How to use a price per gram calculator
Price per gram = total price ÷ weight in grams.
Use the same currency for prices you compare. For example, 35 for 3.5 g is 10 per gram (35 ÷ 3.5 = 10). If another option is 60 for 7 g, its rate is about 8.57 per gram. These example figures only explain the calculation; they are not current or typical prices.
Common weights: gram and ounce fractions
An eighth, quarter and half are common names for fractions of an ounce. In everyday weight references, an ounce is often rounded to 28 g. The exact avoirdupois ounce is about 28.34952 g, so its exact fractions differ slightly from the rounded amounts.
| Amount | Common rounded weight | Exact ounce fraction |
|---|---|---|
| Gram | 1 g | — |
| Eighth (⅛ oz) | 3.5 g | ≈3.54369 g |
| Quarter (¼ oz) | 7 g | ≈7.08738 g |
| Half ounce (½ oz) | 14 g | ≈14.17476 g |
| Ounce | 28 g | ≈28.34952 g |
The weight calculator accepts the quantities shown in each row or a custom quantity. Its unit relationships use exact standard mass conversions.
Weight, volume and item units
Weight rows convert within the weight group, volume rows convert within the volume group, and item rows compare item counts. Prices entered in different groups are kept separate. The currency selector changes the displayed symbol; it does not convert exchange rates.
Volume and weight are different measurements: converting milliliters to grams requires the material's density, so this calculator keeps volume and mass comparisons separate.
| Unit | Equivalent relationship |
|---|---|
| 1 kilogram (kg) | 1,000 g |
| 1 pound (lb) | 453.59237 g |
| 1 ounce (oz) | 28.349523125 g |
| 1 gram (g) | 1,000 mg |
| 1 milligram (mg) | 0.001 g |
| 1 liter (L) | 1,000 mL |
| 1 milliliter (mL) | 0.001 L |
How to compare three prices by unit
- Enter each price, quantity, and unit.
- Choose units from the same category: weight, volume, or item count.
- Use one currency throughout. The lower displayed unit price is the lower numeric rate for that category.
This is a numeric comparison only. The calculator does not show market averages, product listings or seller recommendations.
Weight and price-per-gram questions
How many grams are in an eighth?
An eighth is commonly rounded to 3.5 g. One exact eighth of an avoirdupois ounce is about 3.54369 g.
How many grams are in a quarter ounce?
A quarter ounce is commonly rounded to 7 g. The exact quarter of an avoirdupois ounce is about 7.08738 g.
How many grams are in an ounce?
An ounce is commonly rounded to 28 g in these weight conventions. An exact avoirdupois ounce is 28.349523125 g.
How do I compare price per gram?
Divide each price by the matching weight in grams. For example, 35 ÷ 3.5 g = 10 per gram. Use the same currency for each price.
Can I compare prices entered in different currencies?
No. The currency selector changes the symbol shown by the calculator; it does not convert exchange rates. Convert both prices to the same currency first.
Does this calculator show current local or average prices?
No. It calculates only from the prices and weights you enter. It does not provide live market data or price estimates.