David Ogilvy said:

Nobody, at any level, should be allowed to have anything to do with advertising until he has read this book seven times. It changed the course of my life

So how does this affect online conversions? Hopkins was a proponent of quantifiable results and the measurement of response rates. He even pioneered split testing in his mail order ads by testing different variations with ‘response codes’ on the coupons.

This meant that he could identify which ad generated which leads. Working in newspaper advertising, Hopkins was paying for the space used by his ads, so every word, image and whitespace had to deliver value. 

Mail order advert showing response code:

Despite being 90 years since the book was published, the principles and lessons are still valuable today and many are used by leading brands to drive conversion:

1. Make it personal

Hopkins observed that receiving a free gift is not a big motivation. They are too common so are often just ignored. Instead he suggests sending a letter encouraging the person to claim a free book with their name embossed on the front

The amazing result was that almost every person who received this message responded to him giving information about themselves:

When a man knows that something belongs to them – something with his name on – he will make an effort to get it

Apple has taken this literally, making the opportunity to customise your product the first step of the checkout process. By showing a preview of the customisation on the product you are buying, you can see your purchase with your name on it, and feel  ownership of the product.

This simple technique makes you more likely to complete the checkout, as your personalised device is waiting for you:


LinkedIn uses this same principle to encourage people to move jobs. By showing a ‘profile’ for you in a new role they build a connection in your mind with that job. You can see yourself in the role and are more likely to make the effort to apply:

Facebook also do this very well. By including your profile picture and an empty text box in a stream of comments they give the impression that you are already part of the conversation. It is then a small step from that to actually make a contribution: 

2. Limit the offer

The key conversion challenge is to change a user from a prospect to a sale. Hopkins addressed the common problem of people being distracted or comparing with other manufacturers by limiting his offers. Adding a limit (such as an expiry date), compels the user to act now, with little consideration, as they are afraid they will lose out.

Daily deal sites take advantage of this principle by giving time limited offers and showing the offer ‘selling out’ so there is a strong drive to purchase.

Panic sets in and users instinctively buy before having the chance to compare prices elsewhere (or to consider whether they actually need the item).

Hopkins went further, however, suggesting that by showing people the cost of delay, they can be encouraged to act sooner. 

Energy Comparison sites warn of upcoming price rises and encourage their users to switch now to lock in current rates:

These sites haven’t yet gone as far as showing the cost of not switching, but this could help to convince people to make the change. For example, the wireframe below shows how a comparison site could show this cost to the user:

3. Images

In mail order advertising, space costs money, so each picture must earn its place. Hopkins describes a man selling incubators who added a picture which made his advert more striking. It cost an extra 50% to include, but when the results were analysed, the expensive image didn’t bring a single additional sale.

The Mead Cycle company obsessively tested images and copy, to the point where, even for $10,000, Mr Mead wouldn’t change a single word in his ads.

Like Mead, Autoglass test hundreds of images on their homepages worldwide, making sure each one pays its way and that the most appealing version of the site is shown to each viewer:

(Uplift gained from different images on the Autoglass worldwide sites).

Although delivering an image on a site has negligible cost, it can make a huge difference to the conversion of the page. A particular image may look striking, however it shouldn’t be chosen solely on looks and each image must earn its place.

Image testing is simple and can be implemented by any testing tool. As a low effort technique it can bring high rewards and should be included as part of a testing programme, particularly in ‘downtime’ between more complex tests.

4. Specific claims

Anyone can claim to be ‘the cheapest’ or that their product is quick to use. It’s very easy to make general claims like “Best in the World” or “Lowest prices in America”.

Hopkins gave the example of a man who overcame this by stating “Our net profit is 3%”. It was definite and impressive and his prospects couldn’t believe that anyone could undercut him at this rate. The business grew quickly.

Although advertising your profit margin may not be feasible, sites such as gocompare and MoneySupermarket make very specific claims:

Confused.com shows precise savings and numbers of comparisons for Car and Home insurance.

By specifying the exact value of savings and the number of providers compared, users can believe the figures and they give the site credibility.

Hopkins also mentions a safety razor manufacturer who, instead of advertising a “quick” shave, advertised a 78-second shave. This was definite, and clearly backed up by tests and data. People believed this and his sales rose greatly.

