Tonnage Calculator: precise material weight, cost, and coverage in a few clicks
Whether you’re topping a driveway, pouring base course under pavers, or pricing a bulk delivery, you need one number before anything else — the tonnage. This guide shows you how a tonnage calculator turns length, width, depth, and unit weight into an exact order quantity you can trust.
What is a tonnage calculator?
A tonnage calculator converts your project dimensions and the material’s unit weight into total weight. You enter length, width, and depth or directly enter area and volume. Select or enter the material’s unit weight. The calculator outputs tons, pounds, or kilograms and can estimate cost when you add price and waste.
Contractors use it for gravel, sand, crushed stone, asphalt millings, base course, topsoil, and similar bulk materials. Engineers use it to validate estimates before procurement. Homeowners love it because it saves over- or under-ordering headaches.
How the calculator works (formulas)
Under the hood it’s simple physics. Volume multiplied by unit weight equals mass. Then you convert mass into the unit you want (US tons, metric tons, pounds, or kilograms).
Core formulas
Area = Length × WidthVolume = Area × DepthMass = Volume × Unit Weight(e.g., ft³ × lb/ft³ = lb)Tons (US) = Pounds ÷ 2000Metric tons (t) = Kilograms ÷ 1000
The calculator handles unit conversions automatically, so you can mix inches for depth with feet for length and width without doing any math by hand.
Quick steps: get tons fast
- Choose your material. If available, use the supplier’s tested unit weight.
- Enter the project footprint: length and width or the total area.
- Enter the design depth. Compaction requires more material. Plan for waste.
- Review the result in tons. If needed, switch to pounds, kilograms, or metric tons.
- Enter your price per ton and waste percentage to see total cost.
Worked examples you can copy
Example 1 — Driveway gravel
You want 4 inches of gravel on a 60-ft by 12-ft drive. Assume a typical loose unit weight of 100 lb/ft³ for gravel.
- Area = 60 × 12 = 720 ft²
- Depth = 4 in = 0.333 ft
- Volume = 720 × 0.333 ≈ 239.8 ft³
- Weight = 239.8 × 100 ≈ 23,980 lb
- Tons (US) = 23,980 ÷ 2000 ≈ 12.0 tons
If the supplier recommends 5% waste for spread losses, order 12.6 tons.
Example 2 — Paver base (aggregate base course)
Patio footprint is 18 ft by 14 ft. Base course depth is 6 in. Typical estimating unit weight for aggregate base course is ~120 lb/ft³.
- Area = 18 × 14 = 252 ft²
- Depth = 6 in = 0.5 ft
- Volume = 252 × 0.5 = 126 ft³
- Weight = 126 × 120 = 15,120 lb
- Tons (US) = 15,120 ÷ 2000 = 7.56 tons
Example 3 — Topsoil for raised beds
You’re filling a rectangular bed 24 ft by 3 ft with 12 in of topsoil. Use 75 lb/ft³ for loose topsoil.
- Area = 24 × 3 = 72 ft²
- Depth = 12 in = 1 ft
- Volume = 72 ft³
- Weight = 72 × 75 = 5,400 lb
- Tons (US) = 5,400 ÷ 2000 = 2.7 tons
Unit weight vs. density (and why it matters)
In estimating, “unit weight” usually means bulk density expressed in weight per unit volume. Think of the whole blend as delivered to site, including voids between particles. Moisture, gradation, and compaction change it. That’s why the most accurate value comes from the supplier’s current test report.
When you want a reference point, use accepted “typical” values. The following institutions publish methods or tables that underpin practical estimates:
- US EPA material property references
- USDA & Land-Grant publications for soil bulk density
- State DOT manuals and handbooks for aggregates and asphalt base
Your calculator should let you change the unit weight field so you can plug supplier data right in. That keeps estimates grounded in reality.
