Free Tools
100 free professional calculators and decision support for researchers, analysts, data scientists, students, academics, and operations, quality, finance, HR, time and workforce professionals — research planning, statistical testing, data analysis, capacity and staffing, service levels, quality, and financial analysis. No account required.
Professional & Research Guides
General calculators12 tools
Percentage Calculator
Percentages, increases, decreases, changes and discounts — fast, free and accurate.
Average Calculator
Find the arithmetic mean of any list of numbers.
Ratio Calculator
Simplify a ratio to its lowest terms.
Proportion Calculator
Solve a ÷ b = c ÷ x for the missing term.
Time Duration Calculator
Find hours and minutes between two times.
Date Difference Calculator
Count calendar days between two dates.
Percentage Change Calculator
Find the percent increase or decrease between two values.
Age Calculator
Find exact age in years, months and days from a birth date.
Business Days Calculator
Count weekdays between two dates for deadline planning.
Time Zone Converter
Convert a date and time between time zones, with DST handled.
Weighted Average Calculator
Find the mean of values that count by their own weight.
Rounding & Significant Figures Calculator
Round a number to decimal places or significant figures.
Research tools14 tools
Sample Size Calculator
Find how many respondents you need for accurate survey results.
Margin of Error Calculator
Estimate the sampling error in your survey results.
Response Rate Calculator
Measure how many invited people completed your survey.
Completion Rate Calculator
Measure how many started surveys were finished.
Incidence Rate Calculator
Find the share of screened respondents who qualify.
Sampling Interval Calculator
Pick every k-th unit for systematic sampling.
Panel Attrition Rate Calculator
Find what share of a research panel disengaged over a period.
Cost Per Complete Calculator
Find the average fieldwork cost per completed interview.
Likert Scale Analysis Calculator
Summarize a 5-point Likert distribution: mean, top-2-box, bottom-2-box.
Quota Sampling Calculator
Find how many respondents to recruit from one stratum.
Stratified Sampling Calculator
Find a stratum's proportional sample size.
Non-Response Bias Estimator
Estimate how much non-response may be skewing your results.
Top-Box Score Calculator
Find the share choosing the highest rating (or top two).
Survey Length & Completion Time Estimator
Predict how long a survey will take from its question mix.
Operations tools16 tools
Workforce Utilization Calculator
See how much of your team's available time is productive.
Capacity Calculator
Estimate how many tasks a team can complete.
Productivity Calculator
Measure output per hour of work, in any unit.
SLA Compliance Calculator
See how many cases meet their service level agreement.
Turnaround Time Calculator
Measure elapsed time from start to completion.
Cost Per Task Calculator
Find the average operational cost of a task.
FTE Calculator
Convert mixed full-time and part-time hours into one staffing unit.
Erlang C Staffing Calculator
Find wait probability, speed of answer and service level for a queue.
Shift Coverage Calculator
Find what percentage of required staff are scheduled.
Staffing Ratio Calculator
Find how many units each staff member is responsible for.
On-Time Delivery Rate Calculator
Find what percentage of deliveries arrived on time.
Backlog Clearance Time Calculator
Find how many days it will take to clear a backlog.
Absenteeism Rate Calculator
Find what percentage of scheduled time was lost to absence.
Schedule Adherence Calculator
Find what percentage of scheduled time was spent in status.
Queue Abandonment Rate Calculator
Find what percentage of callers hung up before service.
Cycle Time Calculator
Find the average time to move one unit through a process.
Business & finance tools10 tools
Cost Per Hire Calculator
Find the average recruiting cost per hire.
Break-Even Point Calculator
Find how many units you need to sell to cover fixed costs.
ROI Calculator
Find the percentage return from an investment.
CAGR Calculator
Find the smoothed annual growth rate between two values.
Profit Margin Calculator
Find gross profit and profit margin percentage.
Markup vs Margin Calculator
See markup and margin side by side from cost and price.
Budget Variance Calculator
Find how far actual spend deviated from budget.
Freelancer/Consultant Hourly Rate Calculator
Find the hourly rate you need to hit your income goal.
