Explore the calculator library by subject. Each category groups together tools for common real-world questions so visitors can quickly find the right calculator.
Start with the type of calculation you need.
Loans, interest, investing, household money and everyday financial decisions.
28 calculatorsPricing, profitability, sales, marketing and common business performance calculations.
20 calculatorsPercentages, algebra, geometry, fractions, statistics and general math problem solving.
33 calculatorsAges, date differences, workdays, schedules and everyday time calculations.
14 calculatorsMaterials, measurements and project estimates for common home and construction tasks.
28 calculatorsFuel, MPG, EV charging, tires, leases, towing and road-trip costs
12 calculatorsGrades, GPA, averages, test scores and classroom calculations for students and teachers.
8 calculatorsBMI, calories, pace, heart rate and other everyday health and fitness estimates.
14 calculatorsLength, weight, volume, area, temperature and other quick everyday unit conversions.
20 calculatorsGeometry, statistics, physics and chemistry calculators.
10 calculatorsZIP, geographic, cost-of-living, salary and currency tools.
10 calculatorsPopular tools from major sections of the site.
Loans, interest, investing, household money and everyday financial decisions.
Pricing, profitability, sales, marketing and common business performance calculations.
Percentages, algebra, geometry, fractions, statistics and general math problem solving.
Ages, date differences, workdays, schedules and everyday time calculations.
Fuel, trip, tire, lease, ownership and towing calculations.
ERICH Calculators organizes its free tools into clear subject areas such as money, math, home projects, school, health, business, dates and conversions. Every calculator has its own dedicated page with instructions, formulas, examples and related links.
Use our guides when you want more than just the answer.
A fixed-rate mortgage payment may stay the same from month to month, but the way that payment is divided between interest and principal changes over time. That changing split is the basic idea behind mortgage amortization.
Read guide →School & GradesA grade point average summarizes several course grades into one number. The exact rules can vary by school, but the basic calculation is straightforward once each grade is converted to grade points.
Read guide →Dates & TimeCounting business days sounds simple until weekends, holidays and inclusive date rules enter the picture. A clear method helps when planning deadlines, shipping windows, work schedules and response periods.
Read guide →Home & ConstructionConcrete is normally ordered by volume, so the key is to convert the dimensions of a slab, footing or other pour into cubic yards. A small measurement error can become expensive on a larger project.
Read guide →Choose Money & Finance if the result is a payment, interest amount or savings projection. Choose Business when comparing margins, pricing, labor costs or advertising performance. For time-card totals and deadlines, start with Dates & Time; for areas, materials or project quantities, start with Home & Construction. Math and Conversions are better starting points when the question is a formula or a change in units. Each category links to calculators and supporting examples so you can verify what the result means.