Energy per Serving Calculator
Convert energy values between per 100g and per serve using serving size in grams.
Per 100g ↔ Per Serve Converter
Switch between "per 100g" and "per serve" to compare products and portions.
Energy per serve
—
General information only — not medical advice.
Presets
Per 100g → Per serve
Per serve → Per 100g
Usage & Reference
- Turning per 100g values into per-serve numbers you actually eat
- Comparing two products when serving sizes differ
- Understanding energy density when portion sizes vary
Many labels show energy both “per 100g” and “per serve”. The conversion is proportional scaling: per-serve kJ = (kJ per 100g ÷ 100) × serving size (g). Use the reverse tab to estimate kJ per 100g from a per-serve value.
Want to add items together? Try Meal Energy or explore the Food Energy Toolkit.
Questions about per 100g vs per serve
How do I convert kJ per 100g to per serve?
Multiply the kJ/100g value by (serving size in grams ÷ 100). This calculator applies the same proportional scaling used on food labels.
How do I convert per-serve kJ back to per 100g?
Divide the per-serve kJ by the serving size in grams, then multiply by 100. Use the second tab to do this instantly.
Why does serving size matter?
Per 100g is best for comparing products fairly. Per serve reflects what you actually eat. Converting helps you switch between both views.
Does this also convert to calories (kcal)?
Yes. Results show the kJ value plus the kcal equivalent for convenience.
Learn & Explore
Tip: Use the Toolkit to pick the right calculator for labels (per 100g vs per serve), meal totals, and daily reference values.