Original instructional diagram for Primer Tm and Annealing Temperature: Keep the Assay Conditions Together. Values, when shown, are illustrative; clinical images do not recommend a dose.
Keep Tm inputs on one basis
Two Tm values calculated under different salt or concentration assumptions are not automatically comparable. The lower of two entered primer values is only as meaningful as those inputs. Record how each was obtained before combining it with a product Tm.
Use Annealing Temperature Calculator to work through these inputs while keeping the displayed assumptions in view.
Do not turn an estimate into a protocol
A numerical temperature estimate does not establish specificity, yield or compatibility with a polymerase. An assay needs its own validated method. A plausible-looking result can still be unsuitable when the input Tm model does not match the reaction conditions.
This question belongs to the Bio laboratory calculators group within Biology calculators.
Read the calculation on its stated basis
Ta ≈ 0.3 × lower primer Tm + 0.7 × product Tm − 14.9 °C.
This is an empirical input-Tm estimate, not a sequence-design or thermocycler protocol generator.
Retain the input definitions and units with the result. A later comparison should use the same basis; a change in method is a new scenario, not simply a more precise version of the old number.
Keep related questions separate
qPCR Efficiency Calculator addresses a related part of the measurement or interpretation task. Check its own method before carrying a value from one tool to the other.
For a related perspective, read qPCR Standard-Curve Slopes: Check the Log Base and Apparent Efficiency.
For tools in other subjects, return to GreenCalc. Keep the calculator result with its assumptions rather than using a link or a matching unit as evidence that two models are interchangeable.
By GreenCalc · Updated 2026-11-05