PCR Elongation Time Calculator

Dial in extension time for any amplicon, enzyme, and temperature quickly accurately. See per-cycle and total run time, then download a protocol sheet ready.

Calculator

Typical range: 70–20,000 bp; longer products may need optimization.
Choose a preset or switch to custom rate.
Total elongation time is per-cycle time × cycles.
Custom rate inputs are ignored when a preset is chosen.
Example: 60 sec/kb or 1 kb/min or 16.7 bp/s.
Adds extra time for difficult templates or inhibitors.
Most enzymes run near 68–72°C, depending on chemistry.
Reference used for the optional temperature model.
Round up for clean, repeatable protocol timing.

Advanced temperature adjustment (optional)

Uses a simplified Q10 rule to scale polymerase speed with temperature changes.
Typical heuristic: 1.3–2.0 (clamped internally).
Model: rate(T) = rate(ref) × Q10^((T−Tref)/10). Time scales inversely with rate. This is a rough physical approximation, not a replacement for enzyme datasheets.
Reset

Example data table

Amplicon (bp) Rate (sec/kb) Temp (°C) Margin (%) Rounding (sec) Recommended per cycle
500 30 72 10 5 0:20
1500 60 72 15 10 1:50
8000 90 68 20 30 12:00
Examples are illustrative; confirm with the enzyme manufacturer’s guidance.

Formula used

Base time (seconds) = amplicon_length(bp) ÷ polymerase_speed(bp/s)
rate(T) = rate(ref) × Q10^((T − Tref)/10)
If enabled, time adjusts inversely with the temperature-scaled rate.
Adjusted time = base_time ÷ temperature_factor
With margin = adjusted_time × (1 + margin%/100)
Recommended time = round up to chosen step size

How to use this calculator

  1. Enter your amplicon length in base pairs.
  2. Select a polymerase preset, or choose custom and enter your rate.
  3. Set extension temperature and cycles to match your program.
  4. Add a safety margin for difficult templates or inhibitors.
  5. Pick a rounding step to keep timings practical.
  6. Optionally enable Q10 if you changed temperature from the reference.
  7. Press Calculate, then download CSV or PDF for your notebook.

Accurate elongation timing helps deliver clean amplification results consistently.

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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.

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