Close this search box.
Subtotal: $0.00

No products in the cart.

Subtotal: $0.00

No products in the cart.

What Is The Best Percentage For Split Testing Emails?

Split testing, also known as A/B Testing, is a powerful way to really understand what works for your audience and get better results and ROI from your digital marketing campaigns. 

It works off the methodology of sending different types of messaging to different people and seeing which performs better. So you choose a portion of your segment to include in the testing, and then send the better performing version to everyone else.

Split testing gets you better results from individual campaigns, and also helps you build up data that ensures better effectiveness long term.

As with nearly everything you do there’s ways to get better results and effectiveness from your split or A/B testing. This includes but is not limited to deciding which segments of your audience to include in the tests, how many people in those segments you should use, what to test and how long to run the test for.

We unpack some of those intricacies below. 

Split Testing: An Overview

By now, you should be aware that segmentation matters. Very few of your sends are suitable to be sent to your entire database every time. The easiest way to describe segments is to use a car dealer example – the messaging you’d send to people who had test driven a car is very different to what you’d say to people who had bought one.

Split testing helps you take that segmentation even further to really get to know the behaviours of people within that demographic. You can test things like subject lines, content, call to action, scheduling, layouts, use of images and other design features and more. You shouldn’t test them all at the same time though. You need to be able to clearly see what worked and that gets blurred if you’re doing too much at once. Even if you see definite results, you won’t be sure what created them. 

Most contemporary software applications like ActiveCampaign and Klaviyo make it really easy to conduct split testing. There are inbuilt features that virtually automate parts of the process and the details you take care of are easy. You just need to decide who to include in the test, and what you’re testing. 

So What Percentage of Your Database Makes A Good Test? 

Spoiler alert: it’s not as simple as just doing a 50/50 split. It’s also not too complicated either.

It’s not that you can’t literally split your segment or list down the middle, it’s that there’s more effective ways to do it, especially if one of your tests performs dramatically better than the rest.

That’s why the best split tests are for a significant but smaller portion of your database first – then you can still use the better version for the bulk of your database to maximise returns.

We recommend using 30% of your database in your testing. So you send 30% of recipients your two versions, and then the remaining 70% receive the better performing one once the test is complete.  These figures can be adjusted, but we don’t recommend going more than 10% either way. 20% is the minimum amount of recipients needed for an effective Split Test, and 40% is the maximum you should aim for.

We work with 30% as a general rule because it’s a big enough sample size to be able to trust the results and see discernable differences in audience behaviour, while allowing a lot of room to reap the rewards if your test winner has the potential to bring big boosts in revenue or engagement to your campaign results.

Initially, you don’t need to be too concerned about how engaged your audience is to be included in your test. You never know – it could be that change you’re testing that re-engages someone who rarely opens your emails and that’s valuable data too. Though this is also a great time to think about your overall CRM hygiene and whether it’s time for a tidy up.

How Long Should A Test Run For?  

This is one of those “how long is a piece of string?” style questions because it does depend on a few factors, and this is where your own data can come in handy.

Have a look at your previous campaign activity and explore when people interact with your content. Also consider what you want people to do – and when – once they’ve interacted with your send. 

Unless you’re specifically testing a shorter time frame – and this can be beneficial at times. For example, to help you understand how to time your promotional activity for a flash sale. We wouldn’t advise jumping into the deep end with that kind of test for your first one though, or at least not without engaging assistance to make sure it’s done effectively.

Generally if you’re starting out with split testing, you want to give your test at least five to seven days to run.

To truly understand your database’s behaviour, you want to be able to see which days and times are most effective. You might learn that your database is most active on a Thursday, but that intel is lost if you only run the test for 12 hours on a Monday. 

Don’t forget that the very point of testing is to get real data that you can use to make informed decisions for future campaign work. So if you want to get started with split testing straight away, here’s an exercise you can implement (or modify to suit your database):

  1. Choose a less time sensitive send – a message that still has relevance and value to recipients whether they get it immediately or in a week. For example, your monthly newsletter is just as meaningful if your audience gets it in the last week of the month prior as it is if they get it in the first week of the month it’s intended for. Letting people know that your new season stock has arrived is also less time sensitive than a restock that’s likely to sell out within days (or hours as some items do!).

    2. Start small. Remember even if there’s multiple things you want to test, you don’t want to do it at once. A great way to get a feel for how split testing works and improve results include things like using two different subject lines (bonus points if you can add personalisation like a name to one of them).

    3. Let your system do the heavy lifting for you. Many of the contemporary platforms like Klaviyo, ActiveCampaign and more have inbuilt split testing features that virtually automate the process for you.

