PocketKit
Free online calculators
Use free calculators for loans, mortgage refinancing, percentages, discounts, tips, sales tax, compound interest, GPA, BMR and exchange rates.
What can you do with these tools?
PocketKit calculators cover personal finance, purchases, study and health estimates. Each page explains its formula, units and limitations. Loan, tax, GPA and health results support comparison and planning but do not replace lender quotes, official transcripts, tax advice or medical guidance. Live exchange rates require a network connection; basic calculations generally run in the current browser.
Start here
Core tools
Percentage Calculator
X% of Y, ratios and percent change
Loan Calculator
Monthly payment, total interest and full amortization
Mortgage Refinance Calculator
Compare your current mortgage with refinance options to find monthly savings, total interest saved, and the break-even period.
Compound Interest Calculator
Compound growth with optional monthly contributions
Sales Tax Calculator
US state sales tax, with tax-inclusive reverse mode
Discount Calculator
Sale price and savings, with stacked discounts and tax
GPA Calculator
Calculate overall and semester GPA with course grades, credits and various grading scales (4.0, 4.3, 5.0, WES).
BMR & TDEE Calculator
Compute Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE) with Mifflin-St Jeor & Harris-Benedict formulas.
Tip Calculator
Tip and total by rate, split across people
Keep exploring
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Decision guide
Why calculator results can differ
| Type | Key variables | Verify |
|---|---|---|
| Loans and compound interest | Rate, term, compounding and fees | Loan Calculator |
| Percentages and discounts | Base value, direction and rounding | Percentage Calculator |
| GPA | Credit weighting and institutional scale | GPA Calculator |
| BMR | Formula, age, weight and activity factor | BMR & TDEE Calculator |
FAQ
Frequently asked questions
Can results be used as formal financial or medical advice?
No. Results use your inputs and the formula stated on the page and are intended for estimation and comparison. Use authoritative records and professional advice for loans, taxes, grades or health decisions.
Why can results differ from a bank, school or another calculator?
Formulas, rounding, compounding frequency, included fees, grading rules and activity factors can differ. Compare the method shown on the page with the rules of the relevant institution.
Do calculators store entered values?
Basic calculations generally run in the current browser without sending inputs to the PocketKit API. Live exchange rates require a network request. Check each tool page for its specific data-handling label.