U.S. calculators for real rules. Global tools for everyday math.
Solveberry builds calculators whose answers change because a U.S. tax rule, wage law, retirement limit, government rate or effective date changes the calculation. The original global converter library remains available as a useful base layer.
Explore U.S. utilities How U.S. tools are sourced
Featured U.S. rules, rates & benefits calculators
These tools use cited U.S. government rules and effective dates rather than generic formulas with U.S. keywords added.
Federal Income Tax Bracket Calculator 2026
Estimate regular federal income tax, marginal bracket and effective rate using the official 2026 IRS schedules.
Retirement401(k) Contribution Calculator 2026
See the age-based employee deferral limit and the per-paycheck amount needed to reach it.
RetirementRoth IRA Contribution Calculator 2026
Estimate direct Roth IRA contribution room using filing status, MAGI, compensation and IRS phaseout rules.
WorkU.S. Overtime Pay Calculator
Apply the federal FLSA baseline for covered nonexempt hourly workers and see overtime pay after 40 hours.
MileageIRS Mileage Calculator 2026
Apply official IRS mileage rates, including the mid-year 2026 rate change.
RetirementRMD Calculator 2026
Estimate a 2026 required minimum distribution using the IRS Uniform Lifetime Table and prior-year balance.
Browse all 12 U.S. utilities · Read the U.S. source and update policy
Established converters with prior search evidence
The original calculator library stays live. These pages preserve existing index history and continue to solve distinct conversion tasks while new development shifts toward U.S.-specific utilities.
Ounces ↔ Pounds Converter
Convert ounces (oz) to pounds (lb) or pounds to ounces instantly. 16 oz = 1 lb exactly; 32 oz = 2 lb. Includes a conversion table and reverse conversion.
WeightKilograms ↔ Pounds Converter
Convert kilograms to pounds (kg to lbs) or pounds to kilograms (lbs to kg) using the exact international avoirdupois pound definition.
LengthMeters ↔ Feet Converter
Convert meters to feet or feet to meters using the exact international foot.
LengthCentimeters ↔ Inches Converter
Convert centimeters to inches or inches to centimeters using exactly 2.54 cm per inch.
CookingTablespoons ↔ Cups Converter
Convert tablespoons and cups with U.S., metric and Australian standards made explicit.
WeightGrams ↔ Ounces Converter
Convert grams and avoirdupois ounces using the exact international definition.
All global calculators and converters
Browse the complete legacy/base directory by task, or use the topic hubs below.
Ounces ↔ Pounds Converter
Convert ounces (oz) to pounds (lb) or pounds to ounces instantly. 16 oz = 1 lb exactly.
WeightKilograms ↔ Pounds Converter
Convert kilograms to pounds or pounds to kilograms using the exact international avoirdupois pound definition.
LengthMeters ↔ Feet Converter
Convert meters to feet or feet to meters using the exact international foot.
LengthCentimeters ↔ Inches Converter
Convert centimeters to inches or inches to centimeters using exactly 2.54 cm per inch.
CookingTablespoons ↔ Cups Converter
Convert tablespoons and cups with U.S., metric and Australian standards made explicit.
CookingMilliliters ↔ Cups Converter
Convert milliliters and cups while choosing a U.S. customary cup or 250 mL metric cup.
VolumeMilliliters ↔ Fluid Ounces Converter
Convert mL and fluid ounces while choosing U.S. customary or Imperial standards.
WeightGrams ↔ Ounces Converter
Convert grams and avoirdupois ounces using the exact international definition.
SpeedKPH ↔ MPH Converter
Convert kilometers per hour and miles per hour using the exact international mile definition.
LengthKilometers ↔ Miles Converter
Convert kilometers and miles using the exact international mile.
MathRatio Calculator
Simplify a ratio, compare its parts and see the decimal relationship between two non-zero values.
LengthMillimeters ↔ Inches Converter
Convert millimeters and inches using exactly 25.4 millimeters per inch.
TemperatureCelsius ↔ Fahrenheit Converter
Convert temperatures between Celsius and Fahrenheit in either direction.
VolumeLiters ↔ Gallons Converter
Convert liters and gallons while explicitly choosing U.S. liquid or Imperial gallons.
EverydayDiscount Calculator
Calculate sale price and amount saved from an original price and percentage discount.
Date & TimeAge Calculator
Calculate age between a birth date and selected date in completed years, months and days.
EverydayTip Calculator
Calculate tip amount, total bill and per-person share.
EducationGPA Calculator
Calculate a credit-weighted GPA from course grade-point values and credit hours.
FinanceMarkup Calculator
Calculate selling price and markup amount from cost and markup percentage.
FinanceMargin Calculator
Calculate gross profit, gross margin percentage and markup percentage.
LengthFeet ↔ Inches Converter
Convert feet and inches using exactly 12 inches per international foot.
Date & TimeTime Duration Calculator
Calculate elapsed hours and minutes between two clock times.
MathPercentage Calculator
Solve common percentage questions using transparent formulas.
EducationWeighted Grade Calculator
Calculate a weighted average from scores and weights.
EducationFinal Grade Calculator
Calculate the score needed on a final exam to reach a target overall grade.
AreaSquare Meters ↔ Square Feet Converter
Convert square meters and square feet using the international foot definition.
AreaAcres ↔ Hectares Converter
Convert international acres and hectares using exact definitions.
MathPercentage Increase / Decrease Calculator
Apply a chosen percentage increase or decrease to an original value.
MathPercentage Change Calculator
Calculate percentage change from an old value to a new value.
Date & TimeDays Between Dates Calculator
Calculate the whole-day difference between two calendar dates.
Browse by topic
Use a topic hub to move between related formulas, units and calculators.
Reference library
Deeper guides explain the standards, formulas, rule sources and edge cases behind calculator families.
U.S. Sources & Update Methodology
How Solveberry selects primary agencies, handles effective dates, records limitations and updates U.S. rule-based calculators.
Length Unit Standards
Exact definitions behind inches, feet, miles and metric length units.
Mass Unit Standards
International pound, avoirdupois ounce, kilogram and gram definitions.
Cooking Measurement Standards
U.S. customary, Imperial and metric cooking measurement standards.
Percentage & Finance Formula Guide
Percentage, percentage change, discount, tip, markup, margin and ratio formulas.
GPA, Grade & Date Calculation Guide
GPA, weighted-grade, final-grade, age, date-difference and time-duration formulas.
Speed, Temperature & Area Guide
Speed, temperature, floor-area and land-area conversion formulas.
Primary-source U.S. rules
U.S. tools cite agencies such as IRS, SSA, DOL, GSA and OPM and state the effective year or date used.
Useful first
Each indexed page solves a distinct user job rather than duplicating reverse-direction URLs or mass-generating thin pages.
Privacy-first calculation
Calculations run locally. Optional analytics measure product usage without transmitting calculator inputs or results.