    4. Don’t forget to go back and analyse the results once the test and send has been completed.  

Let’s Talk Split Testing Strategy  

Do you want to have a chat about your current digital marketing campaigns and how Split Testing could make them even more effective? (Read: make you even more money). Book a complimentary strategy call with the Greenfish Marketing Team today. Reserve your time here. 

Related Posts

Have You Got The Right Automations To Make More Money This Black Friday Period?

With Black Friday just around the corner, it’s time to

Is SMS Part of Your Black Friday Strategy?

Hey, e-commerce warriors! It’s that time of year again –

Is Your Email Marketing Ready for the Black Friday Frenzy?

Hey there, ready to dive headfirst into the Black Friday

Privacy Policy

Confidentiality of Information

All personal information is treated as strictly confidential to Greenfish Marketing. It will never be sold or bartered or otherwise transferred to a 3rd party, without your express permission.

This section details what information Greenfish Marketing collects, why it is collected and how that information may be used.


Collection of Information

In order to utilise some aspects of this website, Greenfish Marketing may require you to provide a certain amount of information. This includes information required to create an ID (such as your name and email address) and preference information (likes/dislikes). We use this information to provide you with a service or a better online experience.

In order to better understand how our customers use this site, we collect and analyse some aggregate information about our site users. This includes such things as what time of day they visit the site, what browser they use and what pages they visit.

Greenfish Marketing logs all activity and maintains audit trails of usage of this site. We use this information in the detection and prevention of fraud and other malicious activities.

Greenfish Marketing will not send a “spam” or unsolicited email or SMS, nor will Greenfish Marketing provide your details to a third party, unless you have given us permission.


Accessing your personal information

If you want to access any personal information we have about you, email us at When making a request, you should specify the type/s of information you want to access. If your request for access is refused, we will give you a written reason for this. We will try and process your request as quickly as possible but may charge you a fee for doing so.


Changing your personal information

If the personal information we hold about you is wrong or needs to be changed, please email us at and we will take reasonable steps to ensure your personal information is corrected.


Email and SMS

When you register your interest, download a free report or complete an online query in any way on this website we will retain this information in order to respond to your query and communicate with you. You can update this information at anytime or opt out of receiving any further marketing communications. If you become a customer of Greenfish Marketing we will need to continue to contact you for development, progress or performance related matters.

If you access the Greenfish Marketing Pty Ltd web site you agree to be bound by the conditions contained in this legal message and further agree that the Courts of Australia shall have exclusive jurisdiction in respect of any dispute arising from this legal message.


Web Browser Cookies

Our website may use “cookies” to enhance user experience. User’s web browser places cookies on their hard drive for record-keeping purposes and sometimes to track information about them. User may choose to set their web browser to refuse cookies, or to alert you when cookies are being sent. If they do so, note that some parts of the site may not function properly.


Earnings Disclaimer

Results may vary from individual to individual in calculating profits, and depend on the industry, capacity, advertising budget and other factors. The sales figures stated above are our own personal sales figures. Please understand our results are not typical, we’re not implying you’ll duplicate them (or do anything for that matter). The average person who follows any ‘how to’ information gets little to no results. We’re using these references for example purposes only. Your results may vary and depend on many factors including but not limited to your background, experience, and work ethic – we make no guarantees whatsoever. All business entails risk as well as massive and consistent effort and action. If you’re not willing to accept that, then we’re not a great fit for you.

When Greenfish Marketing informs you about or makes reference to business opportunities or money-making opportunities, you understand and agree we have made no promise, representation, implication, warranty, suggestion, projection or guarantee whatsoever that you will make a certain amount of money, or any money, or not lose money, as a result of pursuing such opportunities or using our products and services, and that we do not authorize any such promise, representation, implication, warranty, suggestion, projection or guarantee by others.



Greenfish Marketing Pty Ltd assumes no responsibility for the contents of any other web sites to which the Greenfish Marketing Pty Ltd web site has links.

To the extent permitted by law Greenfish Marketing Pty Ltd shall not be liable to any person for any loss or damage which may arise from the use of any of the information contained in this web site. The material contained in this web site is a guide only.



The copyright in the material contained in the Greenfish Marketing Pty Ltd web site belongs to Greenfish Marketing Pty Ltd. Except solely for your own personal and non-commercial use no part of this web site may be copied, performed in public, broadcast or adapted without the prior written permission of Greenfish Marketing Pty Ltd.



To complain about a breach of the Australian Privacy Principles, you can contact us by emailing or write to us at 132 Cremorne Street, Cremorne, Victoria 3121. We will review your complaint and respond to you promptly in writing.


Contacting Us

If you have any questions about this Privacy Policy, the practices of this site, or your dealings with this site, please contact us at:

Greenfish Marketing Pty Ltd
132 Cremorne Street, Cremorne VIC 3121
03 9973 1788
0426 272 644


The Ultimate Email Sending Checklist

  • This field is for validation purposes and should be left unchanged.