Free Tool
GSM Calculator for Paper
Find the GSM of any paper from its weight and size — or use the 10×10 cm sample method. Free, instant, in mm, cm, inches and kg.
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- ✓ mm, cm, inch, gram & kg
- ✓ Your numbers are never stored
What is a GSM calculator?
A GSM calculator works out the GSM — grams per square metre — of a paper from how much a known size of it weighs. GSM is the standard way to describe paper weight: 80 GSM is ordinary copier paper, 120–170 GSM suits brochures and bags, and 300 GSM and above is card and board. If you have a sheet of paper and no label, or a supplier's GSM looks wrong, weighing a sample and using this calculator tells you the real number in seconds.
GSM formula for paper
In grams and centimetres: GSM = Weight (g) × 10,000 ÷ (Length cm × Width cm)
In kilograms and metres (many sheets): GSM = Weight (kg) × 1,000 ÷ (Length m × Width m × Number of sheets)
10 × 10 cm sample: GSM = Weight of the sample (g) × 100
Weight of a sheet: Weight (g) = Length (m) × Width (m) × GSM
Unit conversion: 1 cm = 10 mm, 1 inch = 25.4 mm and 1 m = 1,000 mm. The calculator converts length and width separately, so you can mix units.
How to calculate GSM of paper — 3 easy ways
1. The 10 × 10 cm sample method (easiest)
Cut an exact 10 cm × 10 cm square, weigh it in grams on a digital scale and multiply by 100. That is the GSM.
2. Weigh one sheet of known size
Weigh a single sheet and use the formula with its length and width. Best for large sheets when you have a bigger scale.
3. Weigh a stack of sheets (most accurate)
Weigh many identical sheets together and divide by the number of sheets. Averaging over many sheets cancels out small scale errors.
Using the calculator
- 1Pick the tab for what you want to find: GSM, the 10×10 cm sample method, weight, length or width.
- 2Enter the length and width of the sheet and choose MM, CM, INCH or M for each.
- 3Enter the weight (in grams or kilograms) and how many sheets that weight is for.
- 4Press Calculate and read the result instantly.
GSM calculation examples
- Sample method: a 10 × 10 cm piece weighs 0.8 g, so GSM = 0.8 × 100 = 80.0 GSM.
- One A4 sheet: 297 × 210 mm weighing 4.5 g. Area = 0.297 × 0.210 = 0.06237 m², so GSM = 4.5 ÷ 0.06237 = 72.2 GSM.
- A stack: 500 A4 sheets weigh 2.5 kg. GSM = 2.5 × 1,000 ÷ (0.297 × 0.210 × 500) = 80.2 GSM.
- Inches: a 12 × 18 inch sheet weighs 45 g. That is 304.8 × 457.2 mm, so GSM = 322.9 GSM.
GSM chart: what each paper weight is used for
A rough guide only — exact use depends on the paper type and finish.
| GSM | Typical use |
|---|---|
| 60–90 GSM | Standard copier and printer paper, notebooks, light carry bags |
| 100–170 GSM | Brochures, flyers, posters, shopping and garment bags |
| 170–250 GSM | Premium and laminated bags, covers, lightweight cardstock |
| 200–300 GSM | Greeting cards, invitations, luxury gift bags |
| 300+ GSM | Heavy packaging, business cards, cardboard |
A4 sheet weight by GSM
Weigh a plain A4 sheet and compare it with this table to estimate its GSM, or use it to check what a ream should weigh.
| GSM | One A4 sheet | 500 sheets (1 ream) |
|---|---|---|
| 60 GSM | 3.74 g | 1.87 kg |
| 70 GSM | 4.37 g | 2.18 kg |
| 80 GSM | 4.99 g | 2.49 kg |
| 90 GSM | 5.61 g | 2.81 kg |
| 100 GSM | 6.24 g | 3.12 kg |
| 120 GSM | 7.48 g | 3.74 kg |
| 150 GSM | 9.36 g | 4.68 kg |
| 170 GSM | 10.60 g | 5.30 kg |
| 200 GSM | 12.47 g | 6.24 kg |
| 250 GSM | 15.59 g | 7.80 kg |
| 300 GSM | 18.71 g | 9.36 kg |
A4 = 210 × 297 mm. Flat sheets; real paper varies slightly by mill and moisture.
