What's cheaper, buying chickpeas in cans or rehydrating and cooking them yourself?
Intuitively I'd have guessed the home cooked chickpeas would be cheaper, but I wasn't sure. Maybe if you cook them in large enough batches you can somehow offset the increased costs of cooking and shipping water?
So I did the math myself.
The price of chickpeas varies quite a bit depending on which ones you buy. I sampled a few offers from Coop, Migros and Lidl. For cooked chickpeas the cheapest price I found was 2.76 CHF/kg (non-organic, sold in 540g jars) and the most expensive one was 10.83 CHF/kg (organic, sold in 120g cans).
Dried chickpeas on the other hand are priced similarly everywhere - probably due to the fact that they all come in a standard 500g bag size and are organic. Prices range from around 4 CHF to around 6 CHF.
All in all you pay a premium for not shopping at a discounter, for buying organic and for buying smaller batches - no news here. I could imagine you could get cheaper chickpeas by shopping at a Turkish supermarket, but that's probably true for both canned and dried chickpeas.
For the sake of comparison, let's just take the cheapest cooked vs the cheapest dried chickpeas. The dried chickpeas are organic and the cooked ones aren't, but whatever. At this point it looks like the cooked chickpeas win handily (2.76 CHF/kg vs 3.98 CHF/kg). But dried chickpeas gain weight while soaking and cooking. How much exactly?
After soaking their weight had increased to 407g - more than 2x!
Cooking added another 10g to that. I had to try a chickpea or two to taste for done-ness, so that's not included in the weight after cooking.
All in all, that's roughly a 110% increase in weight. For a fair comparison, this takes the dried chickpeas from 3.98 CHF/kg raw down to 1.91 CHF/kg, clearly cheaper than the canned chickpeas.
But wait, cooking them did use some gas and water. How does that factor in?
I don't actually pay for water myself, the water costs in this building are distributed evenly across the tenants. Also water is really cheap around here, about 1 CHF/m³, so I'll consider it negligible. As for the gas costs: I took a photo of the gas counter before
and after cooking.
As you can see, I've used up around 0.032 m³ of gas. Interestingly cooking gas is paid in kWh, at a rate of 0.15 CHF/kWh. Looking at my old bills I found a conversion rate of 10.906 kWh/m³, which means cooking the chickpeas cost about... 0.05 CHF.
You could cook more than 200g at once and have the costs go down, but I'm just going to scale that up to an entire kg of cooked chickpeas and assume around 0.13 CHF for 1kg of final product.
All in all, the grand total is 2.04 CHF/kg for dried compared to 2.76 CHF/kg for cooked.
So yes, dried chickpeas are quite a bit cheaper than canned ones, even if you get the organic ones. Realistically however, chances are that your labor cost dwarfs everything else, especially if you write a blog post about it. Cooking is mostly unattended time, but it's still non-zero work. There is of course also the cost of cleaning the dishes but you can re-use the pot you used to cook the chickpeas to cook the actual meal. Personally, I very much prefer the taste of freshly cooked chickpeas too.