Typical unit weights for common materials
Use this table as a starting point. These values represent mid-range “for estimating” numbers frequently seen across DOT, EPA/NTEA, and industry sources. Always verify with local suppliers.
| Material | Typical unit weight | Notes |
|---|---|---|
| Aggregate base course | ~120 lb/ft³ | Common for compacted base layers. |
| Gravel (general) | ~100–110 lb/ft³ | Varies with gradation and moisture. |
| Crushed stone | ~100 lb/ft³ | Broad estimating value. |
| Crushed granite | ~105 lb/ft³ | Slightly heavier than general crushed stone. |
| Concrete sand (C-33) | ~100 lb/ft³ | ASTM C-33 spec product. |
| Manufactured sand (DEP) | ~100 lb/ft³ | Compacted: ~115 lb/ft³. |
| Pea gravel | ~96 lb/ft³ | Rounded particles reduce packing. |
| River rock | ~100 lb/ft³ | Use supplier value for wide size ranges. |
| Sand (general) | ~100 lb/ft³ | Moisture content swings weight quickly. |
| Topsoil (loose) | ~75 lb/ft³ | Texture and organic content drive variation. |
| Crushed asphalt (milled stockpile) | ~45–60 lb/ft³ | Recycled material with high voids. |
Need to work in metric? Multiply lb/ft³ by 16.0185 to get kg/m³. For example, 100 lb/ft³ ≈ 1602 kg/m³.
Handy conversion chart
- 1 US ton = 2000 lb
- 1 imperial long ton = 2240 lb
- 1 metric ton (t) = 1000 kg
- 1 ft³ = 0.0283168 m³
- 1 yd³ = 27 ft³ = 0.764555 m³
- 1 in = 0.083333 ft
Estimate cost with waste and price
Pricing is simple once you’ve got tons. Two inputs finish the job: waste percentage and price per ton. Waste covers handling, spread losses, and compaction. Many suppliers suggest 5–10% depending on the product and weather.
Cost formula
Weight_with_waste = Base_weight × (1 + Waste% / 100) Total_cost = Weight_with_waste_in_priced_units × Price_per_unit
Let’s say your driveway project from Example 1 requires 12.0 tons. Price is $28 per ton. You plan 5% waste. Weight with waste becomes 12.6 tons. Total cost is 12.6 × $28 = $352.80.
Coverage: how much area per ton?
Coverage depends on depth and unit weight. Here’s a quick way to think about it. One ton equals 2000 lb. Divide by the unit weight to get cubic feet. Then divide by depth to get square feet of coverage.
Coverage per ton
Volume(ft³) per ton = 2000 ÷ (unit weight in lb/ft³) Coverage(ft²) per ton at depth d(ft) = Volume(ft³) ÷ d
Example: Gravel at 100 lb/ft³. Volume per ton = 2000 ÷ 100 = 20 ft³. At 3 inches (0.25 ft), coverage ≈ 20 ÷ 0.25 = 80 ft² per ton.
FAQ: quick answers
What’s the difference between ton and metric ton?
A US ton is 2000 lb. A metric ton (tonne) is 1000 kg or 2204.62 lb. An imperial long ton is 2240 lb.
How accurate are “typical” unit weights?
They’re meant for estimating. Moisture, gradation, and compaction change real-world numbers. When precision matters, ask your supplier for a current bulk unit weight measured using the ASTM C29 or AASHTO T 19 test method.
Do I enter depth compacted or loose?
Enter the finished design depth. Then add waste to cover compaction and placement losses.
Can I mix units?
Yes. Enter length and width in feet, depth in inches, and unit weight in lb/ft³. A good calculator handles conversions in the background.
Troubleshooting & pro tips
- Numbers feel too high? Check your depth. Three inches is 0.25 ft, not 0.3 ft.
- Numbers seem too low? Make sure you used the right unit weight. Was it compacted or loose?
- Ordering asphalt millings? Recycled stockpiles are airy. Expect far lower unit weight than dense gravel.
- Square and round areas. For circles, area = π × r². For triangles, area = 0.5 × base × height.
- Edge bands and curves. Break the site into rectangles or shapes you can compute, then sum them.
- Always round up deliveries. Short loads cost more than one slightly larger drop.
Mini-glossary
- Unit weight (bulk density): Weight per unit volume of a bulk material, including voids.
- Compaction: Mechanical densification that reduces air voids and increases unit weight.
- Waste: Allowance for losses during handling and installation.
- Void ratio: The space between particles. More voids mean lower unit weight for the same mineral.
Why a tonnage calculator pays for itself
You avoid guesswork. You order the right amount. You keep trucks moving and crews productive. Most of all, you protect your budget because every extra short load erodes margin. With a reliable calculator and credible unit weights you can quote quickly and build confidently.
