Quick Reference
| Characteristic | Light | Medium | Dark |
|---|---|---|---|
| Internal temp | 356–401°F | 410–428°F | 437–482°F |
| Color | Light brown | Medium brown | Dark brown / oily |
| Acidity | High | Medium | Low |
| Body | Light | Medium | Full |
| Bitterness | Low | Medium | High |
| Origin flavor | Pronounced | Balanced | Subdued |
| Roast flavor | Minimal | Balanced | Dominant |
| Caffeine (weight) | Slightly higher | Middle | Slightly lower |
What Roasting Actually Does to Coffee
A green coffee bean is grassy, dense, and undrinkable. Roasting triggers a cascade of chemical reactions — the Maillard reaction and caramelization — that develop the hundreds of aromatic compounds that make coffee taste like coffee.
As the bean heats up, it loses moisture and CO₂, expands, and undergoes two key moments called "first crack" and "second crack." Where a roaster stops the process determines the roast level.
- First crack (~390–400°F): The bean pops like popcorn as steam escapes. This is where light roasts end — origin character is preserved, acids are intact, body is lighter.
- Between cracks (~410–428°F): Medium roast territory. The roast starts adding its own flavor — chocolate, caramel, nuts — while still retaining some origin character.
- Second crack (~437°F+): Oils migrate to the surface. Roast-forward flavors dominate — smoky, bitter, dark chocolate. Origin character is largely gone.
Light Roast Coffee
Light roast stops at or just after first crack. It retains the most origin character — the terroir, varietal, and processing method come through clearly. You'll taste things like floral notes, fruit, bright citrus acidity, and tea-like delicacy.
Light roasts are higher in acidity and lower in body than darker roasts. They tend to reward careful brewing — grind finer, use hotter water (200°F+), and brew slowly to extract the complexity.
Best for: Pour over, Chemex, AeroPress, drip. Coffee lovers who enjoy terroir and complexity. Single origin beans shine here.
Medium Roast Coffee
Medium roast is the most forgiving and most popular roast level in the US. It balances origin character with roast-developed sweetness — think milk chocolate, caramel, almond, and dried fruit — without tipping into smoke or bitterness.
The surface of medium roast beans is dry (no oil migration yet). Body is fuller than light, acidity is mellower. Medium roast works with virtually every brewing method and is the sweet spot for most everyday drinkers.
Best for: Drip coffee, pour over, French press, espresso. The most versatile roast level — the safest choice if you're not sure.
Dark Roast Coffee
Dark roast extends past second crack, where the bean's oils migrate to the surface (giving beans that shiny look). The extended heat breaks down acids and many of the complex aromatic compounds from the origin, replacing them with roast-developed flavors: dark chocolate, smoke, roasted nuts, and bittersweet caramel.
Dark roasts have the lowest acidity and highest bitterness. They hold up well in milk-based drinks — espresso, lattes, cappuccinos — where the bold flavor cuts through dairy without disappearing.
Best for: Espresso drinks, cold brew, French press, mochas. If you drink coffee with cream and sugar, or want a bold, heavy cup.
The Caffeine Myth
This is the single most common misconception about roast level: dark roast does not have more caffeine.
Caffeine is extremely heat-stable — it doesn't burn off significantly during roasting. However, the longer roasting process does cause the bean to lose mass and expand in size. This means:
- By weight: light roast has slightly more caffeine (denser beans = more caffeine per gram)
- By volume (one scoop): dark roast may have slightly more caffeine (larger, lighter beans = more beans per scoop)
- In your cup: The difference is negligible — typically less than 5%
If caffeine is your primary concern, brew stronger coffee — add more grounds. Roast level won't move the needle meaningfully.
Which Roast Should You Choose?
If: You drink coffee black and want complexity
→ Light or medium roast. Single origin beans will show the most interesting flavors.
If: You drink coffee with milk or cream
→ Medium or dark roast. The bolder flavor holds up and isn't overwhelmed.
If: You have acid sensitivity
→ Dark roast. Longer roasting breaks down chlorogenic acids significantly.
If: You're making cold brew
→ Medium or dark roast. The long cold extraction softens bitterness while maintaining body.
If: You're pulling espresso
→ Medium to medium-dark. Traditional espresso uses dark roast, but specialty espresso uses medium.
If: You're just getting started
→ Medium roast. It's forgiving, familiar, and works with every brewing method.
Frequently Asked Questions
Does dark roast have more caffeine?
No — this is one of the most persistent coffee myths. Light roast has slightly more caffeine by weight. The difference is so small in a brewed cup that it's not worth factoring into your choice.
Is light roast more acidic?
Yes. Longer roasting degrades chlorogenic acids, reducing brightness and acidity. Light roasts are more acidic and brighter. Dark roasts are lower in acid and easier on sensitive stomachs.
Why does Starbucks taste so dark and bitter?
Large commercial roasters often over-roast coffee to create a consistent, bold flavor that disguises variation in green bean quality and holds up in milk-heavy drinks. Specialty roasters like Roast use lighter, more precise roast profiles to highlight the bean.
What does 'medium-dark' or 'full city' roast mean?
These are sub-classifications within the dark roast category. Full city sits between medium and dark — slightly oily surface, mild dark chocolate notes, still retaining some origin sweetness. 'French roast' and 'Italian roast' are at the darkest end.
Related Guides
Find Your Roast
Browse Roast's full lineup — light, medium, and dark — roasted fresh in small batches in Medford, NJ.