Overtime Cost Calculator
Find the total cost of overtime hours.
Late Payment / Invoice Fee Calculator
Estimate interest owed on an overdue invoice.
Quality & compliance tools8 tools
AQL Sampling Calculator
Find the sample size and Ac/Re numbers for a lot inspection.
Process Capability (Cp/Cpk) Calculator
Find Cp, Cpu, Cpl and Cpk for a process.
DPMO Defect Rate Calculator
Find defects per million opportunities and sigma level.
Cohen's Kappa Calculator
Measure inter-rater agreement corrected for chance.
First Pass Yield Calculator
Find what percentage of units passed the first time.
Rework Rate Calculator
Find what percentage of units required rework.
Audit Sample Size Calculator
Find the sample size for zero-defects attribute sampling.
Quality Scorecard Calculator
Combine weighted quality dimensions into one score.
Time & productivity tools8 tools
Meeting Cost Calculator
Find what a meeting actually costs.
Deadline Calculator
Find your deadline date from a start date and lead time.
Work Hours Calculator
Find paid hours worked from clock-in and clock-out times.
PTO / Vacation Accrual Calculator
Project your leave balance from your accrual rate.
Focus Time / Pomodoro Budget Calculator
Find how many work/break cycles fit in your time.
Project Timeline Estimator
Find expected project duration from three estimates.
Billable Hours Calculator
Find your billable utilization rate and revenue.
Time Zone Meeting Planner
See a meeting time across multiple locations at once.
Data analysis tools4 tools
IQR & Outlier Boundary Calculator
Find Q1, Q3, IQR and outliers with Tukey's rule.
Percentile Rank Calculator
Find what percentile a value falls at.
Coefficient of Variation Calculator
Find relative variability as a percentage.
Missing Data Rate Calculator
Find what percentage of expected values are missing.
HR & people operations tools8 tools
Employee Turnover Rate Calculator
Find your staff turnover rate.
Headcount Planning Calculator
Project ending headcount from hires and separations.
Time to Fill Calculator
Find how many days it took to fill a requisition.
Employee Turnover Cost Calculator
Find the total cost of staff turnover.
Compa-Ratio Calculator
Find where a salary sits relative to the range midpoint.
Employee Net Promoter Score (eNPS) Calculator
Measure employee loyalty and advocacy.
Span of Control Calculator
Find the average direct reports per manager.
Diversity Ratio Calculator
Find what percentage of a group a category makes up.
Academic & research tools20 tools
Citation Generator
Create APA, MLA, Chicago, Harvard or IEEE citations.
Mean / Median / Mode Calculator
Find the mean, median and mode of any set of numbers.
Standard Deviation Calculator
Measure spread with population or sample standard deviation.
Confidence Interval Calculator
Estimate a confidence interval for a proportion.
P-Value Calculator
Compute a p-value for a z or t test.
Statistical Significance Calculator
Compare control vs variant in an A/B test.
Correlation Calculator
Measure the linear relationship between two variables.
Regression Calculator
Fit a simple linear regression line y = a + bx.
NPS Calculator
Calculate your Net Promoter Score from −100 to +100.
Reading Time Calculator
Estimate how long it takes to read any text.
T-Test Calculator
Run one-sample, independent or paired t-tests.
Chi-Square Test Calculator
Test goodness of fit or independence with χ².
ANOVA Calculator
Compare three or more group means with one-way ANOVA.
Effect Size Calculator
Measure effect size with Cohen's d.
Statistical Power Calculator
Estimate statistical power and required sample size.
Outlier / Grubbs' Test Calculator
Detect a single suspected outlier with Grubbs' test.
Z-Test Calculator
Run a z-test for a mean or a proportion.
Statistical Test Selector
Find which statistical test fits your design.
Cronbach's Alpha Calculator
Estimate the internal-consistency reliability of a scale.
Binomial Probability Calculator
Find the probability of a number of successes in fixed trials.
Explore professional guides
Professional and research guides: choosing a statistical test, sample size, workforce capacity, SLA compliance, process quality, ROI and more.