To underestimate is to guess that something is worth less or is smaller than it really is. You might underestimate the size of a one-pound hamburger until you realize it's too big to fit in your stomach.

When you "estimate" you take a guess at something, and when you underestimate, your guess falls short or below. If you underestimate how much something costs, you might show up at a store without enough money, and if you underestimate the strength of an opponent who is small, you might find yourself on the ground wondering what hit you. Often when we "assume" something, we make a guess based on how things appear — that's one way to underestimate.

Definitions of underestimate

v make too low an estimate of

“he underestimated the work that went into the renovation”
“Don't underestimate the danger of such a raft trip on this river”
overestimate, overrate
make too high an estimate of
sell short
underestimate the real value or ability of
Type of:
judge incorrectly

v assign too low a value to

“Don't underestimate the value of this heirloom-you may sell it at a good price”
overestimate, overvalue
assign too high a value to
Type of:
fix or determine the value of; assign a value to

v make a deliberately low estimate

Type of:
approximate, estimate, gauge, guess, judge
judge tentatively or form an estimate of (quantities or time)

n an estimation that is too low; an estimate that is less than the true or actual value

underestimation, underrating, underreckoning
Type of:
approximation, estimate, estimation, idea
an approximate calculation of quantity or degree or worth

Sign up, it's free!

Whether you're a student, an educator, or a lifelong learner, Vocabulary.com can put you on the path to systematic vocabulary improvement.