Our Md Calculators

Calculate the exact time difference between two dates, in years, months, days, weeks, hours, minutes, and seconds.

Calculate your age in years, months, and days based on your birth date.

Convert your dog's age to human years, and calculate their age in dog years.

Add or subtract time durations in days, hours, minutes, and seconds.

Calculate the duration between two specific times, including hours, minutes, and seconds.

Convert days, hours, minutes, and seconds into a single decimal value for easy calculations.

Calculate total work hours, including breaks and overtime, for your timesheet.

A precise stopwatch with millisecond accuracy, perfect for timing events in games, sports, and daily tasks.

Determine if a year is a leap year quickly and accurately.

Convert dates between Gregorian and Lunar calendars.

Convert dates from the Islamic Hijri calendar to the Gregorian calendar.

Convert dates from Gregorian to Hijri and vice versa, supporting various Islamic calendar standards.

Calculate the number of days between two specified dates quickly and accurately.

Add or subtract days, months, or years from a given date to find a future or past date.

Perform various calculations involving dates, such as adding or subtracting days, and finding the day of the week.

Estimate how long a book or article takes from word count or pages, your reading speed (WPM), and optional daily minutes to see days to finish.

Rough wake-time targets from bedtime, or bed-time ideas from your alarm, using adjustable cycle length (often 90 minutes). Not medical advice.

Add many clip lengths in one go (MM:SS, H:MM:SS, or seconds per line). Great for podcasts, edits, and playlists.

Turn top/bottom/side margin percentages into pixel insets for 9:16 vertical video (Shorts, Reels, etc.). Planning helper—not official platform specs.

Rough cat years ↔ human years using a common simplified chart. Decimal ages supported—not veterinary advice.

Estimate doubling time from a growth rate, or implied rate to double in N years. Educational mental math only.

Get ISO week number and ISO year for any calendar date (ISO 8601, week starts Monday).

Count Monday–Friday days between two dates (weekends only; no public holidays).

Words plus words-per-minute to estimate voice-over or audiobook duration.

Convert stitches and rows per 10 cm ↔ per inch for pattern scaling.

Match hook diameter in mm to common US letter / number labels (approximate chart).

Pixels and DPI to print width in inches; handy for photo prints.

Given width and ratio W:H, compute height (or scale both sides by a factor).

Bitrate and duration to estimated file size (Mbps, minutes).

File size and download speed to approximate transfer time.

Show current date and time in two IANA time zones side by side.

2–5 IANA zones, one calendar day, shared local office hours—see which UTC hour starts put everyone in-window (optional Mon–Fri).

Week number since a semester start date (weeks aligned to Mondays).

Weighted grades: what you need on the final to reach a target course grade.

Enter grade points and credits per line; computes weighted GPA on a 4.0-style scale.

Hourly rate × hours per week × 52 (simple, no tax).

Target annual income, billable weeks/hours, and buffer % to a suggested hourly rate.

Coffee grounds (g) and ratio 1:N to total brew water in ml.

Flour weight and ingredient % of flour to ingredient grams.

Body weight (kg) × 0.033 L rough estimate—not medical advice.

Minutes and seconds per km to km/h and approximate mile pace.

Race distance and goal time → average pace per km and per-5 km cumulative splits.

Wall area, coverage per gallon, and coats → gallons needed (rounded up).

Length × width (ft) × depth (inches) to cubic yards for a rectangular slab.

Room floor area, square tile size, and waste % → approximate tile count.

Lawn area and coverage per bag → number of bags (rounded up).

Paste segment durations per line; get cumulative chapter markers for descriptions.

Bill amount, tip percent, and party size—tip, total with tip, and per person.

Body mass index from weight (kg) and height (cm)—adult screening categories only.

Original price and percent off—sale price and savings.

Miles, MPG, and price per gallon—gallons used and trip fuel cost (US units).

Loan amount, annual rate, and years—estimated monthly principal & interest (excludes tax/insurance).

Principal, annual rate, years, and compounding periods per year—future value.

Old value vs new value—absolute change and relative percent change.

