Date & Time
Add or subtract time from a date
time-adder-subtractorDate & Time
Format time duration into various human-readable formats
time-duration-formatterMath & Numbers
Calculate trigonometric functions (sin, cos, tan)
trigonometry-calculatorFinance
Split bills by items with individual amounts and custom tip percentages per person
tip-calculator-splitFinance
Calculate VAT (Value Added Tax) for purchases and sales
vat-calculatorFinance
Estimate investment doubling time using the Rule of 72 and other investment rules
rule-of-72Math & Numbers
Calculate engineering stress σ = F/A and engineering strain ε = ΔL/L₀ under uniaxial load. Choose what to solve: for stress, enter force F (N) and cross-section area A (mm²) → result in MPa; for strain, enter original length L₀ and elongation ΔL (negative for compression) → dimensionless ratio. Units are self-consistent (N, mm) so stress comes out directly in MPa.
stress-strain-calculatorFinance
Calculate student loan repayment with an optional grace period and subsidized/unsubsidized interest. Unsubsidized loans accrue interest during the grace period that capitalizes into principal; subsidized loans do not. Shows monthly payment, total interest, total repayment, a balance curve, and a yearly breakdown.
student-loan-calculatorMath & Numbers
Convert stone to pounds with configurable decimal precision
stone-to-lbMath & Numbers
Convert stone to kilograms with configurable decimal precision
stone-to-kgMath & Numbers
Estimate total study hours, daily study targets, and schedule feasibility from topics, difficulty, and available time
study-time-calculatorMath & Numbers
Calculate the standard error of the mean from raw sample values or summary statistics
standard-error-calculator