Verify Four Facts Before Doing Any Arithmetic

Record these four facts first:

1. Chemistry: lithium metal or lithium alloy—not rechargeable lithium ion.
2. Exact component cell: manufacturer and complete model number.
3. Lithium content per cell: a model-specific value expressed in grams.
4. Component-cell count: the number of those cells in one exact battery design.

If the per-cell content is missing, do not replace it with a voltage, capacity, Wh or weight estimate. Request the value and its source from the responsible manufacturer or document issuer.

What Lithium Content Means for Battery Shipping

In this article, lithium content is the grams-based value used for a lithium-metal or lithium-alloy cell. Aggregate lithium content describes a battery made from component cells.

The IATA Guidance Document for Lithium Batteries and Sodium Ion Batteries—2026 defines aggregate lithium content as the sum of the grams of lithium content in the cells comprising a battery. The current FAA Interactive Guide to Shipping Lithium Batteries—2026 presents the same sum-of-cell-values concept in its U.S. air-shipping guidance.

The physical level matters:

• A cell is one encased electrochemical unit.
• A component cell is a cell contained in a battery.
• A battery is two or more cells electrically connected and fitted with the devices necessary for use; packs, modules or assemblies meeting that definition are treated as batteries for transport purposes.
• Aggregate lithium content per battery is the sum of the verified lithium content of its component cells.

Commercial names are not enough to establish these facts. A product described as a “coin battery,” “primary battery,” “battery pack” or “backup battery” still needs an exact manufacturer, model, chemistry and design-level record.

IATA and FAA documents are useful guidance, but they are not substitutes for the controlling regulations, required training or a shipment-specific review. The applicable requirements can depend on transport mode, origin, destination, configuration, condition, quantity and the operators involved.

Lithium Content Is Not Watt-Hours

Watt-hours and lithium content answer different questions for different battery chemistries.

The Wh relationship Wh = V × Ah does not produce grams of metallic lithium. Voltage, Ah and mAh describe electrical characteristics. Runtime is a product-performance result. Total cell weight includes the case and other materials. Package weight includes still more components. None of those figures states the lithium content of the exact lithium-metal cell.

For example, a supplier may provide 3 V and 1,500 mAh for a primary cell. Those numbers do not authorize a conversion to grams of lithium. Ask for the model-specific lithium-content value instead.

If the battery is rechargeable lithium ion, use the separate guide to lithium battery Watt-hour calculation. Do not carry the Wh formula into a lithium-metal content review.

Obtain the Per-Cell Value from the Responsible Source

The arithmetic is simple only after the source data is reliable. Start with the exact cell manufacturer and model, then trace the content value to a record that covers that model.

Useful evidence may include:

1. the cell manufacturer's model-specific specification;
2. a responsible technical declaration from the manufacturer;
3. the matching battery or product specification showing the installed component cells;
4. a model-matched UN 38.3 test summary for the cell or battery, interpreted at the physical level it describes; and
5. an SDS/MSDS that supports the same chemistry and identity.

These documents do not perform the same function. An SDS/MSDS can support the review, but its presence does not automatically prove the cell value, the UN 38.3 status or transport acceptance. A generic test summary for a product family also cannot resolve the content of an exact model unless the record clearly covers that design type.

The IATA 2026 guidance lists chemistry, mass, Watt-hour rating or lithium content, physical description and model numbers among the minimum cell-or-battery description fields in a test summary. A cell-model summary may support the per-cell value; a battery-model summary may instead state the battery-level aggregate value. This makes identity and physical-level matching essential.

Record the value exactly as supplied, including:

• the unit, normally grams;
• the number of decimal places;
• whether it applies to one cell or one battery;
• the manufacturer and full model number;
• the document name, revision and date where available; and
• the responsible source or issuer.

Stop the review when the only evidence is a marketplace listing, an unlabeled image, a similar model or a broad product-family brochure. Do not fill the gap with an estimate.