Cost plus markup % on cost—selling price and margin % of selling price.

Pre-tax subtotal and tax rate—tax amount and total with tax.

Rectangle in feet—length × width to square feet (and approximate square meters).

Principal, annual rate %, and years—interest and total repayment.

Fixed costs, variable cost per unit, and price—units needed to break even.

Monthly income and max rent % of income—rule-of-thumb rent cap.

Enter decimal odds (e.g. 2.50)—naïve implied win % (no vig removed).

Balance, APR, and fixed monthly payment—months to payoff and total interest (simplified).

Starting value, ending value, and years—compound annual growth rate %.

Monthly contribution, nominal annual return %, and years—future value and total contributed.

Present value, annual inflation %, and years—future nominal value and multiplier.

Principal, APR %, and term in months—monthly payment and total interest (amortizing).

Affordable monthly payment, APR %, and years—estimate maximum loan principal.

kWh used and price per kWh—total electricity cost.

Solve a:b = c:x for x (cross-multiply: x = b×c÷a).

Decimal hours or total minutes to hours-and-minutes text.

Integer range, how many numbers, optional unique draws (≤ range size).

US MPG ↔ liters per 100 km using a fixed conversion constant.

Total price and quantity—cost per unit; optional second product comparison.

Revenue and cost—gross profit dollars and profit margin % on revenue.

Sale amount and commission rate—fee and net to seller.

List price and sale price—discount percent and dollars saved.

Centimeters ↔ feet and inches for body height planning.

Convert Arabic numbers to Roman numerals and parse common Roman strings back.

Years, months, and days between two birth dates (calendar-based).

Base hourly rate plus regular and overtime hours—overtime paid at 1.5× for a rough gross total.

Target balance, monthly deposit, and nominal annual rate—months to reach goal (simplified).

Upfront cost and constant yearly benefit—simple payback time in years.

Air temperature and wind speed—approximate wind-chill index (educational).

Convert a temperature between °C and °F.

Kilometers ↔ statute miles using the standard conversion constant.

Convert mass between pounds and kilograms.

Liters ↔ US liquid gallons (not UK imperial).

Total bill, headcount, and optional tip percent—per person share.

If a value grew by P% to reach V, find the original base before the increase.

Two value–weight pairs—weighted mean (e.g. grades and credits).

Radius → area πr² and circumference 2πr in consistent units.

Two legs of a right triangle—hypotenuse and area.

Hourly rate × hours per week × (52÷12)—rough gross monthly (before tax).

What is P% of N? Quick multiply N×P÷100.

Tax-included total and rate—net price and tax portion.

Two successive percent-off steps—final price and equivalent single discount.

Principal square root for non-negative real x.

Air temperature °C and RH%—approximate dew point for planning.

Length conversion using 1 in = 2.54 cm.

Meters and feet using a fixed conversion constant.

1 acre = 43,560 sq ft—common US land unit helper.

Convert decimal degrees to degrees, minutes, seconds.

Split a whole second count into hours, minutes, seconds.

Character pool size and length—approximate bits of entropy.

Greatest common divisor and least common multiple of two integers.

Principal and APR—monthly interest-only payment (no amortization).

Regular, time-and-a-half, and double-time hours in one gross estimate.

Physical length in cm and DPI—pixel count along that edge.

Small factorials for combinatorics homework checks.

Binomial coefficient C(n,r) with a stable multiplicative formula.

Given long or short side, find the other for φ ≈ 1.618 proportions.

Length × width × height in consistent units.

π r² h for a right circular cylinder.

(4/3) π r³ from radius.

Idealized (1/2)^(t / t½) fraction remaining for teaching sketches.

Mifflin–St Jeor resting metabolic rate from weight, height, age, and sex.

Loan amount and property value—LTV % for quick mortgage context.

Monthly debt payments and gross monthly income—DTI %.

Hits and at-bats—batting average to three decimals.

Total bases and at-bats—SLG = TB / AB.

Two (x,y) pairs—slope m (vertical line excluded).

