces to quarts — 1 quart = 32 fl oz
🥄Cups to Tablespoons
How many tablespoons in a cup? 1 cup = 16 tbsp — all fractions
🥛Cups to Gallons
Convert cups to gallons for large cooking quantities
⚖️Ounces in a Pound
How many ounces in a pound? 1 lb = 16 oz converter
🚤Knots to MPH
Convert nautical speed — knots to miles per hour
🍺Oz to Pint Converter
Convert fluid ounces to pints — 1 pint = 16 fl oz
New🪣Quart to Gallon
Convert quarts to gallons — 1 gallon = 4 quarts
New💧Gallons to Liters
Convert US gallons to liters — 1 gal = 3.785 L
New🔩Bar to PSI
Convert bar to PSI — tire pressure and industrial pressure
New✈️mph to Knots
Convert miles per hour to knots — aviation and maritime speed
New🌡️atm to Bar
Convert atmospheres to bar — 1 atm = 1.01325 bar
New⚗️Grain to mg Converter
Convert grains to milligrams — 1 grain = 64.799 mg (aspirin, bullets)
New💍Pennyweight to Grams
Convert dwt to grams — 1 dwt = 1.555 g (jewelry & precious metals)
New🥇Troy Ounces to Pounds
Convert troy oz to lbs — 1 troy oz = 0.06857 lbs (gold & silver)
New📊 Percentage Calculators
Percentage Calculator
What is X% of Y? Three percentage calculators in one
New📈Percentage Increase Calculator
Find % increase between two values — or new value after increase
New📉Percentage Decrease Calculator
Find % decrease between two values — or new value after decrease
New🏷️Markup Calculator
Find selling price from cost + markup %, or calculate markup %
New💹Margin Calculator
Calculate gross profit margin % from revenue and cost
New🧮 Math Calculators
Binary to Text Translator
Convert binary code to text or text to binary — 01001000 01101001 = Hi
New🔢Decimal to Fraction Calculator
Convert 0.5 → 1/2, 0.625 → 5/8 — shows steps and mixed number
New➗Fraction Calculator
Add, subtract, multiply, or divide fractions — simplified with steps
New📏Square Footage Calculator
Calculate area in sq ft — rectangle, triangle, circle, L-shape
📐Pythagorean Theorem Calculator
Find any side of a right triangle using a² + b² = c²
🏗️Concrete Calculator
Cubic yards, bags needed for slabs, footings & columns
New🚗Tire Size Calculator
Decode any tire size — diameter, sidewall, circumference, speedometer error
🎓GPA Calculator
Calculate semester or cumulative GPA from letter grades or percentages
New🏥 Health Calculators
BAC Calculator
Estimate Blood Alcohol Content by drinks, weight & time
💪Body Fat Calculator
Body fat % using U.S. Navy Method or BMI Method — category, lean mass, fat mass
⚖️BMI Calculator
Body Mass Index — healthy weight range, WHO category, weight to lose or gain
NewWhy ComputeZap?
Finance Calculators — Make Smarter Money Decisions
Our finance calculators handle the math so you can focus on the decision. The CD calculator computes exact interest earnings using the compound interest formula. The mortgage payoff calculator shows how much interest you save by making extra payments. The debt snowball calculator shows your debt-free date and total interest saved — all instantly in your browser.
Unit Converters — Accurate to 6 Decimal Places
Every converter on ComputeZap uses the official conversion factors — no rounding shortcuts. The cm to inches converter uses exactly 0.393701 inches per centimeter. Liters to gallons supports both US (÷3.78541) and Imperial (÷4.54609) gallons. Whether you are cooking, traveling, or working with international specs, the answer is always precise.
308 Specific Discount Pages — Instant Answers
Need to know what 30% off $50 is? We have a dedicated page for every common discount combination — from 5% off $5 to 75% off $1,000. Each page shows the sale price, savings amount, and related calculations. No need to do the math — just bookmark the page you use most.