By timing people while they complete your form and then publishing the exact time on the site, you will increase credibility. Moneysupermarket advertises that a quote will take “five minutes”. This is stronger message than “Get a quote in minutes” as it implies a measured and accurate time. Users will believe this and be confident to proceed.

MoneySupermarket advertises that a car insurance comparison takes just five minutes.

5. Headlines

Headlines are often neglected by optimisers, but can bring some of the greatest returns. In a newspaper, the article or advert headline is the only opportunity to gain readers’ attention. The purpose is to pick out the people who may be interested.

A clever, but irrelevant headline may attract many more people; however they may not actually be interested in your product.

People have little time. Even in the 1920s, Hopkins noted that people skipped 75% of the reading matter that they paid to receive. Because of this, he spent hours on each headline and emphasises that the headline must focus on the benefit that the user receives.

Hopkins’ example is of selling soap:

  • “Keep Clean” might attract a small audience as it is nothing special.
  • “No animal fat” may only appeal to a small proportion of people
  • “It floats” may be interesting but doesn’t bring potential buyers
  • A good headline will focus on “beauty” and “complexion” – people want these things

Visual Website Optimizer dedicates a large part of their homepage to the headline and focuses on the benefits to the user. It is a simple, striking headline and conveys the concept simply:

E.ON have also crafted careful headlines, which both capture the reader’s interest and keep the messaging relevant:

This headline was hugely successful. The campaign increased trust and resulted in 300,000 customers signing up for an energy monitor and over 100,000 users taking surveys on their site.

Headline tests are simple to implement and can generate massive increases in conversion. By focusing on the user and the benefits your product gives them, you will capture the attention of your target market and convince them to stay on your site.

6. Guarantees

Many people are sceptical of the value of guarantees. As most sites must offer refunds by law, consumers no longer see this is a differentiator.

Hopkins addressed this issue too. When advertising specific products he observed many more people purchased if the guarantee was offered by the local dealer rather than the manufacturer.  Instead of a far-away stranger, someone nearby was responsible for any returns. 

Retailers such as Schuh allow returns to be processed in store. This tangible return path gives the user confidence.

For online-only retailers, making the process clear and free gives users more trust. ASOS offer a variety of returns policies, giving customers the confidence to experiment with clothing purchases:

By going a step further than other retailers, you can recapture the power of the guarantee. For example Lovehoney offer a 365 day, no-quibble returns policy (even if the items have been used!) By going a step beyond the usual, they have a clear differentiator and build customer confidence and loyalty.

Hopkins notes that the most powerful form of guarantee is offering the product on approval. You can try it free for 30 days, and only pay if you want to keep it. Although familiar to Readers Digest subscribers, this has yet to be experimented with in e-commerce.

It is, however, a huge driver of Software sales. Services such as Spotify and Visual Website Optimizer offer 30 day free trials, where there is no cost to the user from trying the product.

This can be reinforced by not asking for a credit card. The user is taking no risk, so there is little barrier to conversion.

A guarantee or generous returns policy shows you have confidence in your product and service, and gives customers the confidence to buy from you without risk.

Two men came to me, each offering me a horse. Both made equal claims. One man said, “Try the horse for a week. If my claims are not true, come back for your money.” The other man also said, “Try the horse for a week.” But he added, “Come and pay me then.” I naturally bought the second man’s horse.

7. Invite comparison

The challenge for many sites is to get their product or service noticed in an increasingly packed market. Even if your product is best, getting it noticed is hard. 

Hopkins warns people to avoid ‘selfish appeals’ when comparing to rivals. It is appealing to warn people not to use a sub-standard alternative but buyers resented this approach.

Instead, by stating “Try our rivals too”, it shows absolute confidence in the product and no fear of competition. Sonos have been running a fantastic ad campaign capitalising on this:

There is no question in the buyer’s mind – to be able to invite comparison in this way, the product must be superior. Google is seen as an impartial comparison and users may not even need to do the search (although it does only return positive reviews).


Over the past 90 years, Hopkins’ principles have been tested again and again, bringing great benefits to those who use them. Even in a rapidly changing world, they remain relevant and the sites which apply them can significantly increase conversion.

It is important to remember Hopkins’ most important lesson – to make every image, word and feature on your site earn its place and to quantifiably test everything you do.

Never do anything because some uninformed advertiser considers that something right. Never be led in new paths by the blind. Apply to your advertising ordinary common sense. Take the opinion of nobody, whom know nothing about his returns.