Loading density (sometimes called linear charge concentration) is one of the fastest ways to sanity-check a loading plan, document what was actually loaded, and communicate clearly between the blaster, loader, and engineer. In simple terms, it tells you:
How much explosive is in the hole per unit length (mass per foot or mass per meter)?
That one number helps you compare products (bulk vs. packaged), hole diameters, and charge configurations—without getting lost in total pounds per hole. To make this easy in the field, we built a Loading Density calculator inside the PETS Toolbox. PETS Toolbox – Loading Density Calculator
What “Loading Density” Means (and why it matters)
Loading density is typically reported as:
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lb/ft (US customary)
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kg/m (SI)
It’s useful because it’s independent of hole length. If you know your target linear load, you can quickly evaluate whether a charge column is in the right range for the plan—especially when switching:
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Explosive type (emulsion, ANFO, water gel, packaged product)
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Diameter (2.5”, 3”, 4”, 6.75”, etc.)
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Coupling (fully coupled vs decoupled cartridges)
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Decking (multiple charge segments separated by inert decks)
What you’ll need before you open the calculator
Have these items from your approved blast plan or loading sheet:
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Explosive product density (as supplied / as loaded)
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Effective charge diameter (borehole ID or cartridge OD)
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Charge column length (per deck, if decked)
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Optional: Units you want (lb/ft or kg/m)
If you’re loading decked holes, treat each deck separately first—then you can roll up totals later for documentation.
Step-by-step: Using the PETS Loading Density Calculator
Inside the PETS Toolbox calculator:
Step 1 — Select units
Choose lb/ft or kg/m based on your job documentation requirements.
Step 2 — Enter your explosive density
Input the density you’re using for that product (as loaded).
Tip: If you’re switching from bulk to packaged, density often changes—don’t assume they’re the same.
Step 3 — Enter your charge diameter
Use the effective charge diameter:
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Bulk in the borehole → typically borehole diameter (if fully coupled)
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Cartridges → cartridge outside diameter (decoupled charge)
Step 4 — Enter charge column length (optional, depending on the tool)
Some workflows only need density + diameter to compute lb/ft (because linear loading comes from cross-sectional area × density).
If the calculator asks for column length, enter the charge length per deck to compute the total charge per deck and/or validate the linear load.
Step 5 — Read the results
Your key outputs usually include:
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Loading density (lb/ft or kg/m)
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(Optional) Charge per deck/charge per hole if length is included
Use loading density for quick checks, like:
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“Is my decoupled cartridge load dramatically lower than expected?”
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“Did the bulk product’s effective density change today?”
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“Does Deck #2 match the planned linear load?”
Common mistakes (and how PETS helps you avoid them)
1) Mixing diameters
Borehole diameter ≠ cartridge diameter. If you enter the wrong one, the loading density can be off substantially.
2) Ignoring decoupling
Decoupled charges reduce the effective cross-sectional area, thereby reducing the linear load even if the product density remains the same.
3) Treating bulk density as constant
Moisture, prill condition, temperature, gassing behavior, and product handling can shift effective density.
4) Not separating decks
Each deck can have a different linear load. Treat them as separate charge segments for better documentation and QA/QC.
Best practice: How to use loading density safely (commercial mindset)
Loading density is a documentation and verification tool—it should support your approved blast plan, not replace it. Use it to:
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Confirm the loader is matching the plan
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Identify outliers before tying-in
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Improve shot records and post-blast review
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Communicate changes when products or diameters change
