Glass Composition Calculator

Example data table

Formula used

• Normalization (optional): wt%_norm,i = 100 × wt%_i / Σ(wt%).
• Moles per 100 g: n_i = (wt%_i × 1 g) / M_i, because wt% refers to grams in 100 g glass.
• Molar percent: mol%_i = 100 × n_i / Σ(n).
• Modifier-to-former ratio: (Σ modifiers wt%) / (Σ formers wt%).
• Batch estimate: raw mass = required oxide mass / oxide fraction in that raw material.

How to use this calculator

1. Enter your oxide weight percentages for the target glass.
2. Enable normalization if your total is not exactly 100 wt%.
3. Click Calculate to view wt%, mol%, and quick indices.
4. Optionally enable batch estimation to get a first-pass raw mix.
5. Download CSV or PDF to save your results for records.

Glass composition guide

1) What “oxide basis” means

Most industrial glass recipes are expressed as oxide weight percentages (wt%). Each oxide represents the final glass chemistry after decomposition and refining. This calculator treats your inputs as target oxides in the finished glass, then converts them into moles and mol% to show network balance.

2) Typical soda‑lime ranges

Common container and float glass often targets high silica for durability and stiffness, with modifiers to reduce melt viscosity. A practical window is roughly 70–74 wt% SiO2, 12–16 wt% Na2O, and 8–12 wt% CaO, with 1–3 wt% Al2O3. Small MgO can improve stability and devitrification resistance.

3) Why mol% matters for structure

Weight percent can hide structural impact because heavy oxides contribute fewer moles. Molar percent better reflects how many oxide units participate in the network. For example, a small wt% of an alkali can represent a larger mol% share and noticeably lower viscosity or chemical resistance.

4) Formers, modifiers, intermediates

Network formers (SiO2, B2O3) build the backbone. Modifiers (Na2O, K2O, CaO, MgO) break bridging oxygen links, opening the structure for easier melting. Intermediates (Al2O3, TiO2, ZrO2, ZnO) can strengthen the network or improve chemical durability when balanced with enough modifiers.

5) Interpreting the modifier‑to‑former ratio

The modifier‑to‑former ratio is a quick indicator of how “open” the network might be. Lower ratios generally align with higher viscosity, higher softening points, and improved durability. Higher ratios tend to lower melting temperatures but may increase leaching risk in aggressive environments.

6) Batch estimation and gas release

When you enable batch estimation, carbonate sources (like soda ash and limestone) add extra mass that later leaves as CO2 during melting. That is why total batch input can exceed 100 kg for 100 kg glass. Use the batch as a first pass, then adjust for raw purity, fining agents, and process losses.

7) Practical adjustment strategy

If the melt is too viscous, modestly increase alkali or add B2O3, then re-check durability indices. If chemical resistance is weak, raise SiO2 and Al2O3 and reduce total alkali. Always keep sums consistent and compare changes in mol% rather than wt% alone.

8) Reporting and traceability

Exporting results to CSV or PDF helps maintain batch traceability and supports quality audits. Record oxide wt%, mol%, and key ratios for each trial melt. Over time, a small dataset can reveal how composition trends affect softening behavior, working range, and product performance.

FAQs

1) Should I enter raw materials or oxides?

Enter target oxides for the finished glass. If you need a starting raw mix, enable the batch estimate to convert key oxides into common raw materials using stoichiometric fractions.

2) What if my total is not 100 wt%?

Turn on normalization to scale your inputs to 100 wt%. If you want a strict recipe, disable normalization and adjust values until the total is within about ±0.5 wt% of 100.

3) Why do I see mol% different from wt% trends?

Mol% reflects the number of oxide units, not their mass. Heavy oxides contribute fewer moles per unit weight, so a small wt% can have a smaller mol% impact, and vice versa.

4) Does the batch estimate include losses and fining agents?

No. It is a stoichiometric starting point. Real batches require adjustments for raw purity, volatilization, fining agents, cullet fraction, and furnace-specific yield.

5) How should I use the modifier‑to‑former ratio?

Use it to compare recipes quickly. Higher values usually indicate easier melting and lower viscosity, while lower values often suggest higher durability and higher softening temperatures.

6) Can I model specialty oxides not listed?

This version focuses on common oxides. You can extend the oxide list by adding entries with molar mass and role, then the calculator will include them in normalization, molar conversion, and exports.

7) Why is lead glass shown only as an example row?

The table illustrates how compositions can differ by application. If you use PbO, enter it in the form and interpret results carefully, considering safety, regulations, and your process requirements.

Accurate glass batches start with balanced oxide percentages today.