Printable T* Pocket Card

Quick answer: the critical t values you need most are in four columns: 90%, 95%, 98% and 99% confidence (two-tailed α = 0.10, 0.05, 0.02, 0.01). For 95% confidence, t* = 2.228 at df = 10, 2.086 at df = 20, 2.042 at df = 30, and 1.960 in the ∞ row. This page builds a one-card t-table you can print, cut out and keep in a notebook or calculator case.

Pick the columns and rows you need, highlight your df, and print. Pocket size fits two cards on one landscape sheet; full page gives large print for a desk or wall.

Build your t* pocket card

Columns (confidence level · two-tailed α; up to 5):

Rows:

Print size:

Type your degrees of freedom to highlight its row, then print.

Critical t values (t*) · ttable.org

df90%95%98%99%
2-tail .12-tail .052-tail .022-tail .01
1-tail .051-tail .0251-tail .011-tail .005
16.31412.70631.82163.657
22.9204.3036.9659.925
32.3533.1824.5415.841
42.1322.7763.7474.604
52.0152.5713.3654.032
61.9432.4473.1433.707
71.8952.3652.9983.499
81.8602.3062.8963.355
91.8332.2622.8213.250
101.8122.2282.7643.169
111.7962.2012.7183.106
121.7822.1792.6813.055
131.7712.1602.6503.012
141.7612.1452.6242.977
151.7532.1312.6022.947
161.7462.1202.5832.921
171.7402.1102.5672.898
181.7342.1012.5522.878
191.7292.0932.5392.861
201.7252.0862.5282.845
211.7212.0802.5182.831
221.7172.0742.5082.819
231.7142.0692.5002.807
241.7112.0642.4922.797
251.7082.0602.4852.787
261.7062.0562.4792.779
271.7032.0522.4732.771
281.7012.0482.4672.763
291.6992.0452.4622.756
301.6972.0422.4572.750
401.6842.0212.4232.704
501.6762.0092.4032.678
601.6712.0002.3902.660
801.6641.9902.3742.639
1001.6601.9842.3642.626
1201.6581.9802.3582.617
∞ (z)1.6451.9602.3262.576

Two-tailed α = 1 − confidence; one-tailed α = half of it. df = n − 1 (one sample), pairs − 1 (paired), n₁ + n₂ − 2 (pooled). Not on the card? Use the next smaller df.

Values are Student’s t quantiles rounded to 3 decimals and match the t-table on our homepage wherever both list the same df (the homepage also has df 1000).

Worked example

Question: you have n = 16 measurements. What t* do you need for a 95% confidence interval, and for a one-tailed test at α = 0.05?

Step 1. df = n − 1 = 15. Find row 15 on the card.

Step 2. 95% interval: two-tailed α = 0.05, the 95% column: t* = 2.131.

Step 3. One-tailed α = 0.05: use the column whose second header says 1-tail .05 (the 90% column): t* = 1.753.

Check: both match the full t-table, row 15. Not sure about df? Practise with DF Race.

FAQ

What is the critical t value for a 95% confidence interval?

Use the 95% column (two-tailed α = 0.05) at df = n − 1. For example df = 10 gives t* = 2.228, df = 20 gives 2.086, df = 30 gives 2.042, and as df grows it approaches z* = 1.960 (the ∞ row).

How do I read one-tailed values from the card?

Each column has two headers. A one-tailed α is half the two-tailed α, so one-tailed 0.05 sits in the same column as two-tailed 0.10 (90%). For df = 15 that is t* = 1.753.

What if my df is not on the card?

Use the next smaller df that is printed: its t* is slightly larger, so the result is conservative. For df = 45 the card’s df = 40 row gives 2.021 (two-tailed 0.05), while the exact value is 2.014. For an exact t* at any df, use the t-table calculator.

How do I print the pocket card?

Choose your columns and rows, pick “Pocket (2 per sheet)” or “Full page”, then tap Print card. The print layout hides the site menu and ads. Pocket size prints two copies side by side on a landscape sheet with a dashed cut line; choose “Save as PDF” in the print dialog for a PDF.

What does the ∞ row mean?

It is the limit of Student’s t as df grows without bound, which is the standard normal z critical value: 1.645 (90%), 1.960 (95%), 2.326 (98%) and 2.576 (99%). For z-scores and normal areas see z-table.com.

Related t-table pages