All Tools

// 69 calculators · click any to jump

Unit Converters10

Angle ConverterArea ConverterEnergy ConverterLength ConverterMass / Weight ConverterPressure ConverterSpeed ConverterTemperature ConverterTime ConverterVolume Converter

Computing3

Color ConverterDigital Data ConverterNumber System Converter

Accounting9

Compound Interest CalculatorLoan & Mortgage Payment CalculatorMarkup & Margin CalculatorPercent Change CalculatorROI CalculatorSales Tax CalculatorSimple Interest CalculatorStraight-Line Depreciation CalculatorTip Calculator

Real Estate6

Cap Rate CalculatorCash-on-Cash Return CalculatorGross Rent Multiplier CalculatorMortgage Affordability CalculatorProperty Tax CalculatorRefinance Break-Even Calculator

Date & Time6

Add or Subtract DaysAge CalculatorBusiness Days CalculatorCountdown / Days UntilDate Difference CalculatorWeekday Lookup

Nutrition11

BMI CalculatorBMR & TDEE CalculatorBody Fat CalculatorCalories from Macros CalculatorGlycemic Load CalculatorIdeal Body Weight CalculatorLean Body Mass CalculatorMacros from Calories CalculatorProtein Needs CalculatorWaist-to-Hip & Waist-to-Height Ratio CalculatorWater Intake Calculator

Health & Fitness6

Calories Burned by ActivityHeart Rate Zones CalculatorPregnancy Due Date CalculatorRunning Pace CalculatorStep Calorie BurnVO₂ max Calculator

Construction & DIY6

Concrete Volume CalculatorLumber Board-Feet CalculatorPaint Coverage CalculatorRoof Pitch CalculatorStair CalculatorTile Calculator

Science7

Density CalculatorGravitational Potential Energy CalculatorIdeal Gas Law CalculatorKinetic Energy CalculatorMolarity CalculatorpH CalculatorWavelength ↔ Frequency Calculator

Engineering5

Electric Power CalculatorFuel Economy CalculatorOhm's Law CalculatorParallel Resistors CalculatorVoltage Divider Calculator

Unit Converters

// metric · imperial · scientific

Angle

Convert between units

Input value

Degree (°)Radian (rad)Degree (°)Gradian (gon)Turn (rev)Arcminute (′)Arcsecond (″)

Convert to

Radian (rad)Radian (rad)Degree (°)Gradian (gon)Turn (rev)Arcminute (′)Arcsecond (″)

Result0.017453293 rad

Equation1 deg → 0.017453293 rad

Open

Area

Convert between units

Input value

Square meter (m²)Square millimeter (mm²)Square centimeter (cm²)Square meter (m²)Hectare (ha)Square kilometer (km²)Square inch (in²)Square foot (ft²)Square yard (yd²)AcreSquare mile (mi²)

Convert to

Square foot (ft²)Square millimeter (mm²)Square centimeter (cm²)Square meter (m²)Hectare (ha)Square kilometer (km²)Square inch (in²)Square foot (ft²)Square yard (yd²)AcreSquare mile (mi²)

Result10.76391 ft2

Equation1 m2 → 10.76391 ft2

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Energy

Convert between units

Input value

Joule (J)Joule (J)Kilojoule (kJ)Calorie (cal)Kilocalorie / food calorie (kcal)Watt-hour (Wh)Kilowatt-hour (kWh)British thermal unit (BTU)Foot-pound (ft·lb)Electronvolt (eV)

Convert to

Calorie (cal)Joule (J)Kilojoule (kJ)Calorie (cal)Kilocalorie / food calorie (kcal)Watt-hour (Wh)Kilowatt-hour (kWh)British thermal unit (BTU)Foot-pound (ft·lb)Electronvolt (eV)

Result0.23900574 cal

Equation1 J → 0.23900574 cal

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Length

Convert between units

Input value

Meter (m)Millimeter (mm)Centimeter (cm)Meter (m)Kilometer (km)Inch (in)Foot (ft)Yard (yd)Mile (mi)Nautical Mile (nmi)

