Marathon Time Prediction from a 2-Hour Half Marathon
A 2-hour half marathon predicts a full marathon time of approximately 4 hours and 10–15 minutes using the Riegel formula.
How to use this tool
- Enter known race distance, finish time — minutes and finish time — seconds in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your marathon time and the full breakdown beneath it.
The half marathon is the best predictor of marathon performance — see what a 2-hour half suggests for your full marathon finish time.
Frequently asked questions
- How accurate is the Riegel formula?
- For distances within 2–3x of your reference race it is generally accurate within 5%. Accuracy decreases for very long extrapolations.
- What exponent should I use?
- The standard exponent is 1.06. Some calculators use 1.07 for ultra distances. This tool uses 1.06.