THCA vs. THC Percentages: What Lab Results Actually Mean When You Smoke

Mar 28, 2025

THCA vs. THC on Lab Results: What the Numbers Actually Mean

Ever open a COA and see separate lines for THCA and THC? Or a “Total THC” that doesn’t match either number? You’re not alone. This guide breaks down how labs calculate THC from THCA, why the math matters, and how to compare products (flower, carts, disposables) with confidence.

Quick Primer: THCA vs. THC

THCA is the non-intoxicating acid form found in raw flower and many concentrates before heat is applied.
THC (Δ9-THC) is the active compound created when THCA is heated (vaping, dabbing, smoking) — a process called decarboxylation.

Because flower and live resin typically start out rich in THCA, labs show both values. Retail labels often highlight “Total THC,” which is the amount of THC you should expect after THCA converts during use.

The Formula Labs Use (and Why 0.877 Matters)

When THCA converts to THC, it loses a small piece of its molecular mass (CO₂). Labs account for that with a factor of 0.877:

Total THC = (Δ9-THC) + (THCA × 0.877)

Example (flower):
If a strain shows Δ9-THC = 1.2% and THCA = 28.0%, then:
Total THC ≈ 1.2 + (28.0 × 0.877) = 1.2 + 24.56 = 25.76%

Why it won’t match your high exactly: real-world variables — temperature, device voltage, moisture, terpene content — all affect how completely THCA converts and how the effects feel.

“Total THC” vs. “Total Cannabinoids”

Total THC is specific to Δ9-THC + converted THCA via the 0.877 factor.
Total Cannabinoids includes THC + minor cannabinoids (CBG, CBC, CBN, etc.). A higher total cannabinoids number does not mean higher THC.

If you’re comparing potency, look at the Total THC line. If you’re shopping for the full experience (flavor, nuance, and “vibe”), also factor in the terpene panel and the presence of minor cannabinoids.

Flower vs. Vapes: How Lab Numbers Translate

THCA Flower

Most high-quality hemp flower is reported as high THCA, low Δ9-THC, then converted to THC when smoked or vaped. Moisture, cure, and terpenes influence how that potency feels. Explore our current strains here:

Shop THCA Flower Collection
Super Silver Haze 26.654% THCA — classic, bright profile
Grease Monkey 35.431% THCA — gas & depth

Live Resin / Live Rosin Disposables

Cartridges and disposables often show higher Δ9-THC on the COA because the oil is ready-to-vape. If the label lists THCA, the same 0.877 conversion applies to estimate Total THC. For the best plant-like flavor and effects, check that the product is live resin or live rosin and look for a published terpene panel.

How to Compare Two Products Using the COA

Find Δ9-THC and THCA. Calculate Total THC with THCA × 0.877 + Δ9-THC.
Check terpene total and top terpenes. 2–4% total terpenes is typically very aromatic. Limonene/terpinolene (bright), caryophyllene/linalool (dessert), myrcene/humulene (gas/earth), pinene (pine/focus).
Scan minor cannabinoids. Even 0.5–2% CBG/CBC can change how the product feels.
Consider form factor. Fresh, well-cured flower in mylar and live concentrates will preserve more native compounds.

Pro move: If two items have similar Total THC, pick the one with the richer terpene panel and meaningful minors. That’s usually the tastier, more satisfying choice.

Common Pitfalls & How to Avoid Them

Only chasing %: High numbers can come from dry flower or narrow-spectrum oil. Don’t ignore terpenes.
No terp panel on the COA: Harder to predict flavor/effects. Favor products publishing full results.
Inflated “total cannabinoids” marketing: Confirm the actual Total THC line used for comparisons.
Overheating devices: High temps burn through oil and terpenes faster. Start low and step up.

FAQs

Q: Why does the store label sometimes show a single “Total THC” number?
A: It’s the simplified, consumer-facing value using the 0.877 conversion. The full breakdown lives on the COA.

Q: My flower says 30% THCA — should it feel stronger than 24%?
A: Not necessarily. Moisture, cure, terpenes, and minor cannabinoids affect perceived potency. Many shoppers prefer terp-rich 24–28% over drier, higher-testing jars.

Q: Do disposables list THCA or THC?
A: Depends on the oil. Some live oils report Δ9-THC directly; others include THCA. Use the formula to compare apples-to-apples.

Shop by Numbers — and by Spectrum

Use Total THC for potency, but don’t stop there. The terpene panel and minor cannabinoids tell you how the product will actually taste and feel.

Brenton Bird