What actually shipped
Until now, every result — BMR, TDEE, your daily calorie deficit, macro breakdowns — was shown exclusively in kcal, which matches US food labeling but leaves out anyone whose everyday nutrition labels are printed in kJ first. The new toggle closes that gap directly inside the tool, rather than asking you to keep a separate cheat sheet open in another tab.
It's a display-layer feature: the toggle rewrites the unit and number shown on the card, using the standard conversion of 1 kcal ≈ 4.184 kJ. Nothing about how BMR, TDEE, or your deficit is calculated has changed — only how the resulting numbers are presented to you.
Where to find it and how it behaves
Here's the flow: pick a tab — say, BMR/TDEE — fill in your profile, hit Calculate. On the results card that appears, a compact segmented control shows two options, kcal and kJ, with kcal selected by default (matching the calculator's original behavior). Tap kJ, and every "<number> kcal" string already on that card — including labels like "kcal/day" — updates in place to show the kilojoule equivalent.
Switching is instant and reversible. There's no recalculation step, no page reload, and no need to touch your profile inputs — the toggle simply re-renders the numbers that are already on screen. Tap back to kcal at any time to compare both readings side by side (mentally, since only one unit shows at a time).
The toggle works independently of the existing imperial/metric switch in the profile section. That control changes how you enter height and weight (lb/ft-in versus kg/cm); the new kJ/kcal switch only changes how energy results are displayed, regardless of which measurement system you've chosen for your body stats.
A worked example of the switch in action
Here's a hypothetical example to illustrate what changes on screen — not a specific real result, just numbers to show the pattern. Suppose the BMR/TDEE tab returns a TDEE of 2,400 kcal/day. Before the toggle, the card reads "2,400 kcal/day." Tap the kJ button, and that same line becomes roughly "10,042 kJ/day" — the calculation behind the number hasn't moved at all, only its label and displayed value.
| Result field | kcal view | kJ view (toggle on) |
|---|---|---|
| TDEE | 2,400 kcal/day | ~10,042 kJ/day |
| Daily deficit target | 500 kcal/day | ~2,092 kJ/day |
| Daily calorie goal | 1,900 kcal | ~7,950 kJ |
| Protein macro calories | 560 kcal | ~2,343 kJ |
The same applies across the Macros tab's donut and breakdown rows: any "kcal" value present is converted the same way, so your whole macro plan can be read consistently in kilojoules if that's the label format you're used to shopping with.
Why this update, and what it doesn't change
The motivation is straightforward: nutrition labeling isn't universal. Shoppers in much of the EU, Australia, and New Zealand are used to seeing kJ as the primary energy figure on packaging, while US labels lead with Calories. A calculator that only spoke kcal was asking those users to do a manual conversion every single time they wanted to compare a result to what's on the label in front of them. The toggle removes that friction.
What it deliberately does not do is touch any of the underlying formulas. BMR is still calculated with Mifflin-St Jeor (or Katch-McArdle if you've entered a body-fat percentage), TDEE still applies your activity multiplier, and the deficit-to-timeline math still assumes 3,500 kcal ≈ 1 lb of fat. The toggle is purely cosmetic in the best sense of the word — it changes how the same trustworthy numbers are presented, not what they mean.
See the new kJ/kcal switch for yourself — calculate your BMR, TDEE, or macros and flip the toggle on the results card.
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