Convert to

Foot (ft)Millimeter (mm)Centimeter (cm)Meter (m)Kilometer (km)Inch (in)Foot (ft)Yard (yd)Mile (mi)Nautical Mile (nmi)

Result3.2808399 ft

Equation1 m → 3.2808399 ft

Open

Mass

Convert between units

Input value

Kilogram (kg)Milligram (mg)Gram (g)Kilogram (kg)Metric Ton (t)Ounce (oz)Pound (lb)Stone (st)US Ton (short)UK Ton (long)

Convert to

Pound (lb)Milligram (mg)Gram (g)Kilogram (kg)Metric Ton (t)Ounce (oz)Pound (lb)Stone (st)US Ton (short)UK Ton (long)

Result2.2046226 lb

Equation1 kg → 2.2046226 lb

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Pressure

Convert between units

Input value

Atmosphere (atm)Pascal (Pa)Kilopascal (kPa)Megapascal (MPa)BarAtmosphere (atm)Millimeter of mercury (mmHg)Inch of mercury (inHg)Pound / square inch (psi)Torr

Convert to

Pound / square inch (psi)Pascal (Pa)Kilopascal (kPa)Megapascal (MPa)BarAtmosphere (atm)Millimeter of mercury (mmHg)Inch of mercury (inHg)Pound / square inch (psi)Torr

Result14.695949 psi

Equation1 atm → 14.695949 psi

Open

Speed

Convert between units

Input value

Kilometer / hour (km/h)Meter / second (m/s)Kilometer / hour (km/h)Mile / hour (mph)Foot / second (ft/s)Knot (nmi/h)

Convert to

Mile / hour (mph)Meter / second (m/s)Kilometer / hour (km/h)Mile / hour (mph)Foot / second (ft/s)Knot (nmi/h)

Result0.62137119 mph

Equation1 kmh → 0.62137119 mph

Open

Temperature

Celsius · Fahrenheit · Kelvin · Rankine

Input value

Celsius (°C)Celsius (°C)Fahrenheit (°F)Kelvin (K)Rankine (°R)

Convert to

Fahrenheit (°F)Celsius (°C)Fahrenheit (°F)Kelvin (K)Rankine (°R)

Result68 °F

Open

Time

Convert between units

Input value

Hour (h)Millisecond (ms)Second (s)Minute (min)Hour (h)Day (d)Week (wk)Month (avg, 30.4375 d)Year (Julian, 365.25 d)

Convert to

Minute (min)Millisecond (ms)Second (s)Minute (min)Hour (h)Day (d)Week (wk)Month (avg, 30.4375 d)Year (Julian, 365.25 d)

Result60 min

Equation1 h → 60 min

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Volume

Convert between units

Input value

Liter (L)Milliliter (mL)Centiliter (cL)Liter (L)Cubic meter (m³)Teaspoon (US tsp)Tablespoon (US tbsp)Fluid ounce (US fl oz)Cup (US)Pint (US)Quart (US)Gallon (US)Gallon (UK)

Convert to

Gallon (US)Milliliter (mL)Centiliter (cL)Liter (L)Cubic meter (m³)Teaspoon (US tsp)Tablespoon (US tbsp)Fluid ounce (US fl oz)Cup (US)Pint (US)Quart (US)Gallon (US)Gallon (UK)

Result0.26417205 gal_us

Equation1 L → 0.26417205 gal_us

Open

Computing

// number systems · colors · data

Colors

HEX · RGB · HSL · HSV · CMYK

Input formatHEXRGBHSLHSVCMYK

HEX

Equivalents

HEX#1F7BFF

RGBrgb(31, 123, 255)

HSLhsl(215, 100%, 56%)

HSVhsv(215, 88%, 100%)

CMYKcmyk(88%, 52%, 0%, 0%)

Open

Digital data

Convert between units

Input value

Megabyte (MB)Bit (b)Byte (B)Kilobyte (kB, 1000 B)Megabyte (MB)Gigabyte (GB)Terabyte (TB)Kibibyte (KiB, 1024 B)Mebibyte (MiB)Gibibyte (GiB)Tebibyte (TiB)

