Agree..if 0 point, 0 cost, it sure worth to do refi. Number tal

(provided one would like to pay the same payment amount as if they didn't do refi..)
suppose 200k loan, 5.5%, 30 year: $1,135.58/mon
$200,000.00
1 $13,626.96 $2,694.20 $10,932.76 $197,305.80
2 $13,626.96 $2,846.17 $10,780.79 $194,459.63
3 $13,626.96 $3,006.73 $10,620.23 $191,452.90
4 $13,626.96 $3,176.32 $10,450.64 $188,276.58
5 $13,626.96 $3,355.49 $10,271.47 $184,921.09
6 $13,626.96 $3,544.78 $10,082.18 $181,376.31
7 $13,626.96 $3,744.74 $9,882.22 $177,631.57
8 $13,626.96 $3,955.98 $9,670.98 $173,675.59
9 $13,626.96 $4,179.11 $9,447.85 $169,496.48
10 $13,626.96 $4,414.86 $9,212.10 $165,081.62
11 $13,626.96 $4,663.89 $8,963.07 $160,417.73
12 $13,626.96 $4,926.94 $8,700.02 $155,490.79
13 $13,626.96 $5,204.86 $8,422.10 $150,285.93
14 $13,626.96 $5,498.47 $8,128.49 $144,787.46
15 $13,626.96 $5,808.62 $7,818.34 $138,978.84
16 $13,626.96 $6,136.26 $7,490.70 $132,842.58
17 $13,626.96 $6,482.40 $7,144.56 $126,360.18
18 $13,626.96 $6,848.07 $6,778.89 $119,512.11
19 $13,626.96 $7,234.37 $6,392.59 $112,277.74
20 $13,626.96 $7,642.43 $5,984.53 $104,635.31
21 $13,626.96 $8,073.51 $5,553.45 $96,561.80
22 $13,626.96 $8,528.94 $5,098.02 $88,032.86
23 $13,626.96 $9,010.02 $4,616.94 $79,022.84
24 $13,626.96 $9,518.28 $4,108.68 $69,504.56
25 $13,626.96 $10,055.16 $3,571.80 $59,449.40
26 $13,626.96 $10,622.37 $3,004.59 $48,827.03
27 $13,626.96 $11,221.55 $2,405.41 $37,605.48
28 $13,626.96 $11,854.53 $1,772.43 $25,750.95
29 $13,626.96 $12,523.22 $1,103.74 $13,227.73
30 $13,625.06 $13,227.73 $397.33 $0.00

if 5.375%, monthly payment is: $1,119.94; if in stead, you still pay $1,135.58/mon(15.64 more than required).

$200,000.00 $200,000.00
1 $13,439.28 $10,682.75 $197,243.47 $13,626.96 $10,678.06 $197,051.10
2 $13,439.28 $10,530.87 $194,335.06 $13,626.96 $10,515.58 $193,939.72
3 $13,439.28 $10,370.65 $191,266.43 $13,626.96 $10,344.16 $190,656.92
4 $13,439.28 $10,201.58 $188,028.73 $13,626.96 $10,163.29 $187,193.25
5 $13,439.28 $10,023.20 $184,612.65 $13,626.96 $9,972.48 $183,538.77
6 $13,439.28 $9,835.01 $181,008.38 $13,626.96 $9,771.14 $179,682.95
7 $13,439.28 $9,636.42 $177,205.52 $13,626.96 $9,558.71 $175,614.70
8 $13,439.28 $9,426.90 $173,193.14 $13,626.96 $9,334.55 $171,322.29
9 $13,439.28 $9,205.84 $168,959.70 $13,626.96 $9,098.08 $166,793.41
10 $13,439.28 $8,972.61 $164,493.03 $13,626.96 $8,848.58 $162,015.03
11 $13,439.28 $8,726.54 $159,780.29 $13,626.96 $8,585.31 $156,973.38
12 $13,439.28 $8,466.89 $154,807.90 $13,626.96 $8,307.55 $151,653.97
13 $13,439.28 $8,192.93 $149,561.55 $13,626.96 $8,014.46 $146,041.47
14 $13,439.28 $7,903.88 $144,026.15 $13,626.96 $7,705.24 $140,119.75
15 $13,439.28 $7,598.92 $138,185.79 $13,626.96 $7,378.99 $133,871.78
16 $13,439.28 $7,277.16 $132,023.67 $13,626.96 $7,034.78 $127,279.60
17 $13,439.28 $6,937.66 $125,522.05 $13,626.96 $6,671.59 $120,324.23
18 $13,439.28 $6,579.44 $118,662.21 $13,626.96 $6,288.39 $112,985.66
19 $13,439.28 $6,201.52 $111,424.45 $13,626.96 $5,884.08 $105,242.78
20 $13,439.28 $5,802.76 $103,787.93 $13,626.96 $5,457.47 $97,073.29
21 $13,439.28 $5,382.03 $95,730.68 $13,626.96 $5,007.42 $88,453.75
22 $13,439.28 $4,938.13 $87,229.53 $13,626.96 $4,532.51 $79,359.30
23 $13,439.28 $4,469.77 $78,260.02 $13,626.96 $4,031.45 $69,763.79
24 $13,439.28 $3,975.57 $68,796.31 $13,626.96 $3,502.79 $59,639.62
25 $13,439.28 $3,454.19 $58,811.22 $13,626.96 $2,945.02 $48,957.68
26 $13,439.28 $2,904.10 $48,276.04 $13,626.96 $2,356.51 $37,687.23
27 $13,439.28 $2,323.67 $37,160.43 $13,626.96 $1,735.58 $25,795.85
28 $13,439.28 $1,711.25 $25,432.40 $13,626.96 $1,080.43 $13,249.32
29 $13,439.28 $1,065.11 $13,058.23 $13,626.96 $389.20 $11.56
30 $13,441.58 $383.35 $0.00 $11.61 $0.05 $0.00

save you almost 1 year's payment, which is:
1,135.58*12-383.35=13243.61.. this is saving againest your old payment(if don't do refi)