How to use this calculator
- Enter or choose paper grammage.
- Enter or choose sheet width.
- Enter or choose sheet length.
- Enter or choose number of sheets.
- Enter or choose uS basis grade.
- The total weight updates as you type. Use Copy result or Share to keep it.
Method
Sheet (g) = Width (m) × Length (m) × GSM; Basis (lb) = GSM × Basis area (m²) × 500 ÷ 453.59237
- Basis area
- the grade’s basis sheet in square inches × 0.00064516 m²/in²
- 453.59237
- grams per pound (exact)
Worked example
- A4 area = 0.21 × 0.297 = 0.06237 m²; × 80 = 4.99 g per sheet.
- 500 sheets = 2.495 kg.
- Text basis 25 × 38 in = 0.6129 m²; 80 × 0.6129 × 500 ÷ 453.59 = 54.0 lb.
A ream of 80 GSM A4 weighs about 2.5 kg, and 80 GSM equals about 54 lb text weight.
What the result means
Pound weights only compare within the same grade: 80 GSM is about 21 lb bond but 54 lb text. GSM compares across all grades.
Assumptions and limits
- Basis weights use the standard US basis sheet sizes listed.
- Actual grammage varies within the mill’s tolerance, and moisture changes weight slightly.
Questions
Why is 20 lb bond lighter than 50 lb text?
They use different basis sheet sizes. 20 lb bond is about 75 GSM; 50 lb text is about 74 GSM, so they are almost the same paper.