Average of coordinates—center between two points.

US liquid quarts and liters (not imperial UK quarts).

Avoirdupois ounces and grams (mass, not fl oz).

Scientific temperature offset: K and °C.

What percent is A of B? (A / B) × 100.

Meters per second and kilometers per hour (× 3.6).

Mass and molar mass—amount in moles (n = m / M).

Moles of solute and volume in liters—molarity M.

Stock molarity, stock volume, target molarity—final volume V₂.

Gross annual pay ÷ 12 (plus rough weekly from ÷ 52).

Binary string of 0s and 1s to a decimal integer.

Non-negative integers up to about 2²⁰ to binary text.

Total decimal hours split into 24-hour days and remainder.

Run length and spacing—post count with a post at each end.

Length, width, depth in feet—rough US gallons of water.

Total rise and target riser height—step count and equalized riser.

Hex string (optional 0x) to a decimal integer.

Non-negative integers up to 2³²−1 to uppercase hex.

Base-8 digit string to a decimal integer.

Non-negative integers up to 2³¹−1 to octal text.

International yard (0.9144 m) conversion both ways.

Land area: international acre and hectare.

Bed area, depth in inches, bag size in ft³—bags to buy.

Length, width, depth in feet—cubic yards of fill.

Temperature and humidity—feels-like heat index estimate.

Wall run, height, roll width and length—rolls needed.

Two diameters in inches—each area and size ratio.

Lawn area and ft² per roll—how many sod pieces to order.

Floor or land area between square meters and square feet.

International nautical mile (1.852 km) both ways.

Angle conversion using π (exact factor).

Common logarithm for positive x.

Exponent x—ten to the x power (limited range).

Feet per second and miles per hour—speed conversion.

Area, sheet size (e.g. 32 ft²), waste %—sheets to buy.

Signed degrees plus minutes and seconds to decimal °.

Hz and seconds—f = 1/T for periodic signals.

Frequency in Hz—λ = c / f in meters and nm.

Vin, R1, R2—no-load output at the divider tap.

Two resistors in parallel—equivalent Ω.

Solve for V, I, or R from the other two values.

Vs, Vf, target mA—ballast R and resistor power.

Byte count using binary 1024 prefixes.

Diagonal inches (16∶9)—rough min–max distance in feet.

mAh capacity and average mA load—ideal hours.

RPM and diameter in inches—rim speed ft/min and m/s.

Pressure between bar and pounds per square inch.

Kilopascals and psi—pressure conversion.

UK stones and extra pounds to kilograms.

Food energy kilocalories and kilojoules (×4.184).

Shares held and split factor—count after split.

US gallons and GPM—hours to fill at steady flow.

ft³ needed and ft³ per bag—bags to buy (rounded up).

Up to three insulation layers—approximate total R.

Impressions and CPM—simple media cost estimate.

Monthly rent and leased square feet—$/ft²/month.

Japanese tsubo and square meters for property area.

Sum of three bag dimensions vs airline linear limit.

Tempo to quarter-note length for delay/MIDI math.

mm on plan at 1:N scale to real meters.

People, hourly rate, minutes—rough meeting cost.

Width, drop, fullness, panels—simple fabric area.

Tank liters and change percent—liters to replace.

EU-style consumption, km, price per liter—trip cost.

Daily pay × payout days—simple gross estimate.

Weight and reps—estimated one-rep max.

Bed size and spacing—plant count on a grid.

Page count double-sided—physical sheets needed.

FPS and duration in seconds—total frames.

Monthly rent and square meters—€/m² style density.

Available time, work and break blocks—cycle count.

0–255 channels—quick luma value.

Display px and video aspect—inner size and bars.

Word count and words per page—pages to print.

Gauge per 10 cm and width—stitches to cast on.

Net amount and VAT %—gross and tax portion.

Tonnes and kilograms—SI mass conversion.

Albumin-adjusted serum calcium (mg/dL or mmol/L)—multilingual medical-style tool.

Rule of three: direct, inverse, and percent proportions — multilingual (German default, English and more).