Convert to

Mebibyte (MiB)Bit (b)Byte (B)Kilobyte (kB, 1000 B)Megabyte (MB)Gigabyte (GB)Terabyte (TB)Kibibyte (KiB, 1024 B)Mebibyte (MiB)Gibibyte (GiB)Tebibyte (TiB)

Result0.95367432 MiB

Equation1 MB → 0.95367432 MiB

Open

Number Systems

Binary · Octal · Decimal · Hex

Value

Decimal (base 10)Binary (base 2)Octal (base 8)Decimal (base 10)Hexadecimal (base 16)

Equivalents

Binary11111111

Octal377

Decimal255

HexadecimalFF

Open

Accounting

// finance · pricing · everyday math

Compound Interest

A = P (1 + r/n)^(nt)

Principal (P)

Annual Rate %

Years (t)

Compounds / year (n)

Final Amount$1,647.01

Interest earned$647.01

Total contributions$1,000.00

Open

Loan / Mortgage Payment

Fixed-rate amortizing loan

Loan amount

Annual Rate %

Term (years)

Monthly Payment$1,580.17

Total paid$568,861.22

Total interest$318,861.22

Open

Markup & Margin

Pricing analysis

Cost

Selling price

Profit$20.00

Markup50 %

Margin33.333333 %

Open

Percent Change

Increase / decrease between two values

Original

New

Change30 %

Open

ROI

Return on investment & annualized return

Initial value

Final value

Holding period (years)

ROI45 %

Net gain$4,500.00

Annualized return13.18512 %

Open

Sales Tax

Compute tax and grand total

Pre-tax price

Tax rate %

Total$108.24

Tax$8.25

Open

Simple Interest

I = P · r · t

Principal

Annual Rate %

Years

Interest$150.00

Total amount$1,150.00

Open

Depreciation

Straight-line method

Asset cost

Salvage value

Useful life (years)

Annual depreciation$4,400.00

Total depreciable$22,000.00

Open

Tip

Restaurant tip splitter

Bill

Tip %

People

Per person$38.06

Tip total$11.61

Bill total$76.11

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Real Estate

// mortgages · rentals · ROI

Cap Rate

Capitalization rate = NOI / property value

Annual NOI

Property value

Cap rate6 %

Open

Cash-on-Cash Return

Annual cash flow / cash invested

Annual cash flow (post-debt)

Total cash invested

Cash-on-cash return7.5 %

Open

Gross Rent Multiplier

GRM = price / annual gross rent

Property price

Annual gross rent

GRM11.111111

Open

Mortgage Affordability

28/36 rule — how much house can you afford

Gross monthly income

Other monthly debt

Down payment

Annual rate %

Term (years)

Max house price$404,392.24

Max monthly payment (PITI)$2,240.00

Max loan principal$354,392.24

Open

Property Tax

Assessed value × tax rate

Assessed value

Tax rate %

Annual tax$4,800.00

Monthly equivalent$400.00

Open

Refinance Break-Even

Months until refinance pays for itself

Total closing costs

Monthly savings (new vs old payment)

Break-even point22.222222 months

In years1.8518519

Open

Date & Time

// ages · differences · countdowns

Add or Subtract Days

Date + N days = result

Start date

Days to add (negative = subtract)

ResultSaturday, January 31, 2026

ISO date2026-01-31

Open

Age Calculator

Years · months · days between two dates

Date of birth

As of date

Age36 years, 0 months, 0 days

Total days13,149

Total months432

Open

Business Days

Weekdays between two dates (excludes Sat/Sun)

Start date

End date (inclusive)

Business days22

Total days (incl)31

Weekend days9

Open

Countdown / Days Until

Days remaining until a target date

From date

Target date

Days remaining365 days

Weeks52.14

Months (avg)11.99

Years (avg)1.00

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Date Difference

Days, weeks, months, years between two dates

Start date

End date

Difference364 days

Weeks52.00

Months (avg)11.96

Years (avg)1.00

Open

Weekday Lookup

Weekday name, ISO week, day of year

Date

DayThursday

Full dateThursday, January 1, 2026

ISO week1

Day of year1

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Nutrition

// energy needs · body composition · macros

Body Mass Index

BMI = mass / height²

SystemMetric (kg, cm)Imperial (lb, ft/in)

