Weight in grams per square metre is the number people look at most when buying towels, and the one that is least understood. Nearly every guide reads it as a scale of quality: more grams, more absorbency, more luxury. The reality is more useful. Grammage tells you how much cotton there is in each square metre: more pile means more yarn surface and therefore more water the towel can hold. What it does not tell you on its own is how that pile is built, and it does tell you how much the towel weighs in every load and how much water has to be dried. Between 450, 500 and 600 g/m², the right choice depends less on the property's star rating than on how you wash, how you dry and how you are billed.
What grammage measures, and what it does not
Grammage is mass per unit area: the grams one square metre of fabric weighs. In Europe it is determined with standard UNE-EN 12127, by weighing specimens cut from conditioned fabric. Three practical things follow:
- A towel's weight is grammage × area. A 70 × 140 cm towel is 0.98 m²: at 450 g/m² it weighs about 441 g, and at 600 g/m², about 588 g. You can check it on a kitchen scale.
- Tolerance is agreed, not regulated. No sales standard fixes how far a towel may deviate from its stated weight. Ask your supplier for the tolerance, and whether the figure refers to the new towel or to the towel after its first washes.
- Grammage says nothing about how the pile is built. Two towels at 500 g/m² can have different yarns, pile and finishes, and behave very differently in the bathroom and in the laundry.
More grammage does absorb more, but construction rules
With the same construction, a heavier towel absorbs more: there is more pile, more loops and more yarn surface for water to sit in. A 600 g/m² bath towel holds more water than a 450 of the same size, which is why the guest notices the difference. What does not hold is the simplistic reading that grammage explains everything: how much a towel absorbs, and how fast, also depends on loop height, on yarn twist — a low-twist pile wicks sooner — on the spinning method and on the factory finishes. Two different things are worth keeping apart: a study published in 2025 in Scientific Reports measured the effect of increasing the fabric's thread density and found that packing the ground weave tighter lowered absorbency and softness while raising tensile strength and shrinkage. Packing the ground weave is not the same as adding pile on top: different variables, pulling in different directions.
There is a second effect that confuses many buyers: new towels carry residues from the finishing process that reduce absorbency, and those residues wash out over the first few cycles. A towel that "does not dry" on day one is telling you nothing yet about its grammage or its quality. Wash it before you judge it.
High grammage also gives you body: a thicker, heavier towel in the hand, which guests read as better. That perception is real, and it comes with genuinely more absorbent capacity; the decision is not whether it absorbs more, but whether that is worth what it costs to wash and dry.
What it weighs in the laundry
The cost that does grow with grammage is weight, and the sum is simple:
extra kilos per load = difference in grammage × square metres of terry in the load
One change for four guests with four 70 × 140 towels and four 50 × 100 towels comes to 5.92 m² of terry. On that load:
| Step | Difference in grammage | Extra kilos per change |
|---|---|---|
| From 450 to 500 g/m² | 50 g/m² | 0.30 kg |
| From 500 to 600 g/m² | 100 g/m² | 0.59 kg |
| From 450 to 600 g/m² | 150 g/m² | 0.89 kg |
Substitute your own sizes and guest numbers: with a 100 × 150 towel or a bath mat, the area grows and so does the difference. Multiply by the changes in a year and you have the extra kilos you will move across the whole life of the towels.
But before doing that sum, look at your invoice. Some hospitality laundries charge by the kilo and others by the piece, and some publish both rates. If you pay by the piece, grammage does not change your wash bill: a hand towel costs the same at 450 as at 600. If you pay by the kilo, or you wash yourself, it does. It is the fact that changes the decision most, and the one almost no guide mentions.
What it takes to dry
Drying is the other half of the cost, and grammage counts there even if you pay by the piece, because it eats into the capacity of whoever dries. After extraction, the water a towel retains is measured as a percentage of its dry weight: more grams of cotton, more water to evaporate.
extra water per load = extra kilos × your machine's residual moisture
Residual moisture depends on extraction g-force and appears on the machine's data sheet. Evaporating one kilo of water takes, by physics alone, about 0.63 kWh as an absolute minimum, and a real dryer spends more, because it also heats the drum, the air and the linen.
The practical consequence: if you go from 450 to 600 and keep the same programme and the same dryer time, the heavier towel can come out dry on the outside and damp in the folds and hems.
Why they smell damp between bookings
You often hear that a damp smell is a matter of grammage. That is only partly true. The typical smell of badly dried laundry has been studied: work published in 2012 in Applied and Environmental Microbiology identified the compound that produces it and the bacterium that generates it, Moraxella osloensis, which is highly tolerant of drying out — one reason it survives the drying process. A 2020 review in Microorganisms gathers the rest of the causes: low-temperature washes that do not reduce the microbial load, detergent and fragrance residues that stay on the fibre, biofilms in the detergent drawer, the door seal and the machine filter, and laundry left in humid conditions after washing.
Grammage comes in through one of those doors only: the more water the towel holds, the easier it is to put it away before it has dried completely. If your towels smell, check in this order:
- That they come out fully dry, in the folds and hems too, and that they cool before being folded.
- The wash temperature the care label allows, rather than staying on cold programmes out of habit.
- The detergent and fragrance dose: what is left over stays on the fibre.
- The machine: door seal, drawer and filter clean.
- The cupboard: ventilated, with nothing put away warm or damp.
- And only then, the grammage: if all of the above is right and your drying cannot do more, dropping the weight is a real solution.
Price, without textbook percentages
There is a widespread idea that the price gap between 500 and 600 g/m² is a fixed percentage. In the price lists published by hospitality suppliers that we checked, the gap depends on the line and the size: it runs from practically nothing to about a quarter, and in one size a 600 towel from one line costs the same as a 500 from another. There is no percentage that holds for everything. Compare like for like on size, ask about the pile, and weigh a sample.
As a reference for how that figure should be published, every item in our towel range states composition, weave, weight and sizes.
How to choose between 450, 500 and 600
| If… | It tends to suit you |
|---|---|
| Your laundry charges by the kilo, or you wash and dry yourself with capacity to spare | 450 or 500 |
| High rotation, short stays, departure and arrival on the same day | 450 or 500 |
| You pay for washing by the piece and drying is comfortable | 500 or 600, where the guest will notice |
| The large bath towel | The highest weight in your bathroom |
| Hand and face towels | The lowest: they change the experience little and the load a lot |
And one note that saves arguments: before raising grammage because of the reviews, try a well-built, well-washed towel in the weight you already have. Often the complaint was not about grams. The sizes and weights of every towel are in the towel size guide, and to turn kilos into cost per use, see the cost-per-use calculation.