PCR Cycle Calculator

Plan denaturation, annealing, and extension times with confidence. Estimate copies, mass, concentration, and runtime quickly. Review cycle-by-cycle growth for smarter wet-lab setup choices daily.

Calculator Inputs

Example Data Table

Scenario Initial Copies Cycles Efficiency % Decay % Length bp Volume µL Adjusted Copies DNA ng Time
Short clean amplicon 100 35 95.0 0.8 250 25 1.246E+11 34.1495 00:44:45
Medium fragment assay 500 30 90.0 0.5 450 20 4.012E+10 19.7854 00:39:30
Fast screening reaction 1,000 28 85.0 1.2 150 50 3.358E+9 0.5521 00:37:24

Formula Used

1. Constant efficiency model: Copies = Initial Copies × (1 + Efficiency)Cycles.

2. Decay adjusted model: Each cycle uses a reduced efficiency. Effective Efficiency = Base Efficiency × (1 − Decay × Previous Cycles).

3. Cycle factor: Cycle Factor = 1 + Effective Efficiency.

4. Updated copies: New Copies = Previous Copies × Cycle Factor.

5. Suggested extension: Suggested Extension Seconds = Amplicon Length ÷ Polymerase Speed.

6. Estimated DNA mass: DNA ng = Copies × bp × 660 ÷ Avogadro Constant × 109.

7. Estimated concentration: Concentration = DNA ng ÷ Reaction Volume µL.

This calculator gives planning estimates. Real PCR yield depends on template quality, primer design, reagent balance, instrument behavior, and plateau effects.

How to Use This Calculator

  1. Enter the starting template copies for your reaction.
  2. Choose the total number of amplification cycles.
  3. Set expected cycle efficiency and any planned efficiency decay.
  4. Enter amplicon length and reaction volume.
  5. Add denaturation, annealing, extension, and final extension times.
  6. Set ramp overhead if your instrument adds transition delay.
  7. Provide polymerase speed to compare entered extension against a suggested minimum.
  8. Submit the form to view results above the calculator, inspect the graph, and export CSV or PDF files.

PCR Cycle Planning Notes

Why cycle timing matters

PCR performance depends on both chemistry and timing. Very short denaturation or annealing stages can reduce product quality, while long extension stages increase total runtime without always improving yield. A practical cycle calculator helps you balance amplification quality against instrument availability and daily workflow targets.

Why efficiency decay matters

Ideal doubling rarely continues across every cycle. Primer depletion, inhibitor carryover, polymerase fatigue, and product competition gradually reduce performance. That is why this tool reports both constant efficiency growth and decay adjusted growth. The comparison helps you judge how optimistic a simple doubling model might be.

Why mass and concentration help

Copy count alone can feel abstract during laboratory planning. Estimated DNA mass and concentration make the output easier to connect with downstream steps such as gel loading, cleanup, cloning, or sequencing preparation. These values remain theoretical, but they provide a better planning framework than cycle count alone.

FAQs

1. What does this PCR cycle calculator estimate?

It estimates final copy number, fold amplification, run time, DNA mass, concentration, and cycle-by-cycle growth using both constant and decay adjusted efficiency models.

2. Why are two copy estimates shown?

One assumes the same efficiency every cycle. The other reduces efficiency gradually. The second estimate is usually more realistic for longer runs.

3. Does PCR always double product every cycle?

No. Perfect doubling is an ideal assumption. Real reactions lose efficiency because of reagent limits, product competition, suboptimal primers, and template issues.

4. What is efficiency decay per cycle?

It models a small drop in amplification strength from one cycle to the next. It helps you avoid overestimating yield in later cycles.

5. How is suggested extension time calculated?

The calculator divides amplicon length by polymerase speed. This gives a practical minimum extension estimate for your chosen fragment size.

6. Is the DNA mass output exact?

No. It is a theoretical estimate based on molecule count and fragment length. Actual recovered mass depends on chemistry, cleanup, and measurement method.

7. Can I use this for qPCR planning?

It can help with timing and broad amplification expectations, but it does not replace proper qPCR efficiency analysis, baseline handling, or Cq interpretation.

8. Why is total runtime important?

Total runtime affects throughput, instrument scheduling, and thermal exposure. A small timing change per cycle can significantly alter the full run length.

Related Calculators

Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.