Weight (kg)

Height (cm)

BMI22.857143

CategoryNormal

Open

BMR & TDEE

Mifflin-St Jeor · daily energy needs

SexMaleFemale

Age (years)

Weight (kg)

Height (cm)

Activity levelSedentary (×1.2)Light (×1.375)Moderate (×1.55)Active (×1.725)Very active (×1.9)

BMR1648.75 kcal/day

TDEE2555.5625 kcal/day

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Body Fat (Navy)

US Navy circumference method

SexMaleFemale

Height (cm)

Waist (cm)

Neck (cm)

Body fat17.007719 %

Open

Calories from Macros

P/C 4 kcal/g · Fat 9 kcal/g · Alcohol 7 kcal/g

Protein (g)

Carbs (g)

Fat (g)

Alcohol (g)

Total1830 kcal

Protein400 kcal

Carbs800 kcal

Fat630 kcal

Alcohol0 kcal

Open

Glycemic Load

GL = (GI × carbs g) / 100

Glycemic Index (0–100)

Carbs per serving (g)

Glycemic load16.5 (Medium)

Open

Ideal Body Weight

Devine · Robinson · Miller · Hamwi

SexMaleFemale

Height (cm)

Ideal weight (kg)

Devine70.464567 kg

Robinson68.905512 kg

Miller68.745669 kg

Hamwi72.023622 kg

Open

Lean Body Mass

Boer formula (1984)

SexMaleFemale

Weight (kg)

Height (cm)

Lean body mass56.015 kg

Estimated fat mass13.985 kg

Open

Macros from Calories

Split daily calories by macronutrient ratios

Daily calories (kcal)

Protein %

Carbs %

Fat %

Macros (g/day)

Protein150 g

Carbs200 g

Fat66.666667 g

Open

Protein Needs

Daily protein target by activity goal

Body weight (kg)

Goal (g protein per kg)Sedentary / RDA (0.8)Light activity (1.2)Endurance training (1.4)General fitness (1.6)Strength athlete (1.8)Heavy training / fat loss (2.0)Bodybuilding (2.2)

Daily protein112 g

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Waist Ratios

Waist-to-hip · waist-to-height

SexMaleFemale

Waist (cm)

Hip (cm)

Height (cm)

Waist-to-hip0.89473684 (Healthy)

Waist-to-height0.48571429 (Healthy)

Open

Water Intake

35 mL/kg baseline + exercise adjustment

Body weight (kg)

Exercise (min/day)

Daily water2.805 L

Baseline (35 mL/kg)2450 mL

Activity bonus355 mL

US cups (≈240 mL)11.6875 cups

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Health & Fitness

// pace · heart rate · activity

Calories Burned (METs)

kcal = METs × weight (kg) × hours

ActivityWalking — moderate (3.0 MET)Walking — brisk (4.3 MET)Cycling — leisure 12 mph (6 MET)Cycling — moderate 14 mph (8 MET)Running — 10 min/mi (10 MET)Running — 8 min/mi (11.5 MET)Swimming — moderate (5.8 MET)Strength training — vigorous (5 MET)Hiking with pack (7.5 MET)HIIT (8.3 MET)Yoga — vigorous (3.5 MET)Soccer — recreational (7 MET)

Body weight (kg)

Duration (min)

Calories burned225.75 kcal

Rate301 kcal/h

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Heart Rate Zones

Tanaka max-HR (with optional Karvonen reserve)

Age (years)

Resting HR (bpm, optional)

Max HR ≈ 186 bpm · using HR reserve5 zones

Z1 50–60123–136 bpm

Z2 60–70136–148 bpm

Z3 70–80148–161 bpm

Z4 80–90161–173 bpm

Z5 90–100173–186 bpm

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Pregnancy Due Date

Naegele's rule (LMP + 280 days)

Last menstrual period

As of date

Estimated due dateThursday, October 8, 2026

Gestational age17 weeks, 5 days

Days until due156

Open

Running Pace

Pace per km/mi and average speed

UnitsKilometersMiles

Distance (km)

