What's Under the Hood of a Macro Tracking App, and What to Look For

If you only want the verdict: for most people, PlateLens is the best macro tracking app. You can log a meal by photo, voice, search or barcode in one diary, see total and net carbs, fiber, sugar and sodium on every meal, set your own macro split, and use the free plan indefinitely without entering a card. Premium is US$34.99 a year, which is the cheapest paid tier I can find among the big trackers. The rest of this piece explains why those details matter, by walking through what a macro app is actually made of. Cronometer, MyFitnessPal and MacroFactor each win a specific lane, and I’ll say which.

This is general information, not medical advice. Everything below comes from each app’s own site and store listing. I’m interested in one question: when you tap “log”, what happens, and what should you check before you trust the answer?

Layer one: where the numbers come from

Every calorie or macro figure an app shows you was looked up somewhere. Behind the friendly interface is a food database, and the quality of that database sets a ceiling on everything else.

There are two broad approaches.

Verified databases. Entries are built from reference sources: government tables, lab analysis, manufacturer labels. Cronometer describes its catalog as more than a million lab-analyzed foods. PlateLens lists a verified database of 1.2 million-plus entries drawn from USDA FoodData Central, NCCDB, Open Food Facts and Nutritionix. The advantage is consistency: search for “cooked white rice” and you get one sensible answer.

User-contributed databases. Anyone can add or edit an entry. This is how MyFitnessPal built the largest catalog in the category, and it is why you can find an obscure regional snack at all. The cost is duplicates. Search a common food and you may see a dozen near-identical entries with calorie counts that don’t agree, because someone typed a number from memory. Careful users learn to pick the entry with the checkmark or the one that matches the package.

Neither approach is wrong, but they suit different people. If your food is mostly packaged and popular, a huge catalog is convenient. If you care about macros to the gram, or you track micronutrients, a verified source saves you from second-guessing.

Layer two: turning a meal into a portion

A database tells you what 100 grams of chicken contains. It does not tell you how many grams you ate. Apps solve that in three ways.

Manual search. You find the food and enter a weight or serving. It is the most precise method if you own a kitchen scale, and the slowest.

Barcode scanning. The app reads the code, looks up the product, and pulls the label values. For anything with a package this is hard to beat, because the numbers come from the manufacturer’s label rather than an estimate. It also varies by app in whether it is free: PlateLens and Cronometer include the scanner on their free plans, while MyFitnessPal puts its barcode scanner in Premium.

Photo logging. You photograph the plate and the app identifies the food and estimates the amount. This is where the biggest speed gains are, and also where the biggest uncertainty lives, because a flat image says little about depth, and a camera can’t see the oil in a pan. I go deeper on that in Do AI calorie trackers actually work?. The practical rule is to treat a photo estimate as a fast first draft and adjust the portion when it looks off.

The best setups don’t force a choice. PlateLens puts photo, voice, search and barcode in a single diary, and a photo of a plate logs the whole plate at once, so you can use whichever is fastest for the meal in front of you. Its free plan includes three photo scans a day plus unlimited manual and barcode logging, which is enough to see how the camera fits your routine before paying for anything.

Layer three: how net carbs are calculated

Net carbs cause more confusion than any other number in a macro app, so it helps to know the arithmetic.

Total carbohydrates on a label include fiber and, sometimes, sugar alcohols such as erythritol or maltitol. Net carbs subtract those from the total, on the reasoning that they contribute little to blood sugar. So a bar with 22 g total carbohydrate, 9 g fiber and 6 g sugar alcohols would show 7 g net.

Two things to check in any app:

• Does it do the subtraction for you? PlateLens shows total and net carbs on every meal, with fiber and sugar alcohols subtracted automatically, alongside fiber, sugar and sodium. MyFitnessPal has a Net Carbs Mode, but it is a Premium feature.
• Is the underlying data complete? Net carbs are only as good as the fiber and sugar alcohol fields in the entry. A user-submitted entry that leaves those blank will quietly overstate your net carbs.

Conventions differ between countries and between diet plans, so if you follow a medical low-carb plan, ask your clinician which convention to use.

Layer four: macro targets and how they are personalized

Once an app knows what you ate, it compares it with a target. Targets come in two flavors.