Calculate Aggregate Lithium Content for One Battery

For identical component cells, use:

Aggregate lithium content per battery = verified lithium content per cell × number of component cells

For a documented design containing different component-cell models, use:

Aggregate lithium content per battery = sum of the verified lithium content of every component cell

Follow this auditable sequence:

1. Identify the exact battery model.
2. List each component-cell manufacturer and model.
3. Record the verified lithium content per cell in grams.
4. Record the number of each component-cell model in one battery.
5. Multiply each per-cell value by the applicable count.
6. Add the subtotals if the design contains more than one cell model.
7. Label the answer aggregate lithium content per battery.
8. Compare it with the manufacturer's declared battery value.
9. Hold the review and request clarification if the values do not agree.

Do not infer the cell count from the exterior shape of a sealed product. The battery specification or responsible manufacturer should establish the internal design.

Identical-cell example

Assume a manufacturer record states that the exact component cell contains 0.25 g of lithium and that one battery contains four identical cells:

4 × 0.25 g = 1.00 g aggregate lithium content per battery

Mixed-cell example

Assume a documented battery design contains two cells declared at 0.30 g each and one different cell declared at 0.50 g:

(2 × 0.30 g) + (1 × 0.50 g) = 1.10 g aggregate lithium content per battery

Use this method only when the mixed-cell design and every per-cell value are documented for the exact model. These examples demonstrate arithmetic; they are not real manufacturer ratings, classifications or approvals.

Cell, Battery and Shipment Totals Are Different Numbers

A correct number can still cause a shipping error if it is entered at the wrong physical level.

Multiplying 1.00 g per battery by 60 batteries gives a useful internal shipment total of 60.00 g. It does not change the aggregate lithium content of each battery: each battery remains 1.00 g.

Keep all units and labels visible. Avoid an unlabeled field such as Lithium: 60, which does not show whether the number means grams per cell, grams per battery, batteries per package or a shipment total.

Worked Lithium-Content Examples

All values below are fictional and assumed to come from responsible, model-specific manufacturer information.

The 2.10 g result must remain 2.10 g. Do not round it down to 2 g to obtain a preferred regulatory branch. Retain the source precision, reconcile the result with the manufacturer's declaration and review the actual current pathway.

No example above establishes a UN number, packing-instruction section, mark, label, document or carrier decision.

What the 1 g and 2 g Air Decision Points Do—and Do Not Mean

The IATA 2026 lithium-metal battery flowchart and the FAA 2026 guide separate lithium-metal cells at 1 g and batteries at 2 g within specified air-transport pathways.

This distinction requires the correct physical level:

• compare the lithium content of one cell with the cell decision point;
• compare the aggregate lithium content of one battery with the battery decision point; and
• keep package and consignment quantities separate.

The values are not universal exemptions. A cell at or below 1 g or a battery at or below 2 g is not automatically non-dangerous, unrestricted or accepted for air transport. The result still sits within a larger review that may include:

• UN3090 or UN3091 configuration;
• standalone, packed-with-equipment or contained-in-equipment status;
• UN 38.3 design-type testing;
• the applicable packing instruction and section;
• number of cells or batteries and number of packages;
• package construction and protection;
• marks, labels and documents;
• battery condition;
• origin, destination and transit requirements;
• State and operator variations; and
• airline, airport and handling acceptance.

Other modes and jurisdictions require their own current review. A 2.10 g battery is above 2 g; rounding cannot move it into a ≤ 2 g branch. Conversely, being above a decision point does not mean that every transport option is prohibited—it means the shipment must be assessed under the applicable pathway.

Use the dedicated UN3090 vs UN3091 guide for the configuration decision. Do not select a UN entry from lithium content alone.

Button Cells and Equipment Need Separate Checks

“Button” or “coin” describes a physical form, not a universal shipping exception. Confirm whether the item is one cell or a battery and whether it is shipped by itself, packed with equipment or contained in equipment.

