Customers at Costa Coffee have to fork out £71.55 to get a free drink under the firm's loyalty scheme.
The worst offender was Costa coffee where customers have to fork out £71.55 to get a free cup.
Costa's reward scheme, the Costa Coffee Club, offers five points for every £1 spent in their store. That means that someone purchasing a large latte, which costs £2.65, will accumulate 10 points.
To get £1, you need 100 points, or 1p per point - meaning each latte is only worth 10 pence under the loyalty scheme. Customers would then need to by 27 cups in order to get the 265 points needed for a free coffee.
Starbucks also runs a reward scheme
Starbucks My Rewards works by awarding a point for each purchase - regardless of the final bill amount. - with a free drink once you've got 15 points.
This means customers need to spent £40.50 in order to get a larger latte - the equivalent of 15 cups.
Researchers for Channel 4 show Supershoppers, found McDonald's loyalty scheme to best value as customers only need to purchase six cups in order to get a freebie - the equivalent of £11.34.
Retail expert Clare Bailey, from Retailchampion.co.uk, said: "You do have to spend a lot of money at Costa to get your freebie so don't stick to just one loyalty scheme.
People have to spend more than £70 to get a free coffee in Costa
"If you drink at Costa regularly it is worth being a member of the reward system as you get free Wi-Fi and other perks. Collect loyalty points at all the places you shop and eat and when a freebie comes up it is a nice perk - rather than going out of you way to be a loyal customer."
- Supershoppers, is on Channel 4 at 8pm on Tuesday.
How many coffees do you need to buy to get a freebie?
- Cafe Nero, buy 9 get 10th free, 9, £25.20, £2.89
- Starbucks, buy 15 get 16th free, 15, £40.50, £2.70
- McDonald's, buy six get seventh free, 6, £11.34, £1.89