Paste the list you already have
Problem: homework and lab sheets arrive as commas, spaces, or new lines. Capability: the app cleans the values so you can calculate immediately. Outcome: you spend the time on sample vs population, not on retyping.
Standard Deviation Calculator
Standard Deviation Calculator — sample and population spread, with every step shown.
Paste a dataset and get sample (s) or population (σ) standard deviation in seconds. Mean, deviations, variance, and the square root stay visible — not hidden behind a single answer.
- Sample (n − 1) and population (N)
- Every calculation step on screen
- Datasets stay on this device
- Lifetime Pro is one-time, not a subscription
Benefits
Built for the mix-up that actually happens
People rarely struggle to tap a button. They struggle to pick the right formula, trust the number, and show the working. This standard deviation calculator is built around that.
Choose sample or population
Problem: s and σ look alike until the divisor is wrong. Capability: switch n − 1 and N with a tap and see which formula matches the question. Outcome: the same dataset can answer both “these five scores” and “a draw from a larger class.”
See the working, not only σ
Problem: a headline number is hard to check. Capability: Show solution walks mean, deviations, squares, variance, then the square root. Outcome: you can copy the same path you would write on paper.
Read the graph
Problem: spread is abstract until you see it. Capability: a bell curve with 68 / 95 / 99.7 bands, dataset bars, and a box plot. Outcome: you can tap a value and see how many standard deviations it sits from the mean.
Keep history on the phone
Problem: yesterday’s list is gone when you close a web tab. Capability: recent calculations save locally, up to 50 entries. Outcome: reopen a dataset without an account or cloud sync.
Lessons next to the calculator
Problem: formulas live in a textbook, the numbers live in another app. Capability: in-app guides cover what standard deviation is, Bessel’s correction, and the 68–95–99.7 rule. Outcome: you can check the idea, then paste the list on Home.
How it works
Four steps from a raw list to a checked result
The flow matches a textbook calculation. The app does the arithmetic and keeps the table.
Enter or paste
Type numbers, paste from notes, or load an example such as 10, 34, 23, 54, 9.
Pick the formula
Sample if the list is a subset. Population if the list is the whole group you care about.
Calculate
Get standard deviation, mean, variance, and related stats. Open Show solution for the working table.
Read, save, share
Use the graph, reopen history, copy the result, or export an image. PDF export is included with Lifetime Pro.
Screenshots
The calculator, the working, and the graph
These are real screens from the Android app with Lifetime Pro unlocked, so ads are not in the frames.
Use cases
Use Standard Deviation Calculator for
Homework with a shown solution
Walk the six steps on the same numbers you were given, then compare the working table to what you wrote. See how to calculate standard deviation.
Exam scores and class spread
Two classes can share a mean and still differ in spread. Paste both lists and read s next to the mean. See how to read the number.
Lab readings
Repeat measurements often want population or sample SD plus range and IQR. Keep the list local; nothing is uploaded.
Choosing s versus σ
If the question is about a larger group, divide by n − 1. If the list is the whole group, divide by N. See sample vs population standard deviation.
Guides
Learn the method, then use the app
Each page answers one search. The calculator is there after the method, not instead of it.
What is standard deviation?
How far values sit from the mean, in the same units as the data.
Read the guideHow to calculate standard deviation
Six steps and the worked set 10, 34, 23, 54, 9.
Read the guideSample vs population
When to use s (n − 1) and when to use σ (N).
Read the guideThe two formulas
Bessel’s correction, variance, and the computational shortcut.
Read the guideThe 68–95–99.7 rule
What the empirical rule says — and when a tiny dataset will not follow it.
Read the guideHow to read the number
CV, outliers, and why SD is large or small only next to the mean.
Read the guideStandard deviation calculator for Android
What to look for in an Android SD calculator, then how this app maps to that list.
Read the guideFAQ
Questions people actually type
How do I calculate standard deviation on Android?
Enter or paste the list, choose Sample or Population, tap Calculate, then open Show solution if you need the table. The steps are the same as on paper: mean, deviations, squares, divide, square root.
When should I use sample vs population standard deviation?
Use sample (s, n − 1) when the values are a draw from a larger group you care about. Use population (σ, N) when the list is the entire group. The app can show both on the same numbers.
What is the easiest way to see the working?
After you calculate, tap Show solution. You get the formula with your numbers, then a table of each x, x − mean, and (x − mean)².
Can I calculate without an account or cloud sync?
Yes. Datasets and history stay on the device. There is no sign-in. The calculator can compute with no network. Ads, analytics, crash reports, and purchases use the internet when those features run.
What app can I use for sample and population standard deviation?
Standard Deviation Calculator is an Android app from TQ Tech that switches s and σ, shows the working, and graphs the list. Core calculation is free; Lifetime Pro is a one-time unlock for no ads, extra precision, and PDF export.
Is Lifetime Pro a subscription?
No. It is a one-time Google Play purchase. It does not auto-renew. Restore is free if you already bought it on the same Play account.
Does the 68–95–99.7 rule always apply?
Only as a sketch for roughly bell-shaped data. Skewed or tiny lists will not follow it closely — which is why the app also plots your actual values.
Ready to measure spread with the working shown?
Download Standard Deviation Calculator and paste a dataset on Android.