GSM for paper bags
Paper bags are made across a wide GSM range. Light carry bags for pharmacy and grocery use roughly 60–80 GSM, everyday retail and food bags 80–120 GSM, garment and shopping bags 120–170 GSM, and premium or laminated bags 170–300 GSM. Higher GSM is not automatically stronger — the paper type, bag size and handle matter too.
Not sure which to choose? Read our paper bag GSM guide, get a budget figure from the Paper Bag Price Calculator, or ask us for an exact quote.
Who uses a GSM calculator?
Printers and packaging makers use it to verify supplier paper, buyers use it to check a quotation, paper traders use it to convert between sheets and kilograms, and students and designers use it to understand what “80 GSM” or “300 GSM” really means.
Need the weight and cost of paper instead? Try the Paper Weight Calculator.
Learn more
GSM Calculator: Frequently Asked Questions
GSM stands for grams per square metre. It tells you how much one square metre of the paper weighs. 70 GSM paper means a full square metre of it weighs 70 grams, and 300 GSM paper weighs 300 grams per square metre. Higher GSM means heavier, thicker paper.
Weigh the paper in grams, work out its area in square metres, and divide: GSM = weight (g) ÷ area (m²). If you measure in centimetres, GSM = weight (g) × 10,000 ÷ (length cm × width cm). The calculator above does this for you in mm, cm, inches or metres.
GSM = weight in grams × 10,000 ÷ (length in cm × width in cm). For many sheets in kilograms and metres: GSM = weight in kg × 1,000 ÷ (length in m × width in m × number of sheets).
Use the 10 × 10 cm sample method. Cut an exact 10 cm × 10 cm square (100 cm²), weigh it in grams on a digital scale, and multiply by 100. For example, a sample weighing 0.8 g is 80.0 GSM. Use the “10×10 cm Sample” tab above to do it instantly.
Weigh the whole stack, count the sheets, and use GSM = weight (kg) × 1,000 ÷ (length m × width m × sheets). For example, 500 sheets of A4 (0.297 × 0.210 m) weighing 2.5 kg give about 80.2 GSM. Weighing many sheets together is more accurate than weighing one.
Everyday office copier and printer paper is usually between 70 and 100 GSM. One A4 sheet (210 × 297 mm) weighs about 4.37 g at 70 GSM, 4.99 g at 80 GSM and 6.24 g at 100 GSM.
GSM is a weight per square metre, so it does not change with the size of the sheet. The weight of a sheet depends on both its GSM and its size. A bigger sheet of the same 80 GSM paper weighs more, but its GSM is still 80.
Higher GSM generally means heavier and thicker paper, but strength and thickness also depend on the paper type, fibre and finish. Two papers with the same GSM can feel different, so GSM is a useful starting point rather than the whole specification.
Multiply the sheet area in square metres by the GSM to get grams per sheet, multiply by the number of sheets and divide by 1,000 for kilograms. Our Paper Weight Calculator and the “Weight” tab above do all of it, including the paper cost from your rate per kg.
Light carry bags for pharmacy and groceries commonly use about 60–80 GSM, restaurant, bakery and everyday retail bags about 80–120 GSM, garment and shopping bags about 120–170 GSM, and premium or laminated bags about 170–300 GSM. Kyara Packaging's catalogue covers 60–300 GSM. The right choice depends on bag size, what it carries and the paper type.
The maths is exact, so accuracy depends on your measurements. Use a scale that reads to at least 0.01 g for small samples, cut the sample square, and weigh several identical sheets together when you can. Moisture in the paper can also shift the weight slightly.
Yes. Choose MM, CM, INCH or M for length and width, and GRAM or KILOGRAM for weight. For example, a 12 × 18 inch sheet weighing 45 g is about 322.9 GSM.
Yes. It is free, needs no sign-up and runs in your browser. The numbers you enter are not stored.
More questions? Contact us →