Blueberries (fresh)

The only published measurement for a US cup of blueberries (fresh) is 148 grams. One source is not enough to publish it as this site’s figure, so it is shown below with where it came from and what is still missing.

Also called fresh blueberries, blueberries, blueberries frozen, frozen blueberries, whole blueberries, blueberries whole.

Blueberries are the first fresh berry on the site, and their density is a case study in why cup measurement fails for whole small round fruit. King Arthur publishes fresh or frozen blueberries at 140 to 170 grams per cup, a 21% spread the chart itself doesn't try to narrow. USDA's SR Legacy record (FDC ID 171711) sits at 148 grams per cup for raw blueberries, inside the KA range but near the lower end. The 148 figure implies a standard cultivated berry, about 1.36 grams each per USDA's own 50-berry portion, loose-filled without shaking. The 170 upper end likely reflects larger berries, denser packing, or a shaken cup that lets small round fruit settle deeper.

The physics is straightforward: blueberries are roughly 1 cm spheres that roll and settle. Fill a cup by scooping and air pockets are trapped between the spheres. Shake the cup and the berries reorganize, smaller ones sliding into the interstitial gaps between larger ones, and the whole population settling denser. Cultivar matters too. Wild lowbush blueberries are about half the size of cultivated highbush, and mixed-size populations pack denser than uniform ones because the small berries fill the gaps the large ones leave open. Water content of the berry itself doesn't move the density much because the water is inside each berry rather than in the space between them, but ripeness affects compressibility. Riper berries deform slightly under their own weight in the cup and pack denser than firm underripe ones.

Conversion sites publishing figures for fresh blueberries are all over the map. Values from 100 to 190 grams per cup appear across the top search results, with most sites not disclosing their measurement method or accounting for berry size. USDA's 148 and King Arthur's 140-170 range are the two authoritative anchors, and this entry publishes both without collapsing them to a single number that would misrepresent the physical variability.

Category assignment is milled: fresh whole small fruits behave like the fresh chunked fruits already on the site. Apple-slices sit at 109 g/cup and pineapple-diced at 165 g/cup, both solid water-containing pieces whose density is sensitive to fill method. The sugar category is reserved for small crystalline or particulate solids like sugars, salts, chocolate chips, and small dried fruits such as raisins and currants. Fresh blueberries have too much water content and too much fill-method sensitivity to belong there. Dried blueberries, coming later this session at 156 g/cup, will also be milled rather than sugar because they are larger and less crystalline than raisins.

Frozen blueberries are grouped with fresh in the KA row and in practice behave similarly for measurement. Frozen berries are stiffer and don't compress in the cup, but their density measured as loose fill is close to fresh loose fill. USDA doesn't distinguish frozen from fresh in the standard 148 g/cup portion, which is why this entry's synonyms include both.

The range publish is required by the standards: KA's 21% internal range alone exceeds the 10% milled tolerance, and adding USDA at 148 doesn't narrow it. Publishing a single figure would misrepresent the physical variability. Bakers should weigh their berries when recipe accuracy matters. A recipe calling for 1 cup could reasonably use anywhere from 140 to 170 grams depending on cultivar and technique, and that 21% range in berry mass changes filling volume, moisture release during baking, and final texture.

Confidence is low because sources genuinely disagree over tolerance, not because sourcing is weak. Both USDA and King Arthur are the primary authorities in this space, and both are cited transparently. The range is honest.