Free · Instant results · Formulas explained
Fast answers to every calculation.
Speedy Calculator gives instant, accurate results for money, health, science and everyday life — with the formula, a worked example and sources for every tool.
3232 calculators · 13 categories
Browse by category
All calculators →
Chemistry
109 calculators
Construction
145 calculators
Conversion
317 calculators
Ecology
9 calculators
Everyday Life
218 calculators
Finance
557 calculators
Food & Cooking
97 calculators
Health
359 calculators
Math
416 calculators
Other
220 calculators
Physics
482 calculators
Sports
103 calculators
Statistics
200 calculators
Popular calculators
Atomic Mass Calculator
The atomic mass calculator estimates the mass of a single atom from its numbers of protons…Average Atomic Mass Calculator
The average atomic mass calculator weights each isotope’s mass by its natural abundance to give the…Bond Order Calculator
The bond order calculator finds the bond order from the numbers of bonding and antibonding electrons,…Chemical Name Calculator
The chemical name calculator turns a formula into its systematic name – ionic compounds with Roman…Effective Nuclear Charge Calculator
The effective nuclear charge calculator applies Slater’s rules to any element or ion: pick the electron’s…Electron Configuration Calculator
The electron configuration calculator writes the ground-state electron configuration of any element or ion – the…Electron Configuration Quiz
The electron configuration quiz gives you endless practice: write full or noble-gas configurations of random elements…Formulas shown
Every result comes with the equation behind it and a worked example.
Work backwards
Type the answer you want and the calculator solves for the missing input.
Any unit
Switch metric and imperial units on any field without losing your values.
Sourced
Methods reference published standards, studies and official guidance.
Latest guides
APR vs APY: What’s the Difference and How to Convert Them
APR leaves out compounding, APY includes it. See the conversion formulas, why banks quote APY on savings and APR on loans, and…
How to Calculate GPA: Weighted, Unweighted and Cumulative (With Examples)
The credit-weighted formula behind every GPA, worked through a real 15-credit semester, plus weighted vs unweighted scales and how fast a cumulative…
How Many Calories Should I Eat? BMR, TDEE and Your Real Number
Your calorie target starts with BMR and TDEE, but the real number comes from adjusting after a few weeks. A step-by-step method…