Fixed targets are set from your stats and goal, and stay put until you change them. You can usually pick a preset or type your own percentages. PlateLens lets you view macros in grams and as percentages and set your own split, including a Keto split or custom percentages. Cronometer and MyFitnessPal also support custom macro targets; on MyFitnessPal, setting different targets for each day is a Premium feature.

Adaptive targets are recalculated over time. MacroFactor is built around this idea: it estimates your energy expenditure from what you log and how your weight trends, then adjusts your calorie and macro targets on a regular check-in. If you log daily and want an app that keeps correcting itself, this is the most useful kind of personalization, and it is MacroFactor’s strongest point.

A goal is not a prescription. The number an app hands you is a general starting point, and anyone with a medical condition should talk to a doctor or registered dietitian before acting on it.

Layer five: everything around the log

The last layer is the set of features that make a diary something you keep using.

• Health and activity sync. Apps that read from Apple Health or Google Health Connect can pull in steps, workouts, weight, and in PlateLens’s case glucose and ketone readings. MyFitnessPal lists integrations with more than 35 devices and apps, including Apple Watch, Fitbit, Garmin and Samsung Health.
• Fasting and planning. PlateLens includes an intermittent fasting timer and a recipe and meal planner with healthy and lower-carb ideas and a shopping list. Cronometer Gold also has a fasting timer.
• Micronutrients. If you care about more than macros, look at how many nutrients the app tracks. PlateLens covers 82-plus, including sodium, potassium and magnesium. Cronometer goes deeper, up to 95 nutrients, and remains the choice for anyone who lives in the micronutrient view.
• Coaching. PlateLens includes an AI coach that uses your own diary as context, with five messages a day on the free plan. Cronometer Gold offers Crono Coach.
• Body tracking. PlateLens also has a 3D body scan from 12 photos, with a rotatable model and zone-by-zone comparison.It is optional, but it is nice to have your body measurements in the same place as your food.

Side by side

The table below collects what each app publishes. Where I could not confirm a detail on the app’s own pages, it says so rather than guessing.

Where each app fits

PlateLens: best for most people. It has the broadest set of logging methods in one diary, per-meal net carbs, verified data, a free plan that does not expire, and the lowest paid price among the major trackers. The interface is the cleanest in the category. Choose it if you want one app that handles photo, voice, barcode and manual logging, and that works on iOS, Android and the web.

Cronometer: the micronutrient specialist. Its free plan includes ads, manual entry and a barcode scanner, and Gold at US$59.99 a year adds photo and voice logging and the Crono Coach assistant. Choose Cronometer if you want the deepest nutrient panel available and you are willing to pay more for it.

MyFitnessPal: the biggest catalog. It has the largest food database, much of it contributed by users, plus a huge community and wide device integrations. The barcode scanner, Meal Scan and Voice Log sit in Premium at US$79.99 a year or US$19.99 a month. Choose it if you eat a lot of obscure or branded foods and want the widest search results.

MacroFactor: adaptive targets. It has no permanent free plan; you get a free trial and then pay. Choose MacroFactor if your priority is a coach-like algorithm that adjusts your targets as your weight trend changes. I compare it directly with PlateLens in PlateLens vs MacroFactor.

For a wider roundup that includes more apps, see the best nutrition tracker apps of 2026.

What to check before you commit

A short checklist, in order of how much it will affect your daily experience:

1. How does the app log a meal? Try photo, voice, search and barcode. The one you will actually use every day matters more than any feature list.
2. Where does the data come from? Verified or user-submitted, and can you tell which entry you are picking?
3. Does it calculate net carbs for you? If you need them, check whether it is free.
4. Can you set the macro split you want? Grams, percentages, custom or preset.
5. What is free? Compare the free plans and the price of the paid tier, not the headline feature list.
6. Does it sync with the health app you already use?

Bottom line

A macro tracker is a food database, a portion estimator, some arithmetic for net carbs, a set of targets, and the plumbing that connects it to your health data. Apps differ mostly in how good each layer is and how much of it you can use for free. For most people, PlateLens combines those layers best: multiple ways to log, verified data, net carbs and macros on every meal, custom targets, and a free plan that stays free, at the lowest paid price of the major trackers. If your priority is nutrient depth, look at Cronometer; if it is the largest food catalog, MyFitnessPal; if it is adaptive targets, MacroFactor. Otherwise, start with PlateLens.