What is ROI in Betting and Why It's the Only Stat That Matters

Betting Stats | 10 Novembre 2025

In the world of sports betting, everyone talks about "wins". People brag about the €1000 bet slip they hit with €2, the @15.00 odds they guessed at the last minute. But almost no one talks about how much money they spent to get that win.

If you win €1000 but you spent €1200 on lost bet slips to get there, you are not a winner. You are at a €200 loss.

This is where the most important (and most ignored) statistic for bettors comes in: the ROI.

What is ROI (Return on Investment)?

ROI, or "Return on Investment", is a percentage that tells you how much you are gaining (or losing) in relation to how much you have invested (wagered).

The formula is simple:

ROI = (Net Profit / Total Wagered) * 100

• Net Profit: The sum of all your winnings MINUS the sum of all your stakes.
• Total Wagered (or Turnover): The total sum of all the amounts you have staked (real stake only, not bonuses).

Practical Example:

Imagine two bettors, Anna and Bruno.

• Anna wagers €100 total (10 bets of €10). At the end of the month, she has won €130. Her Net Profit is €30 (€130 won - €100 wagered).
  Anna's ROI: (€30 / €100) * 100 = +30%
• Bruno wagers €1000 total (100 bets of €10). At the end of the month, he has won €1050. His Net Profit is €50.
  Bruno's ROI: (€50 / €1000) * 100 = +5%

Bruno earned more in absolute terms (€50 > €30), but Anna was a much more efficient bettor. She generated a 30% return on her capital. Bruno had to risk €1000 to get just a 5% return.

Why is ROI More Important Than a Single Win?

1. It separates luck from skill

Anyone can get lucky and win a bet. But maintaining a positive ROI over the long term (over 100, 500, 1000 bets) proves that you have a valid strategy, that you know how to find "value odds", and that you manage your money well.

2. It tells you the truth

ROI is brutal but honest. It doesn't care about your "feeling" or the fact that you "were close". A negative ROI means that, overall, you are losing money. Period. Seeing that number forces you to re-evaluate your strategy.

3. It is fundamental for Bankroll Management

Knowing you have a stable ROI of 5% allows you to calculate how much you can afford to bet (bankroll management) to grow sustainably. If you don't know your ROI, you're just guessing.

How to Start Tracking Your ROI?

It's impossible to calculate ROI if you don't track every single bet you make. Not just the winning ones. You must record:

1. Date of the bet
2. Amount staked (Stake)
3. Total odds
4. Potential winnings
5. Outcome (Won, Lost, Refunded)

Doing it on an Excel sheet is a good start, but it quickly becomes complicated. You have to constantly update formulas, be careful not to delete data, and manually calculate cumulative profit.