Calculators

Age Calculator

Calculate exact age in years, months, and days from a date of birth.

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Hours Calculator

Calculate the hours and minutes between two times.

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Twitter Ad Revenue Calculator

Estimate your potential Twitter/X ad revenue from impressions.

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Tip Calculator

Calculate restaurant tips and split the bill between people instantly.

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EMI / Loan Calculator

Calculate monthly EMI, total interest and full amortization for any loan.

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Compound Interest Calculator

Project savings growth with compounding, regular contributions and a year-by-year breakdown.

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Currency Converter

Convert between 30+ world currencies with live ECB exchange rates.

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Pet Age Calculator

Convert your dog or cat's age into human years using breed-size adjusted formulas.

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Sleep Cycle Calculator

Find the best bedtime or wake time based on 90-minute REM sleep cycles.

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Caffeine Half-Life Calculator

Track how much caffeine is in your bloodstream over 24 hours and find your safe-to-sleep time.

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BAC Calculator

Estimate blood alcohol content using the Widmark formula based on weight, gender and drinks.

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Recipe Scaler

Scale any recipe up or down by changing the serving size - auto-detects measurements and fractions.

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ROI Calculator

Calculate return on investment for any project, ad campaign, or asset purchase - enter cost and final value, get ROI%, gain, and annualized...

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NPV and IRR Calculator

Discounted cash flow analysis - paste a year-by-year cash flow stream and get the net present value and internal rate of return at your chos...

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Payback Period Calculator

How long until cumulative cash flows recover the initial investment - simple and discounted payback with year-by-year running totals.

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Break-Even Calculator

How many units (or revenue dollars) you need to sell to cover fixed costs. Returns break-even units, revenue, and contribution-margin breakd...

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Markup vs Margin Calculator

Convert between markup (% over cost) and margin (% of price). Side-by-side calculation that prevents the most common pricing mistake.

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CAC, LTV & LTV:CAC Calculator

SaaS unit economics in one place - customer acquisition cost, lifetime value, and the LTV:CAC ratio that signals whether the business scales...

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Burn Rate & Runway Calculator

Monthly cash burn and how long your runway lasts. Enter cash balance and recent expenses; get net burn, gross burn, and runway in months.

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Mortgage Calculator

Full mortgage payment breakdown - monthly P&I, total interest, and a year-by-year amortization schedule showing principal vs interest split.

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Loan Affordability Calculator

What loan amount can you actually afford? Enter income, debt, rate, and term; the tool back-solves for the maximum loan within lender DTI li...

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Take-Home Pay Calculator

Convert gross pay to net pay - federal tax, FICA, state tax, and pre-tax deductions like 401(k) and health insurance, per paycheck and per y...

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CPM, CPC & CPA Calculator

Three ad-spend metrics in one place - cost per thousand impressions, cost per click, and cost per acquisition. Convert between them in eithe...

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ROAS Calculator

Return on ad spend - revenue per dollar of ad cost. Returns ROAS as both ratio and percentage, plus breakeven ROAS based on your gross margi...

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A/B Test Significance Calculator

Did your A/B test actually win? Returns p-value, statistical significance, and minimum sample size for 95% confidence.

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Conversion Funnel Calculator

Multi-step funnel drop-off analyzer. Enter users at each stage; the tool shows step rates, biggest drop-off, and impact of fixing each step.

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Email Marketing Metrics Calculator

Open rate, CTR, click-to-open rate, unsubscribe rate, bounce rate, and revenue-per-email. Every email metric in one view with industry bench...

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Rent vs Buy Calculator

Should you rent or buy? Compares 5/10/30-year cost of renting vs owning, including taxes, maintenance, and opportunity cost.

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Refinance Break-Even Calculator

Should you refinance? Calculates how many months until refinance savings cover closing costs, factoring in new rate and term.

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Cap Rate Calculator

Capitalization rate for real estate - NOI ÷ property value. Returns cap rate, gross rent multiplier, and cash-on-cash return.

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Loan-to-Value Ratio Calculator

LTV ratio for mortgage applications. Flags whether PMI is required and shows the down payment needed for 80%, 90%, 95% thresholds.

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Hourly to Annual Salary Calculator

Convert between hourly wage and annual salary, accounting for hours worked, holidays, vacation, and unpaid time off.

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Overtime Pay Calculator

Federal time-and-a-half overtime. Supports state-specific rules where overtime kicks in at 8 hours/day instead of 40 hours/week.

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PTO & Vacation Accrual Calculator

How many vacation/PTO days you have accrued. Returns current balance, accrual per pay period, and projected year-end balance.

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Fuel Cost Calculator

Trip fuel cost based on MPG, distance, and gas price. Supports US (MPG) and metric (L/100km). Compare vehicles or estimate annual fuel spend...

