Cocksure

Guides

Straight, evidence-based answers to the questions people are too embarrassed to ask.

Guide

What Determines Penis Size? Genetics and Hormones

Penis size is set mostly by genetics and prenatal hormones, and locked in by the end of puberty. Here's what the evidence supports and what changes nothing.

July 1, 2026
Practical

Large & XL Condoms: How to Know If You Actually Need One

Most men buy XL by ego, not fit. Learn why condom size is about girth, not length, how to find your nominal width, and what "large" really means in millimeters.

June 17, 2026
Myths

Do Penis Pumps Actually Work? The Honest Answer

Penis pumps work for erections, not permanent size. Here's what the box delivers, what the marketing implies, and the two things that actually change how big you look.

June 17, 2026
Myths

Does Masturbation Affect Penis Size? The Honest Answer

Masturbation does not shrink, stretch, or stunt your penis, and here's the biology that explains why the old myths fall apart.

June 17, 2026
Health

Does Penis Size Change With Age? The Honest Answer

Your erect size is basically set after puberty and stays stable for decades, though it can dip modestly in older age and look smaller from weight gain.

June 17, 2026
Myths

Does Jelqing Work? The Honest, Evidence-Based Answer

There's no good evidence jelqing permanently increases size, and the milking technique carries real risks like bruising and nerve damage.

June 17, 2026
Measuring

How to Measure Your Penis Without a Ruler (Accurately)

Lost your ruler? Mark your length on a paper strip or string, then scale it against a credit card or dollar bill for a real number.

June 17, 2026
Research

Average Penis Size 2025: What the Latest Research Actually Says

The newest data still points to one gold-standard study of 15,521 men, and here's why that stability is a good sign, not a stale one.

June 17, 2026
Culture

What Reddit Gets Right (and Wrong) About Penis Size

Reddit nails the average and the percentile instinct, then trips over inflated self-reports, porn baselines, and locker-room myths — here's the line between them.

June 17, 2026
Guide

Average Penis Size by Age: The Adult Chart, 20s to 60s+

Average penis size barely changes after puberty, and most 'size by age' charts are fabricated. Here's what clinician-measured data actually shows.

June 9, 2026
Comparison

calcSD vs BigDickGuide vs Cocksure: Which Penis Size Calculator to Trust

calcSD, BigDickGuide, or Cocksure? Which penis size calculator actually uses clinician-measured data — and which to trust with your number.

June 4, 2026
Data

How Accurate Are Penis Size Studies?

Why do average penis size studies disagree? Measurement method, bone-pressed technique, and self-reporting bias explain most of the gap.

June 2, 2026
Guide

Girth vs Length: Which Actually Matters More?

Length vs girth: which matters more? What clinician-measured data (Veale 2015) and the Prause preference study actually say about both.

May 27, 2026
Practical

How to Find the Right Condom Size (by Girth)

Condoms fit by girth, not length. Measure your circumference, convert it to nominal width, and buy by the number instead of the label.

May 19, 2026
Comparison

Penis Size Compared to Everyday Objects: An Honest Reality Check

What does 5.16 inches actually look like? We turn the average — and your size — into everyday objects you've held, from a soda can to a banana.

May 14, 2026
Reassurance

Is 5 Inches Normal? What the Data Actually Says

Is 5 inches normal? Yes — it lands right around average on clinician-measured data. Here's exactly where it sits on the curve and what that means.

May 11, 2026
Myths

Is Penis Size Linked to Height, Shoe Size, or Race?

Does height, shoe size, or race predict penis size? The correlations are tiny to nonexistent. A clear-eyed look at why the myths persist.

May 5, 2026
Reassurance

Is There an Ideal Penis Size? What the Data Actually Says

Is there an ideal penis size? Short answer: no. But there's real data on what most people prefer and why the extremes matter less than you'd think.

April 27, 2026
Guide

Flaccid vs. Erect: Why the Soft Number Tells You Almost Nothing

Flaccid vs erect: the average soft penis is 9.16 cm (3.6 in), the average erection 13.12 cm (5.16 in) — and one barely predicts the other.

April 21, 2026
Data

Mean vs. Median Penis Size: What the Numbers Actually Tell You

A clear, calm breakdown of average and median erect penis size, percentiles, the bell curve, measurement methods, and what partners actually report wanting.

April 11, 2026
Myths

Can You Actually Increase Penis Size? What Works and What's a Scam

Can you actually make it bigger? Pills, pumps, and jelqing mostly don't work. Here's what the evidence supports and what's just a scam.

March 31, 2026
Guide

Will My Penis Still Grow? An Adult Size Reality Check

Wondering if your penis will still grow? If you're an adult, the answer is no — growth finishes in late puberty. Here's the honest reality check.

March 29, 2026
Measurement

How Do Urologists Measure Penis Size? The Clinical Method

Measure at home three nights running and you'll get three numbers. Urologists use one standardized method — here's exactly how they do it.

March 13, 2026
Reassurance

Does Size Matter? What the Research Actually Says

The science of penis size and why it matters less than you think. What the data shows, what partners actually prefer, and where size genuinely counts.

March 8, 2026
Measurement

Measuring a Curved Penis: The Right Method and When a Curve Needs a Doctor

A curve makes a straight ruler lie about your length. Here's how to measure a curved penis accurately — and when a bend means seeing a doctor.

February 24, 2026
Medical

What Counts as a Micropenis? The Clinical Threshold

A micropenis is clinically defined as an erect length under 9.3 cm (3.66 in) — about 2.5 standard deviations below average. What the threshold means.

February 17, 2026
Measurement

BPEL vs NBPEL: The Measurement Gap Explained

Two men, identical penises, measurements an inch apart — the difference is bone-pressed vs not. What BPEL and NBPEL mean and how to convert.

February 3, 2026