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Illustration of ziffaro's calculators — average, surface area, daily balance and unit converter tools.

Finance

Free finance calculators for the money questions that come up most — paychecks, taxes, loans, savings and more. Instant, clear breakdowns, no signup.

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Compound Interest Calculator
Growth with contributions
Auto Loan Calculator
Car loan payment & interest
Paycheck Calculator
Take-home pay after tax
Car Payment Calculator
Monthly car payment
Tip Calculator
Tip, total & split
401(k) Calculator
Retirement balance projection

Business

Free invoice, estimate and document generators for freelancers and small businesses — fill in, download a PDF, done.

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Invoice Generator
Make & download an invoice
Time Card Calculator
Weekly hours & pay
Estimate Generator
Make & download an estimate
Receipt Generator
Itemized receipt of payment
Purchase Order Generator
Make & download a PO
NDA Generator
Mutual or one-way NDA

Home & Construction

Free home and construction calculators — square footage, materials like gravel, asphalt and lumber, plus framing and wiring. Instant, no signup.

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Square Footage Calculator
Area in square feet
Voltage Drop Calculator
Wire voltage drop %
Board Foot Calculator
Lumber board feet
Asphalt Calculator
Asphalt tonnage & cost
Conduit Fill Calculator
NEC conduit fill %
Gravel Calculator
Gravel yards & tons

Health

Free health calculators for everyday numbers — A1C, BMI, body fat, calories and more — with clear, source-backed estimates. Instant, no signup.

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BMI Calculator
Body Mass Index + category
Calorie Calculator
Daily calories for your goal
BMR Calculator
Basal metabolic rate
TDEE Calculator
Maintenance calories
Body Fat Calculator
U.S. Navy method
Ideal Weight Calculator
Devine, Hamwi & BMI range

Math

Free math calculators that solve averages, percentages, areas and more in seconds — with the steps shown, so they’re handy for school and work.

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Percentage Calculator
% of, is what %, % change
Average Calculator
Mean, median, weighted, %
Proportion Calculator
Solve a/b = c/d
Mean Median Mode Calculator
Mean, median, mode & range
GCF Calculator
Greatest common factor
Cubic Feet Calculator
Volume in cubic feet

Citation Generators

Free citation generators for AMA, Chicago, IEEE, ACS, Turabian and CSE styles — format your references in seconds.

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APA Citation Generator
APA-style references (7th ed.)
MLA Citation Generator
MLA-style references (9th ed.)
AMA Citation Generator
AMA-style references
Chicago Citation Generator
Chicago author-date
IEEE Citation Generator
IEEE references
ACS Citation Generator
ACS references

Converters

Convert units and values both ways in seconds — length, weight, temperature and more. Free, instant and accurate, with no signup or clutter.

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Length Converter
mm, cm, m, in, ft, mi…
Weight Converter
g, kg, oz, lb, st…
Temperature Converter
Celsius, Fahrenheit, Kelvin
Ring Size Calculator
Diameter to US, UK & EU

Generators

Free generators for names, usernames, business names, text and more — produced in a click. Generate as many as you like, instant, no signup.

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Password Generator
Strong random passwords
Username Generator
Unique username ideas
Business Name Generator
Brand name ideas
Xbox Gamertag Generator
Cool gamertag ideas

Time

Free time and date calculators — work out hours between times, average durations and countdowns in seconds, with the steps shown. No signup.

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Chronological Age Calculator
Exact age in y/m/d
Deadline Calculator
Date plus days
Age Gap Calculator
Age difference between two
Average Time Calculator
Mean of multiple times

Why ziffaro

Tools provide carefully built estimates for general information only — not professional advice.