Bituminous Prime & Tack Coat Calculator
Prime or tack coat in gallons = the area in square yards × the application rate in gal/yd². The area box defaults to ft², so switch its unit to yd² or enter square feet and let it convert. 5,000 yd² of tack coat at 0.05 gal/yd² needs 250 gal, or 262.5 gal with 5% waste. Paving: Asphalt Calculator.
How it's calculated: Total material (gal) = area (converted to yd²) × application rate (gal/yd²), plus the waste allowance.
Result appears here
Fill in the fields and press Calculate.
Formula, calculation, assumptions and sources
Total material (gal) = Area (yd²) × Application rate (gal/yd²)
Run the calculation to see each step with your own numbers.
A 5,000 yd² surface, tack coat at 0.05 gal/yd² residual, 5% waste.
Quantity = 5,000 × 0.05 = 250 gal exact (≈946 L)
With 5%: order ≈ 262.5 gal
- A single, uniform application rate over the whole area entered. A large job with varying surface porosity may need a variable rate — follow a test-strip calibration.
- The rate entered is the RESIDUAL (net) application rate. If you're using a diluted emulsion, the as-sprayed (undiluted) rate is higher — check your emulsion's dilution ratio.
- Prime coat assumes a granular (untreated aggregate) base; tack coat assumes it's applied between two asphalt lifts or onto an existing asphalt/PCC surface — the choice only changes the typical-rate guidance shown, not the formula.
- Surface preparation, cure/break time and traffic control are not included.
- What's the difference between prime coat and tack coat?
- Prime coat is sprayed onto a granular (unpaved) base to bind its surface and help the first asphalt lift bond to it. Tack coat is a much thinner application between two asphalt layers, or onto existing asphalt/concrete, purely for bonding. They use the same area × rate math, just different typical rates and a different substrate.
- Why does the rate have to be entered in gal/yd²?
- US paving specifications (state DOTs, Asphalt Institute MS-19) conventionally state prime/tack rates this way, so that's what a project spec sheet will hand you. The total quantity result still converts correctly between US gallons and litres.
- My spec gives the rate in L/m² — what do I enter?
- Divide by 4.527 to convert L/m² to gal/yd² (e.g. 0.5 L/m² ÷ 4.527 ≈ 0.11 gal/yd²), then enter that.
- How many gallons of tack coat for 1,000 square yards?
- 50 gallons at a residual rate of 0.05 gal/yd², or 52.5 gallons with the default 5% allowance for spray-bar overlap. Entering the same area as 9,000 ft² gives the same result. Use the rate your project specifies.
- Do I enter the paving area in square feet or square yards?
- Either. The area box starts in square feet; choose yd² from its unit list to enter square yards, or use m² in metric. The calculator converts the area to square yards before multiplying by the rate, which is always entered in gal/yd².
Method & typical rates
Asphalt Institute MS-19 'Basic Asphalt Emulsion Manual' and state-DOT standard specifications for prime/tack coat application rates (residual gal/yd² or L/m²), e.g. FHWA-referenced pavement construction guidance.
Unit conversion
1 US gal/yd² ≈ 4.5273 L/m² (exact unit algebra from NIST SP 811 conversion factors).
Tack coat residual rates (FHWA)
FHWA Tech Brief 'Tack Coat Best Practices' (FHWA-HIF-16-017, April 2016), Table 1 — Asphalt Institute recommended residual tack coat rates: new asphalt 0.02–0.05, existing asphalt 0.04–0.07, milled surface 0.04–0.08, Portland cement concrete 0.03–0.05 gal/yd². The brief recommends specifying tack coat rates as residual asphalt.
Tack coat residual rates (FHWA) — reference
About the Bituminous Prime & Tack Coat Calculator
The Bituminous Prime & Tack Coat Calculator turns a paved area and an application rate into the total bituminous material needed, for either a prime coat (applied to a granular base before the first asphalt lift) or a tack coat (a thin bonding layer between two asphalt lifts). Both are the same area-times-rate calculation — this one tool covers both so the site doesn't carry two near-identical pages. Application rate is entered directly in gal/yd² (the unit state DOT and Asphalt Institute MS-19 specifications use), matching how a project's specified rate is normally given; the total quantity output converts properly between US gallons and litres.
What you enter
- Area to treat
- Coat type
- Application rate — Typical residual rates: prime coat 0.25–0.50 gal/yd² (FHWA/Asphalt Institute MS-19); tack coat 0.03–0.10 gal/yd² residual (state-DOT specs — undiluted emulsion applies more before it breaks). Use the rate specified for your project.
- Waste allowance — Default 5%. Adjust to your own allowance — the exact figure is always shown too.
What you get back
- Total bituminous material — Rate entered in gal/yd² (US practice); this total converts properly to litres.
The formula, a worked example, the assumptions behind it and the sources are shown in full below the calculator.
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