t₀ is the time at which measurement started. Fill in the progress at that time into p₀. When more progress has been made, fill out the second column, t₁. The tool will linearly extrapolate to find t_end.

	t0		t1		tend
Time:
	now		now
Progress:
	p0		p1		pend

Result

start =		= t0
elapsed =		= t1 - t0
remaining =		= tend - t1
total =		= (t1 - t0) / (p1 - p0) × (pend - p0)
finish =		= t0 + total

Visually truncate to decimal(s). Colon notation always truncates.

Usage notes

• Inputs are evaluated as JavaScript to support entering e.g. 23*3600. Only [0-9 :./*+-] is allowed to prevent self-xss.
• A start time in the past works fine if you know what the progress was back then. You can enter it as negative value, or use the wall clock time from 2 hours ago.

Colon notation

• For convenience, the first colon is replaced with +1/60* and the second with +1/3600*, such that hh:mm and hh:mm:ss will parse. The output unit will be that of the largest position (hours in the case of hh:mm or hh:mm:ss, minutes in the case of mm:ss).
• Entering 0:5 is the same as 0:05 or 1/60*5.
• Days are not supported: it keeps using powers of 60 when you enter xx:hh:mm:ss.