# Svetloslav Novoselski: Pace Calculator

> Svetloslav Novoselski is a senior full-stack software engineer based in Sofia, Bulgaria, who builds and ships his own web products, and an amateur road runner who races 5K to 20K. His site, novoselski.net, has two sides: Engineer (products, bio, principles) and Runner (personal bests, race results, upcoming races, free running tools).

Source: https://novoselski.net/runner/pace-calculator  
Last updated: 2026-10-11

A free running pace calculator. No sign-up, no ads. Pace, speed, distance and finish time are linked: change any one and the other three recalculate instantly.

## Features

- Four linked fields: distance, finish time (hh:mm:ss), pace (min per km or mile) and speed (km/h or mph).
- Switch between kilometres and miles at any time.
- One-tap distance presets: 5K, 10K, half marathon (21.0975 km) and marathon (42.195 km).
- Times accept `mm:ss` or `hh:mm:ss`; a bare number is read as minutes.

## Formulas

- Pace (min/km) = finish time ÷ distance (km)
- Speed (km/h) = 60 ÷ pace (min/km)
- Finish time = pace × distance
- 1 mile = 1.609344 km

## Example

A 10K at 5:00 /km finishes in 50:00, which is 12 km/h (8:03 per mile).