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GST Calculator

GST exclusive means the price you see does not include tax, and GST is added on top. GST inclusive means the price already contains the tax,...

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Sales Tax Calculator

Sales tax is a single-stage tax charged only at the final retail sale, common in the United States. VAT and GST are multi-stage taxes collec...

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Discount Calculator

Multiply the original price by (1 minus the discount as a decimal). A 25 percent discount on $80 means 80 times 0.75, which equals $60. The...

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Percentage Change Calculator

The formula is (new value minus old value) divided by old value, times 100. If something went from 50 to 75, the change is 25 divided by 50,...

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BMI Calculator

BMI equals weight in kilograms divided by height in meters squared. For imperial units, it is weight in pounds times 703, divided by height...

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Salary Calculator

Divide annual salary by the number of working hours per year. The standard assumption is 40 hours times 52 weeks, or 2,080 hours. So $52,000...

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Investment Calculator

Compound interest is interest earned on both your original principal and on previously earned interest. Over time it accelerates growth dram...

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Revenue Growth Calculator

Revenue growth percentage equals (new revenue minus old revenue) divided by old revenue, times 100. If a business earned $100,000 last year...

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Calorie Calculator

The tool uses the Mifflin-St Jeor equation to estimate your basal metabolic rate (BMR), then multiplies it by an activity factor to give Tot...

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BMR Calculator

Basal Metabolic Rate is the energy your body uses to keep you alive at complete rest: breathing, circulating blood, regulating temperature,...

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Body Fat Percentage

It uses circumference measurements: neck and waist for men, plus hips for women, combined with height. The formula was developed by the Navy...

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Ideal Weight Calculator

Devine (1974), Hamwi (1964), Robinson (1983), and Miller (1983) are four widely cited formulas, each developed for a different purpose. Devi...

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Macros Calculator

It first finds your daily calorie target based on goal (cut, maintain, or bulk), then assigns a percentage to protein, carbs, and fat. A com...

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Pregnancy Due Date

The standard method is Naegele's rule: take the first day of your last menstrual period (LMP), add 280 days (40 weeks), and that is the esti...

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Ovulation Calculator

It assumes ovulation occurs 14 days before your next expected period. So for a 28-day cycle ovulation is on day 14, for a 30-day cycle it is...

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Heart Rate Zones

The calculator first estimates your maximum heart rate (MHR) using 220 minus age, then applies the Karvonen formula with your resting heart...

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Water Intake Calculator

The calculator uses your body weight as the main input (typically 30 to 35 ml per kilogram, or about half an ounce per pound) and adds extra...

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Running Pace Calculator

It converts between three values: pace (minutes per kilometer or mile), total time, and distance. Enter any two and it solves for the third....

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Mean Median Mode

The mean is the arithmetic average: add all values and divide by the count. The median is the middle value once the list is sorted, or the a...

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Standard Deviation

Population standard deviation divides by N, while sample standard deviation divides by N minus 1. Use the population formula when your data...

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Variance Calculator

Variance is the average of the squared deviations from the mean. Standard deviation is just the square root of variance. They measure the sa...

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Probability Calculator

Divide the number of favourable outcomes by the total number of equally likely outcomes. Rolling a 4 on a fair die is 1 divided by 6, or abo...

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Permutation Combination

Permutations care about order; combinations do not. Picking a president, vice-president, and secretary from a club is a permutation because...

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Quadratic Equation Solver

For an equation ax^2 + bx + c = 0, the roots are x equals minus b plus or minus the square root of (b squared minus 4ac), all divided by 2a....

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Linear Equation Solver

For two equations a1*x + b1*y = c1 and a2*x + b2*y = c2, Cramer's rule expresses x and y as ratios of determinants. The denominator is the d...

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Fraction Calculator

It finds a common denominator (the product of the two denominators is always safe), rewrites each fraction with that denominator, adds the n...

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Prime Number Checker

A prime is a whole number greater than 1 that has exactly two divisors: 1 and itself. The first few are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29....

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GCD LCM Calculator

GCD (greatest common divisor) is the largest number that divides both inputs. LCM (least common multiple) is the smallest number that both i...

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Triangle Calculator

You can solve any triangle from three known pieces, as long as at least one is a side. Common cases are SSS (three sides), SAS (two sides an...

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Logarithm Calculator

A logarithm is the inverse of exponentiation. Log base b of x asks the question: what power do I raise b to in order to get x? Log base 10 o...

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Meeting Cost Calculator

Calculate the real $ cost of a meeting from attendee salaries, duration, and an overhead multiplier.

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Subscription Cost Auditor

Audit your monthly subscriptions - see total spend, per-hour cost, and which subs to cancel. Data stays in your browser.

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