Current provisions can contain narrowly defined treatments for particular configurations and quantities. For example, the IATA 2026 guidance notes a test-summary exception for button cells installed in equipment, including circuit boards, and describes limited battery-mark exceptions in certain contained-in-equipment situations. Those statements do not remove the need to verify chemistry, cell or battery identity, lithium content, equipment configuration, quantity, package count and all other applicable conditions.

A data logger, circuit board, meter or tracking device may use a button cell, but the product name does not answer:

• whether the electrochemical unit is a cell or a multi-cell battery;
• whether it is installed, packed with the equipment or shipped separately;
• how many cells or batteries are in each item and package;
• whether the exact design is covered by the supplied test summary; or
• whether a specific operator will accept the shipment.

Treat every exception as condition-dependent and verify the current rule set for the actual shipment.

Compare the Value with the Battery Label and Transport Records

Use the arithmetic as part of a model-matched identity review.

A difference is not resolved by choosing the smaller or more convenient number. Check whether the mismatch comes from a different cell revision, different battery configuration, unit error, copied product-family record or simple arithmetic mistake. The responsible manufacturer or document issuer must confirm or correct the source information.

Common Lithium-Content Errors

1. Converting Ah, mAh or Wh into grams of lithium

Electrical ratings do not provide the model-specific metallic-lithium mass. Obtain the lithium-content value from the responsible source.

2. Using total cell weight as lithium content

The gross mass of a cell includes the case and other materials. It is not the same as lithium content.

3. Copying a value from a similar model

Product families may contain multiple cell constructions. Match the complete model and revision.

4. Declaring one cell's value as the battery total

A multi-cell battery requires the sum of all documented component-cell values.

5. Calling a shipment total “per battery”

Quantity arithmetic is useful for reconciliation, but it does not change the design-level value of each battery.

6. Using the wrong product variant

Products with the same commercial name can contain different battery models or cell suppliers.

7. Mixing milligrams and grams

Convert the units explicitly and retain the original source record. 1,000 mg = 1 g.

8. Dropping decimal precision near a decision point

Do not round 2.10 g to 2 g. Preserve enough precision to show the actual value.

9. Treating lithium content as proof of UN 38.3 testing

Lithium content is one design fact. It does not show which tests were performed or whether the exact design type passed.

10. Assuming a value at or below 1 g or 2 g guarantees acceptance

Configuration, quantity, packaging, documentation, condition, route and operator requirements still apply.

What Lithium Content Cannot Decide

Lithium content is an important input, but it cannot independently determine:

• UN3090 versus UN3091;
• standalone, packed-with-equipment or contained-in-equipment treatment;
• whether the exact design passed UN 38.3;
• the applicable packing instruction and section;
• packaging, terminal protection, marks, labels or documents;
• quantity, package-count or net-mass limits;
• whether prototype, low-production, used, returned or waste provisions apply;
• whether a battery is damaged, defective or recalled;
• whether air, sea, courier, road or rail transport is available; or
• whether an authority, carrier, port, airport, handling agent, customs office or destination party will accept the shipment.

Use the lithium battery packaging review, marks and labels guide and shipping documents checklist for their respective decisions. If the battery is damaged, safety-defective or recalled, stop the ordinary workflow and use the separate damaged or defective lithium battery review.

Pre-Enquiry Lithium-Content Verification Checklist

Before requesting a route or carrier review, confirm that:

• Lithium-metal or lithium-alloy chemistry is established.
• The cell, battery and product manufacturers and exact models are recorded.
• The per-cell lithium-content value is expressed in grams.
• The per-cell value has a responsible, model-specific source.
• The component-cell count matches the exact battery design.
• Mixed cell models, if any, are individually documented.
• The aggregate calculation has been checked without premature rounding.
• The result is labelled per battery, not per package or shipment.
• The battery specification and test-summary identity fields agree.
• The product configuration and battery quantity are recorded separately.
• Battery condition, package facts, transport mode, pickup point and destination are known.
• Every unresolved mismatch has been returned to the manufacturer or document issuer.
• No classification, booking or acceptance promise has been made from lithium content alone.