Free calculators
Survey and statistics calculators
39 calculators to plan a survey, score the answers and test the results. Every calculation is checked against reference values, and nothing you type leaves your browser.
- Checked formulasEvery calculator is tested against reference values: statistical tables for the tests, worked examples for the rest.
- Sources on the pageWhere a method or a threshold comes from a paper or a book, the page names it.
- Free, no sign-upUse any calculator as often as you like. Your numbers stay in your browser.
- Three languagesEvery calculator works in English, Spanish and Portuguese.
What do you need to work out?
Pick your task and go straight to the right calculator.
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NPS, CSAT, CES, eNPS and SUS from your survey answers.
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Likert scales, star ratings, top-box shares, weighted scores and moving a score to another scale.
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Sample size, margin of error, confidence interval, invitations and response rate.
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Quotas, fieldwork pace, survey length, survey and panel cost, ROI and A/B splits.
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Completion and drop-off rates, and how many answers survive cleaning.
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Significance tests, correlations, reliability, effect size and descriptive statistics.
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All calculators
39 calculators in six groups.
Customer and employee metrics
- NPS calculatorNet Promoter Score from 0–10 ratings: % promoters − % detractors
- CSAT calculatorCustomer Satisfaction Score: the share of 4s and 5s on a 1–5 scale
- CES calculatorCustomer Effort Score: mean ease rating on a 1–5 or 1–7 scale
- eNPS calculatorEmployee Net Promoter Score from 0–10 ratings, with promoter and detractor shares
- SUS calculatorSystem Usability Scale score from 0 to 100 from the ten statements
Scales and scores
- Likert scaleMean score, top-2 box and negative share for 1–5 answers.
- Average ratingWeighted average of 1–5 star reviews with high and low shares.
- Top-box calculatorTop-1, top-2 or top-3 box share for 1–5 and 0–10 rating scales
- Weighted scoreFinal score across criteria with different weights.
- Score normalizationConvert a score between scales, such as 1–5 to 0–100.
How many people to survey
- Sample size calculatorHow many responses you need: Cochran formula with finite population correction
- Margin of error calculatorThe ± range around a survey percentage, with finite population correction
- Confidence interval calculatorRange around a survey percentage at 90%, 95% or 99% confidence
- Two-group sample sizeRespondents per group to compare two proportions or means (power, MDE)
- Survey invitations calculatorHow many people to invite for the number of responses you need
- Response rate calculatorResponse rate from invites and completes, or invites needed for a target
- Incidence rate (IR)Share of screened people who qualify for the survey.
Fieldwork and budget
- Quota plannerSplit a sample by gender, age or region into counts per group
- Quota progressProgress, current pace and pace needed by the deadline.
- Fieldwork timeDays needed to collect your sample at your daily pace.
- Survey lengthMinutes to complete, from question types and timings.
- Survey costTotal research budget and cost per valid response.
- Panel costPanel budget from CPI, incidence rate and buffer.
- Survey ROI calculatorOne-year return from churn reduction, conversion lift or avoided losses
- A/B sample splitterSplit a sample between 2–4 test variants, evenly or by weights
Data quality
Statistical analysis
- A/B test significanceIs the conversion difference significant? Two-proportion z-test
- P-value calculatorP-value from a z-score for a two-tailed or one-tailed test
- Chi-square calculatorAssociation of two categorical variables: χ², p-value and Cramér's V
- T-test for two groupsWelch's t, degrees of freedom and p-value for two groups.
- Pearson correlation calculatorLinear relationship of two variables: r, r² and p-value from paired X and Y
- Spearman correlationSpearman's rho for ranked or ordinal X,Y pairs.
- Cronbach's alpha calculatorScale reliability from item scores: α and alpha if item deleted
- Effect sizeCohen's d and Hedges' g for two group means.
- Standard deviation (SD)Sample and population SD, mean, range and CV.
- Coefficient of variationCV = SD ÷ mean × 100%, from a list of numbers or a mean and SD
- Median and percentile calculatorMedian, quartiles, IQR and any percentile from a list of numbers
From a number to real answers
A calculator tells you what to collect. SurveyNinja collects it.
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Calculate
Work out the sample size, the metric or the test you need.
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Build the survey
Start from a ready template or describe the survey to the AI, then add logic and quotas.
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Share it
Put the link in your email or chat, print a QR code or show the survey on your site.
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Read the results
See charts in the report and export the answers to Excel, CSV or SPSS on every plan.
Questions about the calculators
Are the calculators free?
Yes. Every calculator is free and works without sign-up. The maths runs in your browser: the numbers you enter are not sent to us.
Which calculator do I need?
To plan a survey, start with the sample size calculator, then invitations and response rate. To score answers, use NPS, CSAT, CES or eNPS. To compare groups, use A/B significance, chi-square or the t-test. To check a questionnaire scale, use Cronbach's alpha.
Which formulas do they use?
Standard published methods: Cochran's formula for sample size, the Wilson interval for proportions, z, t and chi-square tests, Pearson and Spearman correlations. Each page shows its formula, a worked example and, where a threshold is quoted, its source.
Can I use the results in a thesis or a report?
Yes. We test the calculations against reference values, from statistical tables for the tests. In your report, name the method and the parameters you used (confidence level, margin of error, test), as you would with any software.
How are the calculators different from SurveyNinja surveys?
A calculator works with numbers you already have. In SurveyNinja you collect the answers themselves: the report of an NPS question calculates NPS for you, and responses export to CSV, Excel or SPSS for further analysis.
Can I share or save a result?
Yes. Copy the result as text, copy a link that opens the calculator with your numbers, or print the result.
Can I paste data from Excel or Google Sheets?
Yes, where a calculator takes a list of values: paste a column, one value per line. In Spanish and Portuguese the decimal separator is a comma.
What is the difference between NPS and CSAT?
NPS measures loyalty: one 0–10 question about recommending you. CSAT measures satisfaction with a specific contact or purchase, usually on a 1–5 scale. Use NPS for the overall relationship and CSAT right after a touchpoint.
Ready to collect real answers?
Build a survey in SurveyNinja, share it today and read the results in one report. Start on the free plan.