Which tool to choose
They're not equivalent for this task. Choose based on how you start.
Starting from a photo of the fridge or pantry? Go to Gemini, Google's AI assistant. The free version reads images from the camera and accepts requests via text, voice and photo. Handy because you open it from your phone and frame the shelves directly.
Starting from a written recipe or a link and just want to readjust it? ChatGPT in the free version is fine: you paste the recipe text and describe what to change. Keep in mind one limit: ChatGPT's free plan allows few images a day (currently two, JPEG, PNG, WebP and static GIF formats up to 20 MB each). If you have to photograph many different ingredients, it's not much.
Cook often and want to talk instead of write? Gemini free includes Gemini Live voice: you talk to it while your hands are busy and it replies by voice.
For most people reading this guide with their phone in the kitchen, free Gemini is the most practical choice: photo, voice and no tight cap on uploads.
How to do it
The logic is always the same: you say what you want to do, what you have and what you're missing, and let the AI recalculate. The point is to give context, not to ask generically "what do I cook?".
- Open the assistant (Gemini or ChatGPT). From browser or app the path doesn't change: there's a text field at the bottom and, next to it, the icon to attach a photo or open the camera.
- If you want to start from the real ingredients, tap the camera or paperclip icon and photograph the fridge, pantry or the ingredients on the table. Frame the labels well.
- Write or dictate the request using the syntax below.
- Read the proposal and check the substituted quantities before you get to the stove: it's the step most people skip.
- If something doesn't add up, reply in the same chat with the correction ("I only have 200 g of flour, not 300"): the AI recalculates while keeping the context.
The syntax when you start from a recipe to modify:
I need to make [name of the dish] for [number] people.
The original recipe calls for these ingredients: [list them].
I'm missing: [list what you don't have].
I have available in addition: [list any leftovers or ingredients to use].
Rewrite the recipe with the right substitutions, recalculate the quantities
for the number of people indicated and give me the step-by-step method.
Flag if a substitution changes taste or texture.
The syntax when you start from a photo of what you have at home:
In the photo are the ingredients I have at home.
Propose 3 dishes I can make using only these
(assume salt, oil, water and basic spices are a given).
For each, indicate prep time and difficulty,
then write the complete recipe of the quickest one.
Expected check: a recipe rewritten with quantities consistent with the number of people, the substitutions highlighted and an honest note on how the result changes. If the AI proposes you buy something you'd said you don't have, the request wasn't clear enough: repeat it adding "use exclusively what I listed".
A concrete example
Friday evening, you want to make carbonara for 3 people but you've opened the fridge and there's neither guanciale nor pecorino. You have diced smoked pancetta, grated parmesan, 4 eggs and the spaghetti.
You open Gemini, photograph the fridge shelf and write:
I want to make carbonara for 3 people.
I don't have guanciale or pecorino. In the photo you'll find what I have:
diced smoked pancetta, parmesan, 4 eggs, spaghetti.
Rewrite the recipe with these substitutions, give me the quantities
for 3 people and tell me how the flavor changes compared with the original.
The reply: pancetta in place of guanciale (browned without adding oil, because it already releases its own fat), parmesan in place of pecorino, 3 yolks plus 1 whole egg for the cream, and an honest note — the dish will be smokier and less savory than pecorino, so salt the water sparingly and set aside a ladle of cooking water to loosen the cream off the heat. In two minutes you have an executable recipe, not a lecture.
When it does NOT work (and how to fix it)
If the AI invents quantities that don't add up
It happens that it proposes disproportionate amounts or a wrong ratio (too much flour, little liquid). Don't trust it blindly: reply in the chat "Recheck the ratio between [ingredient A] and [ingredient B], it doesn't seem right to me". Forcing it to revise a single number works better than redoing everything. For leavened doughs, where the proportions are critical, verify the amount of yeast with a reliable pastry source before kneading.
If the substitution it proposes is impossible to find
Sometimes it suggests an "alternative" ingredient that you don't have either. Push back by narrowing the field: "Propose a substitution using only what I listed, no new ingredients". The AI tends to be generous with options: it's up to you to close the door.
If it doesn't recognize the ingredients in the photo well
Poor light or cut-off labels confuse the recognition. Fix: shoot in good light, get closer to the labels and, if it gets a product wrong, correct it in words in the chat ("That's not butter, it's margarine"). Also remember the free ChatGPT limit on images: if you have to show many ingredients, write them instead of photographing them, or switch to Gemini which is more generous.
If the recipe involves allergies or intolerances
Here the error isn't a dish that came out badly, it's a health risk. The AI can be wrong in identifying traces or hidden ingredients. Use it for the ideas, but verify every substitution against the product's real label and, in case of serious allergies, against your specialist. Safety isn't delegated to a generated suggestion.
A tip from someone who actually uses it
Don't close the chat after the first reply: keep it open like a sous-chef. While you cook and notice the cream is too liquid or that acidity is missing, write it there ("It came out bland, how do I fix it now that it's already in the pan?"). The AI knows the context of your recipe and gives you the correction on the fly, more useful than the perfect recipe written in advance. In the kitchen you correct on the go, and there the assistant truly earns its keep.
Frequently asked questions
Do I have to pay to use it for recipes?
No. Both ChatGPT and Gemini have free versions more than enough to adapt recipes. Gemini's free plan is tied to a Google account and isn't a timed trial: you use it without expiry. To write recipes you don't need the paid model.
Can I have it read the shopping list or the inside of the fridge from a photo?
Yes, it's one of the best uses. Free Gemini reads photos from the camera without tight caps. On ChatGPT it works, but watch out for the free limit of a few images a day: to photograph many different shelves, Gemini is better.
Are the quantities it gives me reliable?
For savory dishes done "by feel" (sauces, soups, pan-fried dishes) yes, with common sense. For pastry and leavened doughs, where a gram of yeast or a wrong ratio ruins everything, consider the amount a starting point and verify it. The AI reasons on typical proportions, but it doesn't have a scale: the final check stays with you.
Isn't it faster to search Google for a ready-made recipe?
For a standard recipe, often yes. But here the point is different: you don't have the standard ingredients. Searching "carbonara without guanciale with smoked pancetta for 3 people with parmesan" gives you back ten pages to filter; the AI readjusts your exact situation in one sentence and corrects you in real time while you cook. Search finds recipes; the assistant solves your fridge tonight.