Hours

Minutes

Seconds

Pace5:00 /km · 8:03 /mi

Speed (km/h)12

Speed (mph)7.4564543

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Step Calories

Calories burned and distance walked

Steps

Body weight (kg)

Stride length (m, ~0.76 default)

Calories304.038 kcal

Distance7.62 km

Distance4.7348485 mi

Open

VO₂ max (Cooper Test)

Distance ran in 12 minutes → aerobic fitness

Distance in 12 min (meters)

VO₂ max42.367539 mL/(kg·min)

CategoryAbove average

Open

Construction & DIY

// paint · concrete · lumber

Concrete Volume

Slab volume in cubic yards / meters (+10% waste)

Length (ft)

Width (ft)

Depth (in)

Volume2.4691358 yd³

Cubic feet66.666667

Cubic meters1.8877898

Order with 10% waste2.7160494 yd³

Open

Lumber Board-Feet

BF = (thickness × width × length) ÷ 12

Thickness (in)

Width (in)

Length (ft)

Quantity

Board feet80 BF

Per piece8 BF

Open

Paint Coverage

Wall area × coats ÷ coverage rate = gallons

Total wall area (sqft)

Coverage (sqft / gallon)

Number of coats

Paint needed2.2857143 gal

Round up to3 gal

Open

Roof Pitch

Rise / run → ratio, angle, slope %

Rise (vertical)

Run (horizontal)

Pitch6/12

Angle26.565051°

Slope50 %

Ratio0.5

Open

Stair Calculator

Steps, riser height, and total run from total rise

Total rise (in, floor to floor)

Target riser height (in)

Tread depth (in)

Number of steps14

Riser height (actual)7.7142857 in

Total run143 in

2·riser + tread (target ≈ 25)26.428571 in

Open

Tile Calculator

Square tiles needed for a rectangular floor

Room length (ft)

Room width (ft)

Tile size (in, square)

Waste %

Tiles needed132 tiles

Exact (no waste)120

Floor area120 sqft

Open

Science

// physics · chemistry · optics

Density

ρ = m / V (g/cm³ if mass in g and volume in cm³)

Mass (m)

Volume (V)

Density2

Open

Gravitational PE

PE = m g h

Mass (kg)

Height (m)

Gravity g (m/s²)

Potential energy981 J

Open

Ideal Gas Law

P V = n R T (R = 8.314 J/(mol·K))

Solve forPressure (P)Volume (V)Moles (n)Temperature (T)

V (m³)

n (mol)

T (K)

Solved P101388.19 Pa

Open

Kinetic Energy

KE = ½ m v² (J, when m in kg and v in m/s)

Mass (kg)

Velocity (m/s)

Kinetic energy250 J

Open

Molarity

M = n / V (mol/L)

Moles of solute (n)

Volume of solution (L)

Molarity0.25 mol/L

Open

pH

pH = −log10[H⁺]

[H⁺] in mol/L

pH7

Open

Light: λ ↔ f

c = λ f (c = 299,792,458 m/s)

Solve forFrequency (f)Wavelength (λ)

Wavelength λ (m)

Result5.995849e+14 Hz

Open

Engineering

// circuits · mechanics

Electric Power

P = V · I (W)

Voltage (V)

Current (A)

Power600 W

Open

Fuel Economy

Distance and fuel consumed

Distance (mi)

Fuel (gal)

MPG25 mpg

L / 100 km9.4085833

km / L10.628593

Open

Ohm's Law

V = I · R

Solve forVoltage (V)Current (I)Resistance (R)

Current (A)

Resistance (Ω)

Solved V12 V

Open

Resistors in Parallel

1/R = 1/R₁ + 1/R₂ + 1/R₃

R₁ (Ω)

R₂ (Ω)

R₃ (Ω, optional)

Equivalent resistance68.75 Ω

Open

Voltage Divider

V_out = V_in · R₂ / (R₁ + R₂)

V_in (V)

R₁ (Ω)

R₂ (Ω)

V_out6.1875 V

Open