What are betting units, and why do people use them incorrectly?

Some years ago, the concept of units was restricted to stats nerds, like the people behind this site. Today, it is widely used, which is great - but still, people frequently ask what units are, and there are just so many tipsters using them incorrectly. So let's talk about it.

What are units?

Units are a fictional currency used in betting accountancy and for comparing results. You still place your bets in pounds, dollars, euro, etc. - but when you log your bets or breg about your winnings, you should convert to units.

Uhm... why?

The basic problem is that you betting £20 says absolutely nothing. How much is that for a punter with a bankroll of £200 000? How much is that for somebody with a bankroll of £200? And most importantly: what does it say about your own bankroll?

That £20 bet means you either practically tell people how much money you have available for betting - or you don't tell them anything of value at all. Neither is particularly desirable. It also makes it very difficult for knowledgable punters betting small stakes to share their bets, while bad players with far too much money for their own good gain way too much attention.

By using units, the size of your - or anybody's - bankroll is irrelevant. You define what a unit means, and then you use that consequently, which makes it easy to compare your results to those of others.

So how much is a unit, then?

This is indeed the heart of the matter, and it is closely related to the question of how much you should risk on a bet. ​ The gist of it is that you can decide for yourself how much a unit is - but it should always be a very low percentage of your total bankroll. Common unit sizes range between 0.5 and 2 per cent.

Hence why people started using units to begin with: when you share a bet with others, and they see that you bet 1 unit, they can assume that this corresponds to something like 1 % of your bankroll, give or take. If they want to make the same bet, they can simply use 1 unit of their own - regardless of what that means in actual currency.

Why are people betting then betting 10 units per bet?

It didn't take long for a problem with units to emerge: if you only stake 1 u per bet (this is called "flat"), there's no way of changing your bet sizing in accordance with your bet evaluation. Hence, if you have a really, really good bet, it is likely mathematically favourable to put a bit more money at stake than you usually would. So what do you do then? Well, perhaps you bet 2 units instead of 1.

In other words: if how you evaluate a bet affects how much you put at risk, you need to adjust your units.

However, there are two major issues with this:

1. People on Twitter call for "MAX BET!!!!" all of the freaking time. This is an expression which you'll see only very rarely from serious punters, and only when absolutely called for. Someone who keeps finding max bets non-stop should be carefully scrutinised.

2. Unless the range is fixed, the units system doesn't work as a tool for comparison.

What does fixing the range mean?

Even by using (for instance) 1-10 units per bet, you need to somehow determine how much of this would be equivalent to 1 unit in a flat betting system. Otherwise, someone backing your bet has no way of knowing how you estimate its value. Betting 8/10 units without also saying what it actually means is no different in principle from saying "the bet is great!" without offering any extra info.

A very common way of solving this conundrum is to let 5/10 u in a relative system correspond to 1 u flat. Logically, this makes 10/10 u correspond to 2 u flat. But fixing your range can be done differently as well. Using 1-10 without defining what this means mathematically is incredibly common, but also a red flag since you have no way of telling whether the range is mathematically justifiable or not.

It's also exceedingly common on - again - Twitter to do 1-10 units in theory only to use 7-9 for all bets regardless. In practice, this is the same thing as fixing the range to make 8/10 u correspond to 1 u flat. People doing this should, if they were reasonable, simply delete the first six numbers from their range entirely, if they aren't going to place such bets anyway.

What does this mean when comparing results?

There is a huge problem with relative unit ranges: namely, that you can no longer comparing results by counting the number of units won.

Let's say one person bets using a 1-5 u range, and another person bets using a 1-10 u one. Both players make a 200 u profit over a three-month period - who do you think did best? Even accounting for the impossibility of telling for sure without fixing the ranges, it seems quite likely that the player using significantly smaller stakes will, on average, have done better. ​ Instead, ROI - return on investment - has overtaken the units as a measurement tool. It's a much better tool anyway, so we consider that a net win for everyone. An ROI of 8.4 %, for instance, simply means a return of 108.4 units on 100 units staked, for a profit of 8.4 units.

To be fair, this is an entire discussion in itself as well, but it's important to realise that ROI means average profits per bet. Given an ROI of +5 %, a thousand bets, and £100 per bet - you'd make a profit of 1000 * (£100 * 1.05 - 100) = £5000. Or, but more simply, it means you make £5 per bet in average profit, times a thousand to account for all placed bets.

So, basically, you guys think that everyone is fraudulent?

Well, no, that's not quite it - but there are multiple layers to sports betting, all of which being important to understand for a player looking to establish success over extended periods of time.

1. You need to be able to evaluate events.

2. You need to be able to convert your evaluation into numerics - i.e. percentages, and hence into odds.

3. You need to be able to manage your bankroll.

There's no shortage of people being great at one or two things but not at all three. But do note that nothing of the above is relevant to our discussion on units!

So let's make it abundantly clear that using a units system is mostly only about facilitating communication with others and being able to compare their results. It may also help you in your bookkeeping. (You do keep book, right? If not, head to our sheets section straight away and create a sheet at once - it's in your own best interest.) It shouldn't affect your gambling in any other way than you deciding on how much to put at stake on a bet - but it does have huge importance for people looking to back you based on your past results. And, of course, this by extension applies to you when backing others.

In this day and age, considering how ridiculously easy it is to share bets all over the world, it's more important than ever that you understand the concept behind units - yet people in general are worse at it than ever. So do be careful, and ask if you're unsure.