Source-backed comparison
Diet Coke vs Coca-Cola vs Coke Zero: UK Caffeine Guide
Compare caffeine in equal 330 ml UK servings of Coca-Cola Original Taste and Diet Coke using Coca-Cola Great Britain product information.
| Measure | Coca-Cola Original Taste | Diet Coke |
|---|---|---|
| Named serving | 330 ml can | 330 ml can |
| Market | UK | UK |
| Caffeine per serving | 34 mg | 46 mg |
| Caffeine per 100 ml | 10.3 mg | 13.9 mg |
| Value basis | Manufacturer listed | Manufacturer listed |
| Estimated after 5 hours | 17 mg | 23 mg |
| Absolute difference | 12 mg | 12 mg |
| Difference vs lower serving | 35.3% | 35.3% |
How to interpret the comparison
- Coca-Cola Great Britain lists 34 mg in a 330 ml Coca-Cola Original Taste and 46 mg in a 330 ml Diet Coke.
- Because the serving volumes are equal, the per-serving and per-100 ml comparisons point in the same direction: the named Diet Coke serving contains 12 mg more.
- The result applies to the named UK products and serving size; it should not be transferred to other cola brands, package sizes or markets.
Guide updated 2026-09-24
Diet Coke, Coca-Cola and Coke Zero: read the full product name
The short answer
For the documented UK 330 ml cans, Diet Coke has 46 mg and Coca-Cola Original Taste has 34 mg. Standard Coca-Cola Zero Sugar contains caffeine; Zero Sugar Zero Caffeine is a separate product.
Inspect the documented servings
These values come from the linked catalogue records. A source-backed record is not a measurement of your drink or a guarantee of a current recipe.
| Drink / market | Serving | Caffeine | Per 100 ml | Evidence / action |
|---|---|---|---|---|
| Diet CokeUK | 330 ml can | 46 mg | 13.9 mg (calculated) | Manufacturer listedVerified source record · Reviewed 2026-08-21Use this dose · Compare |
| Coca-Cola Original TasteUK | 330 ml can | 34 mg | 10.3 mg (calculated) | Manufacturer listedVerified source record · Reviewed 2026-08-21Use this dose · Compare |
| Coca-Cola Zero Sugar Zero CaffeineUK | 330 ml can | 0 mg | 0 mg (calculated) | Manufacturer listedVerified source record · Reviewed 2026-09-04Use this dose · Compare |
Bars use the selected measure; numbers remain visible in both units. No bar is drawn for an undocumented concentration. Per 100 ml = serving caffeine × 100 ÷ documented volume.
What we can compare numerically
Diet Coke and Original Taste are equal-volume named servings, so their 12 mg difference is not a can-size effect. Standard Coke Zero is not assigned a numerical amount here: the reviewed GB product page establishes caffeine as an ingredient but does not give the dose. Unknown is not zero.
Scale a portion, not a recipe
The drink pages let you adjust quantity and volume from each documented concentration. Scaled results are estimates for the same formulation. They should not be transferred to other countries, flavoured versions or the caffeine-free variant.
Sources and scope
- Coca-Cola Great Britain caffeine FAQGreat Britain FAQ and serving size. Source reviewed 2026-08-21.
- Coca-Cola Great Britain product announcementOfficial Great Britain announcement for the zero-caffeine variant, including the 330 ml can format. Source reviewed 2026-09-04.
- Coca-Cola GB: Zero Sugar productsReviewed 24 September 2026: standard Zero Sugar lists caffeine flavouring. Do not confuse it with the Zero Caffeine variant.
Educational information, not medical advice. Published, calculated and approximate values have different limits. Check the current product label or recipe when an exact amount matters.
Calculated five-hour timeline
This table applies the same exponential half-life equation to both starting amounts. It does not show measured blood levels or predict which drink will affect a particular person more.
| Hours after serving | Coca-Cola Original Taste | Diet Coke |
|---|---|---|
| 0 | 34 mg | 46 mg |
| 3 | 22.4 mg | 30.3 mg |
| 5 | 17 mg | 23 mg |
| 8 | 11.2 mg | 15.2 mg |
| 10 | 8.5 mg | 11.5 mg |
| 12 | 6.4 mg | 8.7 mg |
Sources
- Coca-Cola Great Britain caffeine FAQGreat Britain FAQ and serving size.
- Coca-Cola Great Britain caffeine FAQGreat Britain FAQ and serving size.
Find lower-caffeine alternatives to Coca-Cola Original Taste or compare drinks against a bedtime target.