Putting the minds of many to rest, research has come up with the magic number.
It turns out size does matter - but to the relief of many average men, bigger might not be better.
A survey asked 4,761 women to recall the size of the bloke's todger from their last sexual encounter, and they were asked if they could climax via penetration.
Big One Dating, who carried out the research, then compared orgasm success rate with penis size to find out what worked for women on average.
Their findings suggest the best size for women to climax is eight inches - but any bigger and the orgasm rates drop.
In fact, men with a whopping 11-inch member got 30 per cent of women to reach climax, the same proportion for men with a four inch penis.
Although a three inch John Thomas is considered a "micro penis", a quarter of women asked said they had been satisfied in their last sexual encounter.
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The average penis size in the UK is between 3.5-5.8 inches.
But in a big win for ability over size, one in 10 men with a one inch penis still hit the spot.
And a large proportion of women in the survey also said girth was important to being able to orgasm.
In general, as penis length increases so does width, so the average girth of the eight inch penis is likely to be a contributing factor.
So if you are looking to try increase your manhood, or at least the appearance of it, there are a few options out there...
1. Lose the flab
Professor Kevan Wylie, a sexual medicine consultant, told the NHS: "Many men who worry about the size of their penis generally have overall body image issues.
"What happens is that they tend to focus their poor body image on their penis."
Being overweight can leave men with low self-esteem and overall poor body image.
But a beer belly hanging over your penis can also make your penis look smaller, so if you want to impress then try and cut down on the pints.
2. Keep trim
A big mound of pubic hair can make your penis look smaller than it is, so dig out the shaver- ideally not the same one you use for your face.
By keeping your hair down there in good shape, you can make sure all focus is on your member.
It will also go a long way to making it look a decent size.
3. Get in shape
It goes without saying that if you're feeling attractive your sex life will also benefit.
So not only will getting fit make you look better, you're bound to feel good about yourself.
It's also a cost-free way to boost your confidence - you don't need a fancy gym, just dig out your trainers and get jogging.
4. Penis pumps
Penis pumps involve placing a tube over the penis and then pumping out the air to create a vacuum.
This draws blood into the penis and makes it swell.
Penis pumps are sometimes used as a short term fix for erectile dysfunction, because they make the penis hard.
But prolonged use can damage the tissues in the penis, making your erections weaker, so it's not hugely recommended.
And Prof Wylie said there is very little evidence to suggest pumps give you extra length in the long run.
Penile extenders involve placing a weight or small extending frame on the flaccid penis to stretch it.
Yes, you are essentially stretching the flesh of your manhood.
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But it has to be done for several hours every day for six months to have any impact.
And if you use extenders the wrong way you could damage the flesh of your penis, which can be disastrous for your sex life.
"There's some evidence that traction devices can have some impact, particularly with men who are smaller in size," Prof Wylie said.
"Some patients using traction devices for six months have noticed a gain in size of 1-2cm.
"However, such treatments shouldn't be started without the supervision of a doctor."
Somewhat similar to extenders, jelqing is when you repeatedly pull a flaccid penis using your thumb and index finger to increase length.
The idea behind it is that it increases the blood capacity of the penis and therefore makes it bigger.
But there's little evidence to suggest it actually works - and you could end up causing injury for no gain.
Docs can increase the girth of your penis with fillers - a non-surgical option.
One way is to inject fat from other parts of your body into your member, but studies have found that it can cause long-term disfigurement if the fat doesn't distribute properly.
Another way is to inject hyaluronic acid - the same stuff that is used for lip fillers. This is non-permanent.
If you are really committed to going to extreme lengths to literally increase your length, surgery is an option.
Surgeons can cut the ligament that attaches your penis to the pubic bone and perform a skin graft to give you extra length.
It might give you an extra 2cm, but it may also make your erection point lower than before.
"A lot of men who have this treatment don't truly appreciate this loss of angle," says Prof Wylie added.
"It can make sex quite uncomfortable. You've got to do a lot more manoeuvring with your partner.
"The advantage of a 2cm gain in flaccid length is far outweighed by the loss of angle of erection."
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There are also other options including to remove excess skin around the scrotum that can go as far up as the middle of the shaft, giving the appearance of more length.
9. Pills and lotions
There are a number of pills and lotions you can buy that contain hormones, that claim to make the penis larger.
But there is very little evidence to suggest these work and may even contain dangerous substances.
Dr Sarah Brewer, Medical Director of Healthspan, told The Sun: "Numerous products are sold online that claim to enlarge the size of the penis.
"There is no evidence that taking any herbal supplements or applying any creams will have an enlarging effect."
Professor Wylie doesn't recommend them, but added: "Using a lotion may help a man become more familiar with his penis, which some men shy away from.
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"So lotions can help a man become more comfortable with his penis but they certainly won't make it any bigger."